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Oldsmobile

Gen 2 V-8 Engines from 1964 through 1987 Including the 260-403 Small Block and 400-455 Big Block

Developed Exclusively for: The Automotive History Preservation Society Copyright 2015

Use Without Permission Violates Copyright

Forward I published the original of this manual back in the late 1970’s when Oldsmobiles and muscle cars in general had been relegated either to junkyards or sat dusty and unused in garages – mostly because of two colossal gas price increases, a huge jump in insurance pricing, and Uncle Sam’s new emission control regulations. As you probably know, by the time 1978 arrived, the American auto manufacturers had basically totally exited the performance marketplace. In a single decade it was as if the knowledge of muscle cars and ways to increase the performance of the American V8 just disappeared – as if a comet had struck the Earth and killed off all that knowledge. That phenomenon still strikes me as weird to this day. As a gearhead who grew up in and around the horsepower crazed 60s and birth of American muscle car, I was amazed by the almost total loss of information about hopping up Oldsmobile 442s and Cutlasses. My friends and I would sit around and lament the fact that except for a few of us, everyone seemed to be a dunce when it came to extracting some performance from an Olds V8. Then it struck me; it was I who was the dunce. I realized that: 1) there was a whole new generation of people who had been kids when these cars roamed the streets, 2) Olds had been kind of stingy in handing out performance information, and 3) there just had never been any real Olds performance publications out there. So one day I sat down and compiled all the information I knew about Oldsmobile performance parts and the factory muscle cars, and the original Olds Performance Manual was born. Since then, I moved on to other things and the Manual ran out of print. But recently I have realized that the cars have been resurrected and are found everywhere, but once again all that lore has been lost. So our friends sat down and determined that the only way to recapture this information was to develop a website dedicated to the preservation and dissemination of things automobile. The offshoot of such is these Manuals – and this one is one of the keystones. So here is Oldsmobile Performance - Part Three. Inside you will find many of the part numbers that can no longer be found in GM’s parts catalog and even on websites and forums. Many of the parts are still out there - either as NOS or NROS – so hopefully these listings will help. So grab this Manual and go for it! Bob Gerometta

Palm Harbor, Florida March 2007

PS. Thanks to Dana Page and Helen Early of Oldsmobile Public Relations, who annoyed me until I did the first edition - and then supported me with tons of materials and pictures; my gearhead friends in Smithtown New York who helped print that first run; and Paul Tortorici, of Hackensack New Jersey who reinvigorated my desire to update the book back in the mid 1980’s. And thanks to my wife Sue, who puts up with the tons of information I collect on performance cars and such and enjoys our current rides almost as much as I do.

The picture that graced the front cover of the original manual – circa 1977

- i -

Introduction General This document is not intended to be the Ten Commandments of Oldsmobile engine modification – no document or manual could do that or be so perfect. It was and is intended to be a guide to those people wishing to get better performance out of their 1964 trough 1989 Oldsmobile - powered by an Oldsmobile Division V8 produced in that period. We've updated the original Olds Performance Manual with tips on the 403 and 307 Oldsmobile Division V8s, as well as information on improving the performance of the last body on frame car (G Body) that was produced from 1978 to 1987. Each suggestion will improve performance, but it will not turn a worn out, 200,000 mile oil burner into a ten second quarter miler. Many will ask; “Why did you recommend this product over that one?”, or “How come you did not say anything about Zilch cams? They worked for me”. The answer is that the products we’ve recommended in this Manual were designed by people who had tons of experience in getting the most out of an Olds. And based on our own experience – these are the products that worked great for us and many other successful modifiers and racers. Some parts are no longer available across the counter, especially the factory pieces, but where we recommend them, they may still be the best for your vehicle. So we suggest that you scrounge the Internet and swap meets for them. Another piece of advice: if you are unsure, use a factory performance part. Back in the day, the factory didn’t have race teams and performance companies using CAD and computer simulations to build replacement parts, but they did do extensive testing of what they did release and they took a lot of feedback from racers and the average Joe (something that seems to be a lost art). Take if from us – the old stuff works- especially on the cars that will see a lot of street time and an occasional sortie to the strip or road course! Last, this manual makes no guarantee for any product. The manufacturer alone bears any responsibility for their products, not Wild About Cars, LLC, the authors, or anyone else mentioned herein. Check the guarantee and/or warrantee of any product before you purchase it – for your own protection.

On Information Available There is more information out there on rebuilding and modifying Olds engines than could ever be placed in one document. Thus, this document focuses on stuff that we know works. If you want controversy, sign on to all the Olds (both at Wild About Cars and wherever) forums and go for it. You will get a lot of information, some BS, and lots of opinions – with no way to sort it out. Trying to find reasonable information from multiple sources manner is like asking; “What was the best college basketball team ever?” As part of the development of Wild about Cars, we spend lots of time web surfing and believe me, we see more misinformation and opinion than facts. Please be careful with all that material – it’s not only your money but your safety as well. What we have tried to do here is use our collective experience to sort through all that stuff and come up with a logical and practical approach. Everything in this manual will work well and reliably and make your Olds motor sing. That’s what this document is all about. You can read this and use it as a reference guide, or decide that it is toilet paper - it's your choice. So if after reading it, you have a different opinion on what works best remember, there is still valuable information in here. With that said, we are always interested in ideas and information. So you may offer a suggestion on a revision to the manual (after all it’s virtual), by sending your comments to [email protected]. But if you do, please give us some facts to back your idea up. If it seems appropriate or reasonable, we'll include it in our updates and credit you.

This Book Covers Engine Modification Only This Manual covers engine modification only. For Chassis and other information such as running gear and peripherals, see Oldsmobile Chassis and Running Gear Modification. The materials became too voluminous to include in one book. Further, updates, changes and alterations regarding engines are likely to occur more frequently, making revised editions a nightmare. We hope you will bear with us and see the value in the two volume approach. We hope that by following this rout, we can keep costs down and not confuse the user.

- ii - Table of Contents

This book contains engine modification information for the Oldsmobile Division of General Motors Corporation V-8 engines from 1964 through 1989. Earlier engines and the V-6 are covered in separate manuals. Forward ...... i Introduction ...... ii General ...... ii On Information Available ...... ii This Book Covers Engine Modification Only ...... ii Section 01 - Preparation and Planning ...... 1 1.0 Thinking about your Approach...... 1 Introduction ...... 1 Modification Levels ...... 1 What Block to Start With...... 1 Begin at the Beginning ...... 2 First – Short Block Basics ...... 3 Second – The Heads and Basics ...... 3 Third - Induction System Basics ...... 4 A Note on Part Numbers ...... 4 A Note on NROS Parts ...... 4 A Note on Engine Builders ...... 5 1.1 Comparative Size, Dimensions & Specifications – Block versus Block ...... 5 1.2 Engine Identification ...... 6 Identifying Engines – Small Block V-8 Engines ...... 6 The Small Block Engine - Identification at a Glance ...... 6 Identifying Engines – Big Block V-8 Engines ...... 7 The Big Block Engine - Identification at a Glance ...... 7 1.3 Key Specifications 1961-1978 V-8 Engines ...... 8 Factory Specifications - Engine ...... 8 Section 02 - Block Basics ...... 11 2.0 Small Block ...... 11 Generation 1 Cast Iron Small Block V-8 Facts ...... 11 Generation 2 Cast Iron Small Block V-8 Facts ...... 12 Generation 2 Cast Iron Diesel 260 and 350 Block Facts ...... 12 Small Block Key Differences ...... 12 2.1 Big Block ...... 14 Generation 2 Big Block Facts ...... 14 Generation 2 Big Block Key Differences ...... 15 2.2 Identification ...... 18 Crankshaft Identification – Forged Cranks ...... 18 Flexplate ...... 18 Crankshaft Identification – Cast Cranks ...... 19 Flexplate ...... 19 2.3 Factory Specifications V-8 Engines ...... 20 Factory Specifications – Block Info ...... 20 Factory Specifications – Head Info ...... 21 Factory Specifications – Head Info Continued ...... 22 Factory Specifications – NOS and Valve Springs ...... 23 Factory Specifications – NOS Camshafts and Valve Springs Continued ...... 24 Factory Specifications - NROS Camshafts and Valve Springs ...... 25 Factory Specifications - NROS Camshafts and Valve Springs Continued ...... 26 Section 03 – Building Your Short Block ...... 27 3.0 Some Decisions ...... 27 The First Decision – What Block to Start With ...... 27 Decision Number Two - What Body is Best for a Particular Size Block ...... 27 Decision Three – How Much to Spend on Modification ...... 28 Decision Four - Primary Use Considerations ...... 29 Decision Five – The Major Components to Use ...... 29 3.1 Camshaft Selection ...... 30 Considerations ...... 30 Suggested Cams ...... 31 Cam and Thoughts ...... 31 Cam and Intake Manifold Thoughts ...... 31 Cams and Vehicle Weight ...... 31 Cam Selection Using the Chart ...... 31

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Additional Cam Information ...... 32 Lifter Recommendations ...... 32 Lifter Preload ...... 32 Valve Spring Selection ...... 32 A Note on Valve Span and Potential Valve Shrouding ...... 32 Valve Span and Potential Shrouding – Standard Valve Span ...... 34 Valve Span and Potential Shrouding – Maximum Valve Span ...... 35 Recommended Valve Sizes ...... 35 Recommended Aftermarket Camshafts – by Application ...... 36 Recommended Aftermarket Camshafts – by Application Continued ...... 37 3.2 The Build – General Rules ...... 38 Basic Machining and Blueprinting Issues ...... 38 Other Assembly and Machining Issues ...... 39 3.3 Increasing Displacement ...... 40 Introduction – What Works ...... 40 Increasing Displacement on the 350 Diesel ...... 40 Increasing Displacement on the 455 ...... 41 3.4 Suggested Builds – By Block ...... 41 Introduction ...... 41 Suggested 260 and 307 Engine Mods...... 42 Suggested 330 and 350 Engine Mods...... 43 Suggested 403 Mods ...... 44 Suggested 400 SS and 425 Mods ...... 45 Suggested 400 LS and 455 Mods ...... 47 Assembly and Peripherals ...... 50 3.5 Block Machining and Preparation ...... 50 Block Preparation – General ...... 50 Maximum – by Block ...... 51 Specific Block Machining ...... 51 Engine Boring – Net Result ...... 54 3.6 Crankshaft, and Preparation ...... 55 Crankshaft Preparation and Modification - All ...... 55 Crankshaft Preparation and Modification – Cast Units ...... 55 Main Bearing Modification to Ensure Proper Oiling ...... 56 Manual ...... 56 Connecting Rod Preparation - General ...... 56 Rod Bolt Reuse ...... 57 Rod Clearance ...... 57 Connecting Rod Prep – Olds Oiling Issues ...... 57 Aftermarket Rods ...... 58 Piston Preparation ...... 58 Strengthening the Block Assembly ...... 58 Engine Harmonic Balancer ...... 59 Completing the Short Block ...... 59 3.7 Special Section – Stroking the 350 Diesel and 455 ...... 60 Introduction ...... 60 Stroking the 350 Diesel ...... 60 Stroking the 455 ...... 61 3.8 Engine Oiling ...... 61 Introduction ...... 61 Oil Pump and Oiling System Described ...... 61 Oil Pump Selection ...... 62 Oil Pump Drive ...... 62 Oil Pan Capacity and Pickup ...... 63 Oil Pan Selection ...... 63 Crank Scrapers and Full Length Windage Trays ...... 64 Mounting the Oil Pump ...... 64 Oil, Oil Filter and Oil Pressure ...... 64 3.9 Assembling Your Short Block ...... 65 Installing the Crankshaft, and Connecting Rods ...... 65 Installing the Cam ...... 65 Checking Camshaft Retaining Bolt and Thrust Clearance ...... 65 Install the lifters ...... 65 Install the Cam Timing Chain and Gears ...... 65

- iv - Table of Contents

The Right Timing Chain and Gears ...... 66 A Note on Degreeing the Cam ...... 66 A Note on Camshaft Break-In ...... 66 Installing a Harmonic Balancer ...... 66 Scribing a New Timing Mark on the 350-455 Harmonic Balancer for the 330 V8 ...... 67 Section 04 - Building Your Cylinder Heads ...... 68 4.0 Picking the Correct Head ...... 68 Introduction ...... 68 The Right Head for You ...... 68 Unleaded and Cylinder Head Preparation and Use ...... 68 4.1 Head Selection Criteria and Other Potential Tweaks ...... 69 Introduction ...... 69 Head Considerations for "Stock" Vehicles ...... 69 Head Considerations for Factory Modified Vehicles ...... 69 Head Considerations for Street Mild Vehicles ...... 70 Head Considerations for Street Wild Vehicles ...... 70 Head Considerations for Street/Strip Vehicles ...... 70 Head Considerations for Super Modified Vehicles ...... 70 Recommended Valve Sizes ...... 71 4.2 Building Your Heads ...... 71 Head Inspection and Preparation ...... 71 Head Milling - General ...... 71 Head Milling - Detail ...... 72 Calculating ...... 72 Head Porting ...... 73 Evening the Mating Surface on the Center Exhaust Ports ...... 73 Sealing Off the Heat Riser Passages ...... 73 Valve Seating and Combustion Chamber Prep ...... 74 Valve Seat Angles ...... 75 Valve Guides ...... 75 Valve Springs ...... 75 The Relationship of Valve Length, Spring Height, Rocker Stand Height and Pushrod Length ...... 76 4.3 Checking Head Tolerances ...... 76 Steps to Ensure that Incorrect Valve Stem Height Does Not Occur ...... 76 Preventing Coil Bind and Other Interference ...... 78 Note on Coil Bind and Spring Height with Pre-1970 Heads ...... 78 Mechanical Lifter Valve Clearance or “Lash” ...... 78 Setting Mechanical Lifter Valve Clearance or “Lash” ...... 78 Hydraulic Lifters and “Preload” ...... 78 How to Set Preload on Stock Olds Valve Train ...... 79 How to Set Hydraulic Lifter Preload ...... 79 4.4 Assembly and Adding Performance Components ...... 80 Valves ...... 80 Rocker Arms ...... 80 Pushrods ...... 81 4.4 Aftermarket Heads ...... 81 Introduction ...... 81 Available Aftermarket Heads ...... 81 Stacking Up – Head vs. Head ...... 83 4.5 Head Comparison Chart – Flow Figures ...... 83 Section 05 - Fuel Delivery, Induction and Exhaust ...... 84 5.0 Key Issues in Fuel Delivery and Induction ...... 84 General Points ...... 84 Intake Manifolds ...... 84 Air Cleaners ...... 85 Ram Air Tips ...... 86 - General ...... 87 General Application & Usage ...... 87 Fuel Delivery ...... 88 Exhaust Headers ...... 89 ...... 90 5.1 Tuning Your Carb for Best Performance – Rochester 4GC ...... 91 Rochester 4GC Carburetors – Information and General Operation ...... 91 Rochester 4GC Carburetors – Performance Tuning ...... 91

- v - Table of Contents

5.2 Tuning Your Carb for Best Performance – Rochester 4MC & 4MV (Quadrajet) Carburetors ...... 93 Rochester 4MC and 4MV (Quadrajet) Carburetors – General Operation and Information ...... 93 Rochester 4MC and MV Carburetors – Performance Tuning and Blueprinting ...... 95 5.3 Carter ThermoQuad Carburetor ...... 100 Carter ThermoQuad Carburetors – General Operation and Information ...... 100 5.4 Carter AFB and AVS Carburetor ...... 102 Carter AFB Carburetor ...... 102 Carter AVS Carburetor ...... 103 5.5 Other Carburetor References ...... 104 Rochester Reference ...... 104 Carter Reference ...... 104 Holley Reference ...... 104 5.6 Carburetor Metering ...... 104 Rochester 4G and 2G main Metering ...... 104 5.6 Carburetor Metering ...... 105 Rochester 4M (Quadrajet) Main Metering ...... 105 Rochester 4M (Quadrajet) Secondary Metering Rod Hangers ...... 105 Rochester 4M (Quadrajet) Secondary Metering Rods ...... 106 Section 06 - Timing and Ignition Systems ...... 107 6.0 Timing ...... 107 Introduction ...... 107 Marking Your Harmonic Balancer ...... 107 Balancers with Pre-set Timing Marks ...... 107 Original Ignition Settings and Considerations ...... 107 Practical Ignition Advance for Unleaded Street Gasoline ...... 108 6.1 Upgrades ...... 109 Modifying Your ...... 109 Upgrading Your Ignition System with New Equipment ...... 109 6.2 Science and Spark Plug Wires ...... 110 Spark Plugs and Plug Heat Range ...... 110 Section 07 - Vendor and Other Listings ...... 111 7.0 Listing Central ...... 111 About These Listings ...... 111 7.1 Vendor Listings ...... 111 7.2 Photo Credits ...... 114 Section 08 - Assembly Worksheets & Other Key Specifications ...... 116 8.0 Specifications ...... 116 8.1 Assembly Worksheet – All Blocks ...... 117 How to Use These Sheets ...... 117 Section 09 - Appendix ...... 124 9.0 Standard Piston Information ...... 124 9.1 Engine Bore and Stroke Compression Changes ...... 124 9.2 Degreeing Your Camshaft ...... 125 Degreeing Procedures ...... 125 Calculating Actual Valve Lift ...... 125 Calculating Cam Duration ...... 125 9.3 Outside Air Induction Scoop Fitment ...... 126 Introduction ...... 126 1966 OAI Scoop Fitment ...... 126 1967 OAI Scoop Fitment ...... 127 1968-1969 OAI Scoop Fitments ...... 128 1970-1972 OAI Hood/Air Cleaner Fitment ...... 129 9.4 Carburetor Part Numbers ...... 130

- vi - Introduction – Preparation and Planning – Section 1

Section 01 - Preparation and Planning

1.0 Thinking about your Approach from Stock to Super Modified (with compression ratio as the only issue). Thus, you can move up through the Introduction performance levels without pulling your engine or dropping pieces in the road. Our theory is that most of you will want to Much of the Engine Section of the Manual is divided by enhance the performance of your Olds over time, and if you block size. Where appropriate, we have combined the have a good foundation, you won’t have to go back to information together. As you know, the 260/307/330/350/403 square one. The idea is that you can build up from Stock to cubic inch version is the “small block” and the 400/425/455 Street/Strip without changing out the short block2. A Super “is the big block”. Both block types are similar and can Modified engine should be built from scratch, but if you did share many components, but the short blocks (block crank, want to go there, your properly prepared block could be rods and pistons) are different. This will be made clear in used. the descriptions in Section 1.2. The original Olds Performance Manual broke the engine What Block to Start With modifications portion into five levels of performance, and while it might seem a bit hokey by today’s standards, we will This is discussed in detail in Section 3, but the premise in keep these designations for clarity. Suffice it to say; only the this Manual is that you are starting your build from the first two levels have any chance of passing today’s sniff ground up, and not just making some tweaks to your existing tests. If you live in states where you car has to pass engine, though you can use the information to do so. But emission control testing, be very careful when modifying you when building a high performance engine, you will obviously engine. get the best performance per cubic inch when you modify an engine that can respond best to the increased loads, rpm and other aspects that produce horsepower. Modification Levels And it’s all about “bang for the buck” when modifying an We will use six levels of performance improvement in this engine. While many of these suggestions will work on any Manual: Olds engine, some blocks are better than others when it . Stock. Back in the day, stock was a pretty loose term, so comes to strength and reliability, and others are limited by we include it and tell you what you can get away with if the size they can be brought out to or are limited in you are looking to tweak your rare, restored Olds without availability of high performance parts. running afoul of car show judges. For example, the small block cannot support more than 380 . Factory High Performance. Factory High Performance is cubic inches and still have a bullet proof lower end. The 403 bringing you engine up to the best specifications that is an iffy choice for a true high performance engine because 3 your engine block would have experienced in 1969 – of its "windowed" main webs . And the long stroke 400, the 1971 - as if it had been equipped as a “W” Code car. 260, and 307 have bore sizes which shroud the intake valve. These cars were optimized for horsepower and with drag 1 These engines can all make horsepower, but, at some point, racing in mind . they will become a liability if further modification is sought, or . Street Mild. Street Mild takes what the Factory learned they will be unable to make the horsepower you may need. and then tweaks it with some aftermarket and tuning So if you are seeking a certain level of power or you have a tricks the boys in Lansing weren’t allowed to do. certain performance level in mind, don't limit yourself or reach a development dead end by starting with the wrong . Street Wild. A Street Wild car will not likely pass any block. state’s sniff test, and unless your spouse or significant other is a gear head, they will not like riding around in Consider: your Olds – but you definitely will.  Getting more than 200 HP from the 260 requires as . Street/Strip. A Street/Strip car is a drag or road race car much expense as getting 350 HP from a 330/350. that you will barely be able to drive to the event, but  A 307 will not stay intact if you want to consistently rev it when you get there – hang on! past 5500 rpm, whereas a 330/350 will handle 1000 rpm past that all day long. . Super Modified. Get a trailer.  A 403 is a good street (moderate rpm) engine, but not a Our theory in Section 3, Engine Block, is to build a bullet race engine. It will fail in high rpm trim. Though the proof block that can be used in any level of performance –

1 Since most of you will not have any or only rudimentary computer 2 controls on your 1964 – 1989 Olds, we can take advantage of what This doesn’t mean that you may not have to replace other worked in the 1960s and early ‘70s and before the computer was components such as cam, heads etc. if you do move up in levels used as an engine tuning tool. However adding modern port fuel of performance. However, you initial investment will not need to be injection and computer controls are discussed in Section 5 of this undone. Manual. 3 See Section 2, Small Block Facts for more information.

- 1 - Introduction – Preparation and Planning – Section 1

valve train will sustain 7500, the lower end will that Oldsmobile chassis are not lightweights (unless consistently fail at anything over 5500. you are stuffing something in an X or H body). Street  A long stroke 400 will never make the same HP as a cars like torque, race cars like BOTH. short stroke 400 and live.  HORSEPOWER: All blocks can be made to make  A 425 can take more rpms than a 455, but the 455 will copious HP. The questions are: 1) how much is it always out torque it. going to cost per dollar; and 2) where in the RPM band do you want the HP. If two engines both So pick what your HP intentions are, what chassis the develop a max HP of 400, but one does it @ 5000 engine will sit in (see below for suggestions), and what your RPM and the other @ 7000 RPM, the one at lower budget is, and then start work. If you have a 260 in your RPM will obviously be easier to drive and use. Cutlass and want more than spirited performance, remove it and install a 330 – 403. If you are going racing, use a  FLAT HP and TORQUE CURVES: Engines that 330/350 or a big block. If you have a 1978 Delta 88 with a have a fairly sharp rise in HP which stays at that 403 and want a good cruiser, the 403 is a great engine to level over a long period will – on the street – be use, but if you are looking for 400 hp, you can get there, but generally quicker than one with higher HP, but eventually you will break the motor. If you are running a delivered in a short RPM band. The same is true for 1968 442, and want it to surprise GTOs, we have a solution engines with a flat torque curve. Peaky engines for you, but if you are going bracket racing, get a 425/455. look great on the dyno, but need tons of gear and Get the idea? eat gas, which at close to $4.00 a gallon, is not fun anymore. Last, remember that the chassis and driveline will likely have to be modified if you add a 50% or more increase in HP and  COST: Generally, an engine with more cubes that torque. Clutches, auto transmissions, rear ends etc were turns lower RPM will cost less to build and maintain usually designed to handle only a certain level of power. than a smaller engine that needs to rev to make HP. This is less true in the 60s and early 70s cars, where they A larger engine with the proper building foundation anticipated a broad range of engine sizes being installed in can always be modified to deliver more HP. A the cars, but from about 1976 on, most of the running gear is smaller engine will be maxed out faster. marginal when any power increase is forthcoming. See Chassis – Running Gear Modification and Tuning Guide 2. Decide what the car's primary use. Street only? (published separately) for more info. Occasional trips to the strip? Trailer only? Decide as soon as possible. Remember, a 1975 442 with a 350 is not going to be a good strip car unless you have the Begin at the Beginning money of Donald Trump or Bill Gates. A 1975 Omega Too many people modify their engine without a plan. This with that 350 would be a much better choice. costs much, much more than if you get out a pencil (or use 3. Recognize what body size the engine will be installed your PC) and plan out what you are trying to do and what it’s in. When all is said and done, the engine has to move likely to cost. The best advice? weight. Thus, if you are starting out with a specific body4 1. Decide what engine block family and size you want to or you are considering an Olds but don’t have a start with right away. Most people start out modifying preference, here are our suggestions – by year. the engine that came in the car, and then realize that it . 1964 – 1972 A body: #1 = 425 (street and racing); #2 didn’t fit their needs and trash it and start over. = 350 (street) Obviously, this is an expensive way to go, but almost . 1965 – 1967 Starfire: #1 = 425 (street and racing) every gearhead has done this, not once, but a few times. Ask knowledgeable people and they will tell you . 1965 – 1977 B and C Body: #1 = 425; # 2 = 455 dozens of stories about this mistake. (street only – don’t take the big body racing - please) . 1973 – 1977 A Body: #1 = 425 and # 2 = 455 (street Here are some basic guidelines to assist you in the start and racing); #3 = 403 (street) up decision: . 1973 – 1981 X Body: #1 = 350 and #2 = 403 (street);  RPM: If you are looking to make horsepower from #3 = 425 (racing – the BB will fit) twisting the engine, use a 330/350. The 330 and . 1976 – 1980 H Body: #1 = 350 (street); #2 = 4035 350 will take the most abuse in this regard. Late (racing) - will require motor mount fabrication, but will 307s 350s, and 403s have “windows” in the main fit. bearing webs that can cause crank failure above . 1978 – 1987 A Body: #1 = 307; #2 = 350 (street); #3 = 5500 rpm. It has been said that there were 403s 4 cast without these windows for Buick and Pontiac 403 (racing) wagons with the towing package, but our staff have 4. Decide how much money you are likely to spend. never seen one. Remember, that you will likely spend double of  TORQUE: If you want tree-stump pulling torque, go whatever you decide, even if your plan. So do some for the big block. People have said that the big research on costs of parts, labor and incidentals - and block will not fit in the later (1979-1987) bodies, but since it is only 1 – 1 ½ inches wider, the staff is not convinced. If it will not fit, use a 403. Remember, it 4 Body designations/descriptions are found in the Chassis and is TORQUE that launches the car and HP that Service Manual for the appropriate year. moves it along. In the 60’s and 70’s we had an 5 The 350 diesel block can be substituted for Street Strip or Super adage: “On the street, torque talks”. Remember Modified. See Engine Section.

- 2 - Introduction – Preparation and Planning – Section 1

where possible, get quotes or written estimates. Then done (like adding forged instead of cast pistons). If you make up a budget and try like heck to stick to it. Your are restoring your Olds, this Manual will tell you how to do wallet (and any significant other) will thank you. There that and what proper NOS or NROS parts should be is a worksheet in the Section 8 that will help. used. 5. Don’t forget the chassis. It’s not as bad now as in the But if you are looking to build a "sleeper", remember that 60s and 70s, but most people still put most of their hard- many Oldsmobiles do not have the serial number on the earned dollars in the engine, and are disappointed block and heads and merely need the proper casting when the car handles like a whale or cannot get the number and the ID stamp (or tape) on the oil filler tube. power down on the strip. Remember Rules 1 - 4 above, This means you can pull the tube out of your old block and include chassis and brake modifications or at least and insert it in the new one. Remember that tip we gave simple restoration of the suspension pieces in your plan you on collecting information? Be sure to check it out Do not forget to add this pricing to your estimate. Use first. There are a ton of 1968 – 1969 442s running around the worksheet in Section 8. with 455s in them and no one is the wiser. . Use the Best Parts. Employ the best possible parts in the 6. Find out if the parts you are looking for are readily rotating assembly (crank, rods and pistons). We always available. We have repeatedly seen people base their suggest forged pistons and crank, regardless of the entire project build on a part that is so rare that even the application. There are good aftermarket connecting rods entire engineering division at Oldsmobile has never available, but the 350 and 400SS/425 and even the late heard of it. (Like 455 blocks with 4-bolt main bearing 400/455 rods will not fail in a street engine unless you are supports - of which there is no known example). Use using a blower6. the worksheet in the Section 8. . Get the Best Machine Shop. Find the best machinist your 7. Decide if there is enough information available on what money can buy to do your work. Make sure to be honest you are trying to do. Again, like parts that are not about what the engine will be used for when talking with available, the same can be said for information. Use the the builder. Street engines need different clearances than worksheet in the Section 8. racing engines. Regardless, there is a difference between a standard rebuild and a performance rebuild.7 8. Decide on what you have the skills to do and where you will need professional help. Rule One: If you can’t do it All engine blocks should be checked for cracks and damage yourself, it will cost you about $300 per hour. Rule Two: before you use them (most quality engine builders will do See Rule One. Some things take special tools, skills this as part of the build). Balance the assembly as if it were a and machinery that few have in their garage; and some race engine, regardless of the application. Prep the short things are just too sophisticated for most of hobbyists to block as if it was going to be on display at the Pebble Beach do. Be honest with yourself on this. Use the worksheet Concours. Clean, then clean again, debur, polish - and in the Section 8. even paint it with the proper type of paint. 9. The myth of high compression as a major factor in HP. This myth is especially true with today’s pump gas. A solid, well prepped short block can add 10-15% to your Engines with 8.5 – 9.5:1 are best for the fuel we have HP and TORQUE with no other changes – that’s 30 to 45 now, so unless you are building a Street/Strip or Super- HP on a 300 HP engine. Modified engine, try to stay in that CR ball park. Since most of the cars we are talking about in this Manual do Think about where your money ought to go first. not have computer controls, you will be able to run more ignition advance with a lower compression motor. Even HE ignitions will give better fuel flame burn at lower Second – The Cylinder Heads and Camshaft compression. These factors are far more important for Basics HP and torque than CR. Work on cylinder heads next. It may surprise you that what 10. Always build the best short block you can. After you’ve heads you use will affect the engine’s power more than the made all the decisions on 1-9 above, and unless you intake and exhaust manifolds slapped on those heads. are merely tweaking your current engine just to be Obviously they should all work together, but a fancy intake perky, make Step One building a new short block. manifold attached to a lousy set of heads will do worse than a lousy manifold attached to a good set of heads. Here are First – Short Block Basics some tips: Here are our suggestions: . Make your cylinder head decision based upon money . Start Fresh. Build a new short block from another block available and your intended use of the car. Rule One: while your car is still running. That way you can get it right Most street engines will be fine with a well prepared and without pulling out your current engine. This will save the proper set of factory heads. Rule Two: See Rule One. aggravation of having a lot of down time as well. If you . Treat your head rebuild just as you will treat your block are restoring a car, then you may have no choice if you rebuild. Find the best machinist your money can buy to do want matching numbers, etc. We do not recommend "fooling" judges, and if you are doing a 100 point restoration, you should err on the side of authenticity and only make mods that would have or 6 Small block: 1964-67 330 forged crank. Big block: 1965-67 400 could have been done in the year of your vehicle, building or 425 forged crank. See Block ID section. a bullet-proof block to run on the fuel we have now can be 7 See Section 03 in this Manual for specs.

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your heads8. Even stock heads can benefit from great 1973/74 manifold is the best bet. See the chart in Section machining and race level prep. Again, use quality parts. 05. W-31 and 442 valve sizes are adequate for most applications other than race only engines. (See Section A Note on Part Numbers 04 – Building Your Cylinder Heads). The difficulty with the General Motors parts numbering . Stay away from exotic rocker arm assemblies in Stock system is that parts were and are withdrawn from service and Factory Modified engines. Roller rocker assemblies and replaced with others - and then listed as the proper part, and different rocker ratios should be your last effort to but many times the specs are not the same as the original. extract more horsepower; and they can be added later. Worse, the original number is then removed in from the Roller rocker assemblies will free up some horsepower system as “no longer available”. due to less rotational friction and more accurate valve Further, in the late 1970s GM consolidated their parts opening. And different rocker ratios will open the cam system and began issuing part numbers that are consistent more, but they deliver less HP per dollar than other mods. across the entire line of brands. (Originally, each brand had . Get the car to make its maximum HP first, and then their own set of part numbers). At the time of this consider adding these pieces. Remember, these items consolidation the parts warehouse in Lansing was effectively sit on the most accessible part of the engine so they are “closed” and many of the “W” code parts were sold as scrap easy to do later. This does not mean you shouldn’t (including almost all of the W-31 and W-30 aluminum consider adjustable rockers or pushrods. (See Section manifolds)! Last, Oldsmobile is no longer in business, so 04 – Building Your Cylinder Heads). some parts will not be able to be found in the GM inventory . Decide on what camshaft you want – then back off from as they were scrapped out according to the US auto that spec a bit. Almost none of you will listen to this industry’s “10 year” rule. advice, but the biggest mistake we see is over-cammed 9 The parts numbers found in this manual are as much as engines . Most of the cam manufacturers give out good possible the original numbers from the 60s through the 80s. information on what will work best for your application – Our rationale is that when one is either looking for NOS please pay attention. Match the valve springs to the cam (New Old Stock) or NROS (New Remanufactured Old Stock) and to the engine’s useable RPM range. parts, these numbers will either be on the original box or Third - Induction System Basics what the NROS manufacturer will use for reference. In most cases, you can more easily make a relationship between the Match the induction system to the car’s primary use. Just original number and any replacement part. We have also like the cam, induction systems can hurt the car as much as noted where a later part number can be used as a than help. Engines designed for torque do not want or replacement without affecting performance (this especially respond to race type manifolds - or too much carburetor. Do applies to cams and valve train). not apply More’s Law here; (if some is good, more is better). A list of key part numbers and ID information is found in Most aftermarket single plane, single 4 barrel carb manifolds Appendices A, B and C. Good hunting. will produce better results than ALL stock factory manifolds, even for street use. That said; if you have to scrimp A Note on NROS Parts anywhere, scrimp here and use a factory 4 barrel manifold. The NROS (New Replacement of Stock) market is in full Here are some recommendations: swing. The only problem is that there may be issues of . Small Block Engines: The factory aluminum W-31 4 bbl quality in that many of the NROS parts are made off-shore. manifold is best, next is the 1968-1969 4 barrel cast iron Some parts have an even higher level of attention paid to pieces, if you are running a Quadrajet. All earlier them than the original, regardless of their origin, due to Rochester 4GC and Carter and AFB manifolds can be advances in metallurgy and machining. My advice is to machined out to accept the largest CFM model carbs. If purchase these NROS parts from reputable businesses that you need to use an EGR manifold, go aftermarket, have been around for a while and have proven their otherwise a 1973 or 74 manifold is the best bet. See the customer relationships. chart in Section 05. Three NROS vendors that we can highly recommend are as . Big Block Engines: if you are running a Quadrajet, the follows: stock manifolds used in the period 1967 through 1970 will  First is Fusick Automotive Products www.fusick.com. work fine in all street, non-race engines. Earlier 400 and Mike Fusick has many rare and almost impossible to find 425s can use their stock manifold. All earlier Rochester body, chrome and accessories available and ready to 4GC and Carter and AFB manifolds can be machined out ship. to accept the largest CFM model carbs. If you need to use an EGR manifold, go aftermarket, otherwise a  Next is Supercars Unlimited. Greg Rollin has stuck with delivering high quality engine parts for Oldsmobiles for almost 20 years. www.supercarsunlimited.com He has 8 The machinist doing the heads does not have to be the one doing cams and other NROS parts that just can't be found the block. Consider experience in building and porting Olds heads anywhere else. as a major factor. 9  Last, but not least, is Year One, www.yearone.com, who As an example, the factory supplied the 328 cam to 1968 – 1971 has been in business since the early 80s and who stick W-30’s (figuring the cars would end up on the strip). On the street this cam was too much. When both cars ran the stock 3.90 jumped into the NROS business when it was hardly rear, the auto car, with a 285/287 cam, would smoke the stick profitable, and who has grown to a legitimate giant in the car in stock trim. NROS industry.

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We owe a lot of the availability of NROS parts to the boys at can truly say that without guys like Dick, Olds performance Fusick, Supercars Unlimited and Year One. A complete would not be the same. listing of NROS and aftermarket dealers is found in Section 07. Mondello cams, rocker assemblies and oiling products are still OK, but where you can go to the original source for a product, such as pistons and the like, do so. A Note on Engine Builders

There are a lot of great engine builders out there, and one might be in your local neighborhood, but if you are looking for an engine builder who has been modifying and building

hugely successful Oldsmobile engines since the 1980's there is only one I can now truly recommend, based upon numerous complaints on Mondello, and that is Dick Miller Racing, www.dickmillerracing.com (662) 233-2301. Dick is a veteran racer turned engine builder and has forgotten more than what most others know about Olds engines So if you need a part or advice, contact Dick. We

1.1 Comparative Size, Dimensions & Specifications – Block versus Block This Section will describe the various modern Oldsmobile engines, beginning with the 1964 330 V-8, including all big blocks and ending with the 307 V-8. Below is a picture and chart showing the size and weight of the various last generation pushrod Oldsmobile V8 engines.

The dimensions are for comparative purposes only. Measurements and weights provided by the manufacturer and many not take into account valve cover redesign, exhaust headers, water pump size, and accessories, etc.

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1.2 Engine Identification The best way to identify a particular engine is by casting number. However, one needs to be able to cut down the odds by using some visual clues. The following Section will help you with this process. Use the Casting Numbers Chart(s) at the end of this Section for a more accurate breakdown.

Identifying Engines – Small Block V-8 Engines The Small Block Engine - Identification at a Glance Olds used the knowledge from the development of their 215 Aluminum engine10 to design a small block V-8 cast in iron All Small Blocks will have a deck height of 9.330". All small which became the famous 260-403 series engine. This was block engines have the distributor at the rear and the starter the second GM engine to use "thin wall" casting processes, on the left side. with the Buick 300-340 being the first. The thin wall process helped to keep the engine weight down to just over 550 lbs. 260 V8s at a Glance - The 260 can be found in all This was about 50-150 pounds less than comparably sized Cutlasses, (A-Body and G-Body) from 1975–1981. For 1975 engines being produced at that time (the Chevy small block and 1978 engines, the casting code "2A" will be found next weighed about 575 lbs and was considered a lightweight). to the oil filler tube; for 1977-1981 engines, the casting code "2B" will be found next to the oil filler tube. Cylinder head design was taken from what had been learned in the 215 program, with the rocker arms initially 307 V8s at a Glance - The 307 can be found in all using a shaft. In mid-year 1964, the heads were changed to Cutlasses, (G-Body) from 1980 – 1989. For these engines, the unique Olds stamped steel rockers riding on an the casting code "5A" will be found next to the oil filler tube. aluminum pedestal for the valves for that cylinder, which Some 307s are marked "5.0 L" or "5L" on the side of the resulted in a lightweight setup that allowed more rpms with block near the motor mount stud holes. lower valve spring pressure. 330 V8s at a Glance – The 330 can be found in all Like the 215, the small block used a significant "over Cutlasses, (A-Body) from 1964–1967 and in (B-Body) Jetstar square" design, with the bore at 3.9385" and a stroke of 88s from 1965-1967. For 1964-1966 engines, the casting 3.385”, resulting in 330 cubic inches. Later 350 and 403 code "1" or "1A" (45 lifter angle) will be found next to the oil engines used larger bores, with the 350 using a 4.057" bore filler tube; for 1967 engines, the casting code "3" will be and the 403 using a huge 4.351" bore which required found next to the oil filler tube. siamesed bore coring. 350 V8s at a Glance – The 350 can be found in all The 260 and 307 went in the other direction, still retaining Cutlasses, (A-Body) from 1968–1976 and in some (B-Body) the 3.385" stroke, but reducing the bore to 3.500" and 3.800" Delta 88s from 1968-1976. For 1968-1973 engines, the respectively. Even so, both engines were still over square. casting code "2" will be found next to the oil filler tube; for They utilized the same tooling for their cylinder heads, which 1974-1976 engines, the casting code "5" will be found next resulted in much smaller intake valves, because of the to the oil filler tube; for 1977-1980 engines, the casting code potential for valve shrouding resultant from the smaller "3B" will be found next to the oil filler tube, for 1979-1980 cylinder bores, 350 H/O engines "3A" will be found next to the oil filler tube. The 350s produced with the 3B code will have "windows" in Regardless, the small block engine was quite successful, the main saddles and are inappropriate for any high being placed in over 2.5 million vehicles including each and performance modification. every GM make, and having been produced for over 25 years. 350 Diesel V8s at a Glance - The diesel 350 can be found in some Delta 88s (B-Body), 98s (C-Body) and some Toronados from 1977-1981, as well as Pontiacs, Buicks and Cadillacs. For these engines, the casting code "D3" will be found next to the oil filler tube and the cylinder heads will be marked with "D3A". These blocks are unique to diesel engines but can be used as gasoline engines, once modified. They have main bearing journals that replicate the big block engines at 3.000”. Diesels came in 260 cu. in. versions ("D2"), but they can usually be bored safely to 350 specs. 403 V8s at a Glance - The 403 was used in Delta 88s, 98s and Toronados in the period 1977–1979. It was a very popular block and used by Pontiac in its Trans Am during that period. For 1977 engines, the casting code "4A" will be found next to the oil filler tube; for 1978-1979, the casting

330-403 V-8. This picture shows the 330 in a 1964 442. Note that the code "4B" will be found next to the oil filler tube. 403s are distributor is rear mounted, in the traditional Oldsmobile manner. marked "403" on the side of the block, near the motor mount stud holes. All 403s will have cylinder heads marked "4A" near the number 1 spark plug. 10 See Book Two of the Engine Modification and Tuning Guide for a complete history and modification information on the 215 engine. Use the Casting Numbers Chart(s) in Section 2.3 for a more A history of production and models which used the 215 is found in accurate breakdown. Oldsmobile Technical Data Sheet, published by Wild About Cars.

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Identifying Engines – Big Block V-8 Engines The Big Block Engine - Identification at a Glance Like the Oldsmobile small block, the big block drew its roots The Big Block should have a deck height of 10.625".11 All from the 215 program. Essentially, it was an expanded big block engines have the distributor at the rear and the version of the 330, with the same bore centers and even starter on the left side. crankshaft spacing. As such, and unlike any other GM engine, the big and small block can share heads, cams, 400 Short Stroke V8s at a Glance - The 400 short stroke cranks (with modification) and almost every other ancillary engines can be found in all A-Body 442 and Cutlass component. Turnpike Cruisers (which used a 2 barrel carb) from 1965– 1967. For 1965 engines, the casting code "B" will be found next to the oil filler tube; for 1966-19677 engines, the casting code "E" will be found next to the oil filler tube.

400 Long Stroke V8s at a Glance - The 400 long stroke engines can be found in all A-Body 442 and Cutlass Turnpike Cruisers (which used a 2 barrel carb) from 1968– 1969. For these engines, the casting code "G" will be found next to the oil filler tube. While these engines do have the same stroke as the 455, they cannot be bored to the 4.125" bore of the bigger block.

425 V8s at a Glance – The 425 engines can be found in some Delta 88s and all Starfires (B-Body), all 98s (C-Body) from 1965–1967, and all Toronados from 1966-1967. For

1965 engines, the casting code "A" will be found next to the oil filler tube; for 1966-1967 engines, the casting code "C" or 330-350 V-8 400-455 V-8 "D" will be found next to the oil filler tube.

455 V8s at a Glance - The 455 can be found in some Delta 400-455 V-8 compared to the 330-350 V-8. Note cast rib on front of the big 88s (B-Body), all 98s (C-Body) from 1968–1976 and all block, absent on the small block. Except for deck height & main bearing journal size, the blocks are identical in all other dimensions. Toronados from 1968-1976, and also be found in all 442s (A-Body) and some Cutlass Supremes from 1970-1975. For 1968-1974 engines (1973-1974 442s), the casting code "F" will be found next to the oil filler tube. For 1973-1976 This makes the Olds engine very versatile as many engines, the casting code "FA" or "F " will be found next to components designed for different applications, blocks and A the oil filler tube. On late 1976 engines, the casting code "L" even series (including the diesel) can be swapped into will be found next to the oil filler tube. almost all of the blocks. Use the Casting Numbers Chart(s) in Section 2.3 for a more The first iterations of the big block were released in 1965 in accurate breakdown. both 400 and 425 cubic inch configurations. The 400 was almost a "square" design with a bore of 4.000" and a stroke of 3.975". This iteration led to good torque and great horsepower, with the engines rated at 350 hp and 440 ft. lbs. of torque. Fitted to the Cutlass as the "442", it gave the muscle car parity with the GTO, its major rival. The 425 was a big car engine, found in the Delta 88, Starfire and the 98. With a bore of 4.125" and the same 3.975" stroke, it produced 375 hp and 475 ft. lbs of torque. Both engines revved well due to their lightweight valve train and did not break under abuse. In1968, the engine grew to 455 cubic inches via a stroke increase to 4.250". The 442 had to make do with a "de-bored" 455 (at 3.870"). This engine did not fare well as the smaller bore shrouded the intake valve Oil filler hole and the extra long stroke resulted in many a spun bearing when revved as the earlier 400 had been. Big blocks were produced until 1976 and are quite plentiful, The casting # can be found opposite the hole that accepts the oil filler tube at as they were the mainstay of the Olds fleet for over ten the front of the block. The "A" casting code shown here identifies this as the first offered 400-425 block with the 45 lifter angle (this block was machined years – at a time when Olds production was at its highest. to a 4.000" or 4.125" bore, as needed).

11 Deck height can be measured from the crank centerline to the top of the block in line with the center of the piston bore. This can be measured at the engine front.

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1.3 Key Specifications 1961-1978 V-8 Engines Factory Specifications - Engine Engine factory specifications, especially when it comes to horsepower and torque, are usually overly optimistic. Olds, however, seemed to be accurate in its listings, likely because its engines produced good figures in the first place. Buick, Oldsmobile and Cadillac seemed to stress torque once they were able to claim at least 300 hp, whereas Chevy and Pontiac always tended to show higher and higher horsepower outputs. The following specifications are based upon published reports, factory brochures and service manuals, factory updates, and factory technical bulletins. Where ambiguity resulted, we have chosen what appears to be the most common specification. If you have information that may counter what is published here, you may send it to the manual editors at [email protected] . Tune-up specs may be found in Section 9 - Appendix.

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- 10 - Block Basics – Section 2

Section 02 - Block Basics

2.0 Small Block 330 & 350 Block Key Differences. The key differences between the 330 and 350 are the 350’s larger bore and the Generation 1 Cast Iron Small Block V-8 Facts 330’s forged crank. General. In 1964 Olds replaced their small block 215 V8 1964 – 1966 Valve Lifter Angle. All 1964–1966 blocks used a with a cast iron block of completely new design. The 330 V- different valve lifter angle of attack on the cam (45). Thus 8 shared none of its engine block architecture with that of 1964–1966 330 blocks CANNOT USE 1967 AND LATER the 215 V-8 and the 225 V-6 sourced from Buick. The CAMS. All 1964–1966 cams WILL NOT WORK in 1967 and engine was no longer aluminum, but cast iron, as weight later blocks. Later blocks used a 39 lifter angle. Blocks with became less of a factor with the engine going into both the a “1” or “1A” cast up near the oil filler tube used the 45 lifter larger mid-sized F-85s, Cutlasses and the full-size Jetstars angle and should be avoided, if possible. introduced in that year. The engine was designed as a replacement for the 215, but was cast iron and enlarged in Early 330 Rocker Arms. The first run of 330 blocks was anticipation of the growth in size of the mid-size cars, where equipped with rocker arms similar to the previous 394 block it was to be primarily used and as the workhorse for the that traces its heritage back to 1949. These rockers had a entry-level full sized vehicles. Horsepower and torque for shaft that ran the entire length of the head to which the the 330 allowed for the engine to be installed in the full-sized rockers were attached, similar to the Aluminum 215 and Jetstars as the base engine and in 4-barrel form as the Buick engines. This is a very stable setup, but it weighs upscale powerplant. In 1968 the engine was enlarged to more and was more expensive to manufacture than the 350 cubic inches and used in 2-barrel and 4-barrel form. stamped steel rockers that are common on a 1965-1989 Olds. 1964 engines up to the engine serial number 034275 This engine was offered from 1964 through 1975, when it have these heads and should be avoided where possible. was replaced by the Generation 2 small block. This engine was offered in five flavors with displacements from 260 to Bore/Stroke. The small block does have the advantage of an 403 cubic inches. (See below). excellent bore/stroke ratio and nice, easy to oil, main bearing sizes. As such it will rev to 6500 without spinning Not So Thin Wall Casting. The 330/350 small block was bearings if proper oiling is used. It makes more than enough designed to be a “thin wall’ cast design, but because casting torque for "A", "X" and "G" body performance. cores did not have the technology we do today, Olds built a little extra in the walls of the early blocks. Thus, blocks from Bearing Diameter. The small block uses bearing sizes 1964 to 1977 can easily be bored to 0.060”. All 330s can similar to small block Chevys and thus has less bearing come out to the equivalent to a 0.060” over 350 which, for surface to oil, important as the engine rpms rise. The the 330 is 0.1815” over. We have seen 330/350s taken out connecting rod journal size is 2.125”; the main journal size is to be able to take a 425 piston (4.125”), but the block should 2.5000”. be sonic tested first. Frankly, the largest all this boring is Crankshaft. The 330 used a forged crankshaft and all others going to do is take your small block to 360 cubic inches, a did not. The forged crank will take more abuse, however the big gain in a 330, but only 10 cu. in. in a 350. If you are cast nodular iron crank in the early 350 seems to hold up looking for more cubes – go to the big block. In our opinion, well in performance work. Significant in the forged versus except for the 330, over boring should only be used to clean cast crank is that the 330 uses a different bolt up the bores. pattern than the 350. Thus, 330 and flexplates are only available in junkyards or from suppliers like Mondello and ATI. If you are scrounging a 330 block for the crank, take the flexplate too. (See the enclosed chart for the appropriate parts numbers). Pistons. Pistons in all 260 through 403 engines (except the diesel) are cast, and use the same construction. As such, they have the same pin position/size, with only the piston bore as different. This allows overbored 330s to accept

stock or aftermarket 350 pistons. However, the 330-350 blocks cannot be overbored to accept Generation 2 403 pistons, since the 403 block is siamesed. 350 diesel pistons are of a different construction and pin size. Shared Components with the Big Block. The small block engine shared many of the components of the 400/425 big block that would be introduced a year later. This included The famous “Ram Rod 350” – the 1968 W-31 package. the camshaft, rocker arms and springs, the cam bearings, The air scoops fit under the bumper. It was also offered in 1969. the distributor, the starter, oil pan and front cover and water (This system was used on the 400 W-30 and W-32 as well).

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pump. The cylinder heads will bolt on, but they contain supply and so as to use existing tooling. (Olds was the much larger ports and valves, and in most cases, these largest selling GM brand at the time). It was superseded components hurt low-end performance (see W-31 engine by the 307 in 1982. Its small 3.495" bore, but standard option, below). With machining, the cranks could be small block 3.385" stroke kept it over square, but interchanged as they are the same length, (the 330/350 severely restricted the intake valve size and resulted in utilizes 2.12" rod journals versus 2.50"; and 2.50" mains poor combustion chamber swirl12. Contrary to versus 3.00"), but there is little reason to do so as it is far expectations, it was a very inefficient engine at a time more appropriate to select the block for the engine size when fuel efficiency was paramount. The 260 did not desired. A 403 with the 3.975" 455 crank would be 480 cu. come with a 4 bbl manifold. 307 heads and intakes can in. with a 0.030" overbore, however. Interesting. be fitted, but the bores will have to be notched on the intake side. Generation 2 Cast Iron Small Block V-8 Facts . The 307: The 307 was the last Olds V8. It was actually General. This engine though so similar to the previous quite a good engine, and with the right parts can make original 330-350 in size and block design, is considered a excellent HP. It is a true 5.0 Liter engine, with a bore of Generation 3 engine because of its "windowed" main 3.800" and the 3.385" stroke. Its "windowed" main bearing webs. This change is found in all the 260, 307 and journals are its weak point. If you are looking for big 403 designs and the 350s constructed after 1976. All small horsepower from a small block, utilize a 330-350. 330 blocks after 1976, including the diesel, used ½" head bolts and 350 heads can be fitted, but the cylinder bores will 7 rather than /16". likely need to be notched for intake valve clearance, especially if the W-31 style 2.00" (or larger) valves are Thin Wall Casting. This block is truly thin wall cast, and installed. weighs as much as 25 lbs less than 1964-1976 engines. None of these blocks should be overbored more than . The 330: The 330 was the first "thin wall" cast Olds 0.030". block. It came in two flavors: an early 45 lifter angle block and a 39 lifter angle block which was common to Windowed Mains. From 1977 onward all small blocks, all later Olds engines. The 45 lifter angle block requires including the 403 were produced with “windows” in the main special camshafts and is not recommended, though if bearing journal area, which obviously affects strength and you are restoring a 1964-1966 Cutlass, cams are longevity under hard use. (Diesel blocks are an exception). available for this engine. (The original 1964 442 did For 403 owners, there are rumors of solid main journal utilize this block). 403's, cast using the pre-1977 technique. Supposedly 2500 solid main 403's were produced in 1977 - used in the large The 330 followed the Aluminum 215's "under square" Buick and Olds wagons. A solid main journal 403 can be practice, with a bore larger than stroke at 3.9385" x determined by looking at the block casting number. 403 3.385". The 330 and 350 share many common pieces, except for the crank, which is forged in the 330. This Block Casting Numbers: 557265-4A, 553990-4A, and requires a different flywheel/flexplate. The 1964-1966 554990-4A are supposed to have no “windows”. With only 2500 produced, these are a rare but beneficial find. 330 also used an intake, in 4 bbl mode that was machined for a Rochester 4GC carb rather than a Quadrajet. The later 350 Quadrajet manifold will fit. 330s Generation 2 Cast Iron Diesel 260 and 350 will take a 0.060" overbore safely and can usually be Block Facts bored to accept 0.060" over 350 pistons (for a total Diesel blocks. The diesel can be identified by a large “DX” 0.120-0.125" overbore) if desired. It is safer to stick to a cast right above the right hand center freeze plug and "D2" 0.060" overbore, however to allow fitment of 350 pistons, (260) and “D3” (350) by the oil fill tube. Diesel blocks are however. quite hefty, with 0.75” wide main bearing webs, 455 main . The 350: The 350 is a bored version of the 330 and as bearing journal sizes (which have a diameter of 3.0003” such, is greatly "over square" (4.057" x 3.385"). The 350 rather than 2.4985”); hence they run 455 main bearing caps. has the same deck height as the 300 and all other small They also have extra heft on all stressed areas, including blocks. It shares many common pieces with the 330, the cylinder walls and the block deck. This block can be except for the crankshaft and pistons. bored to 4.125” easily. Know that Olds big blocks and diesels send too much oil to the lifters, so if you intend to 350's have been over bored to accept 425 pistons use this block (good for supercharged, road race, and (0.098" for a total bore of 4.155") but for 16 cubic inches nitrous applications), see Section 3. of displacement, the only reason might be to meet a maximum engine size of 6 liters for certain racing Small Block Key Differences venues. Modifications to these engines will be covered in later . The 350 Diesel: For extreme use, the diesel block is the sections. best bet. It is cast with more deck material and has much more sturdy main journal webs. In some areas, it is Block. There are some significant differences between the small block engines. All 330 through 403 blocks use the same 9.330" deck height. 12 All Olds heads use the same valve stem center-to-center distance . The 260: The 260 was designed and built to provide of 1.910". This limits the overall combined size of the two valves, but also places the valves too far apart in the smaller bore engines for Olds A and G body vehicles without relying engines. See the chart in Section 3 to see the impact of this on other GM divisions for a small, fuel efficient engine circumstance.

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not as good as the standard 330-350 because it is cut for Cam, Heads and Valve Train. Heads, rocker arms, cam, the big block main journal size at 3.000", which means it lifters and valve springs will interchange between the all the has its own unique cast crankshaft. (A forged piece was small blocks, except for the early 1964 heads. offered from Moldex and may still be available). The larger mains mean that it does require more oil to . Heads: There are more different heads than any other lubricate these bearings, a good thing in a slow turning element except camshafts in the small block engine. diesel, but somewhat of a detriment in a high revving There were 17 different head castings during its entire small block. run in both generation 1 and 2. 1968-1970 W-31 engines featured the largest overall valve sizes with a The diesel can be overbored to as much as 0.185" and 2.00" intake valves and 1.625" exhausts with standard stroked to the 425's 3.975" stroke. If you are considering valves being 1.875" and 1.562" respectively for all 330 building a 350 diesel block, contact Mondello at and 350 engines until 1977, when the intake was www.mondellotwister.com. reduced to 1.500". The 403 ran 2.00" and 1.500". See the Head Casting Number Chart for detailed information. All heads prior to 1971 (casting code "1" – "6" have the same port configuration and runners, even if fitted with larger valves. W-31 heads "5" &"6" have exactly the same ports and only have larger valves fitted. Use the common "5" and "6" series and merely fit the larger valves, if desired. If you desire stainless valve seats, consider the 1971-1972 "7" head. 1973-1976 "8" heads ran the big block 1.625" exhaust, but used a larger combustion chamber.

260 valves used 1.500" intakes and 1.300" exhausts. 307 valves were 1.750" for the intake and 1.500" for the exhaust. 403 valves were 1.995" intakes and 1.500" exhausts. As stated, the 260 can only run 307 heads as a performance upgrade, but the 307 can run 330-350 The diesel block - showing sizeable main saddles. heads if the valves remain at non W-31 size. 403s can insert 455 exhaust valves, but should run their 4A head, . The 403: The 403 has the largest bore size of any Olds due to port and combustion chamber sizing. (See the engine at 4.351"and the small block's standard stroke of cylinder head chart in this Section). 3.385", and it used the same crank/rod combination of . Camshafts: There are quite a few selections for the the 330/350. Unfortunately, it is a true thin wall cast small block, which hit the high water mark with the W-31. block and contains the "windows" found in the 260, 307 If you are building a modified engine, the aftermarket and late 350. A main/crank girdle will help and can be stocks quite a few cams for the engine. Almost all the sourced from the aftermarket. stock spec cams are available from suppliers. Almost Consider this block unique because of its siamesed every stock spec cam is available from NROS suppliers. bores, but you may swap intake manifolds, cranks, Supercars Unlimited can supply replacement cams for heads (the 403 uses a 455 intake and 350 exhaust valve your application. www.supercarsunlimited.com. The and a big block sized combustion chamber), and cams 1985-1988 442 roller lifter cam and spring set is still from the earlier small blocks to wake the motor up. Do available from GM. www.gmpartsdirect.com. (See the keep the revs under 6200 (it will rev way past that) to chart in this Section for a listing of cams). preclude main journal flex and crank walk, a deadly combo. . Valve Train: 1964 Type "1" heads used different rocker arms and pushrods which are 8.235” long. 1964-1965 Type 1A and 2 heads (442 and B04 Police) used pushrods that are 8.3125” long, because of their

rocker/pedestal setup that was used in that head only. "1" series heads have a different angle of attack for the pushrod hole because of the 45 lifter angle of attack on the early blocks. Thus, these heads would have to have the pushrod holes bored out to 0.562" to make sure the pushrods do not bind in the hole when mounted on 1966 and later blocks (engine casting codes "2" or higher). 1964-67 Type 3 Heads used pushrods are 8.400” long, and used the typical stamped steel rockers and aluminum pedestals. Starting in 1968 all small blocks used 8.2656” length pushrods. In 1986 the 307 changed to roller lifter cams with a much longer lifter requiring 7.718” length pushrods. 307 and 350 Diesel blocks that used the 0.921" diameter roller lifter that is longer which calls for the 7.718" length pushrod.

The 403 block - showing windows in main saddles. Note the lack of "meat" in the journal area.

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All standard small blocks used valve springs with 200- forged cranks (an inexpensive fix). The same goes for the 214 lbs. open pressure at 1.270" and 84 lbs at 1.670" at 350 diesel rod. Aftermarket 350 rods will work in the 260, closed height. All W-31 engines utilized springs with 308 307, and 403, as well as with the 330 forged crank, if lbs. open pressure @ 1.270" and 108 lbs. closed modified. pressure @ 1.670". Intake Manifolds. The deck heights and heads for the 260 Starting in 1970, Oldsmobile fitted valve rotators on the through the 403 means that all of the small block manifolds keepers which increased the thickness and weight. will interchange. The W-31 aluminum 4 barrel is a good These should be removed for high performance work swap for the 330, standard 350 and the 403 engine; and because they do limit rpms. If removed, the valve spring will fit the 307 and 260, but it is a bit pricey. Aftermarket seat requires shimming as the heads spring seats were manifolds for the 330-403 will bolt to the 307 and 260, but cut deeper to compensate for the total spring assembly for the 260, a stock 307 4 bbl aluminum manifold is best height difference. Thus, 1970 and later heads should be due to the small ports and valves. checked for these deeper valve seats and shimmed as necessary to retain the proper total valve height closed. There are some excellent aftermarket manifolds for the small block. The Edelbrock Performer is a good all around Crankshaft and Rods. The crankshafts are varied in compromise. This manifold is overkill on the 260 and it is specification from engine to engine, but will interchange, as recommended that the 307 4 bbl be used if switching over all share the same rod journal size. The 330 crank is forged to a bigger carb. while the 260, 307 350 and 403 cranks are cast. All (except the diesel) use a 2.500" main journal. The 330's forged All early stock 4GC carb manifolds can have their carb air crankshaft can be successfully installed in the other small entry holes bored out to take advantage of larger 4 GC blocks with no increase in engine size, but an increase in units - or an adapter plate can be fitted. All early 330 durability, though few cast cranks will fail if properly engines can run later Quadrajet manifolds – preferably the checked and prepared. 1968-1971 units, though the rare 1967 Quadrajet manifold is a bold on fit. If EGR is required, then utilize a 1973 - The diesel crankshaft utilizes the big block's main journals, 1974 unit. so it is unique to this block. There have been instances where inserts have been fitted to the diesel block so as to Pistons and Pins. 330 and the 350 pistons can be allow the use of the 330 forged crank or the 350 cast unit, interchanged, if the 330 block is bored, with the 1968-1970 so as to reduce the amount of oiling surface on the main W-31 pistons delivering the highest compression, as they bearings for high rpm work. are flat-topped. Aftermarket 350 pistons up to 0.060" over All Olds rods are forged, with the journal fillets being can usually be installed in a 330. With the largest stock different on those utilizing the forged crank. (Best to collect bore, but with the same deck height as the 330/350, the the crank and the rods when switching over to a forged 403 is its own animal. Cast replacement pistons are piece. 403 rods are larger and stronger and can be used in available for all blocks except the 330 from Sealed Power other small blocks if rebalanced, but must be modified to fit and others. Forged aftermarket pistons are available for the 307, 330, 350 and 403, but not for the 260.

2.1 Big Block Thus the key differences are the late block’s new crankshaft Generation 2 Big Block Facts with a larger stroke of 0.275” for a total of 4.250” compared The 400-455 "big block" is really the second generation to the earlier block’s forged crank, with its stroke of 3.975”. modern Olds V8, with the Generation 1 engine being the "Rocket" introduced in 1949 and used through 1964. It is covered in a separate manual. The 1965-1976 big block will be called the "Gen 2 Big Block" to differentiate between the

original Rocket V8. The concept of the big block, as introduced in 1965, was to recast the new small block with a higher deck to allow a longer stroke.

Obviously, certain changes were made to accommodate the higher loads that would be faced. Thus, though the block is considered a "thin wall" design, it is really not, although design factors did allow it to be about 50 lbs lighter than the Gen 1 engine. 1965-1967 Blocks versus Later Engines – There was a major change made to the big block in 1968 - a stroke change from 3.975" to 4.250". On the mid sized car's engine, the longer 4.250" stroke was adapted, but the bore was reduced to 3.870" to meet the GM mandated 400 cubic inch limit. The crankshaft was metallurgy was changed from forged steel to cast nodular iron. The 400 and 455 also had the block

notched when cast to allow the rods on the longer stroke crank to clear block bores. The experimental W-43 four-valve “Hemi” of 1971 which supposedly delivered 550 HP in emissions legal street trim!

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1964 – 1966 Valve Lifter Angle. All 1964–1966 blocks used a When you are scrounging that 400/425 block for the crank, different lifter angle of attack on the cam (45 and some with take the flexplate as well. (We have included the factory a 0.921” lifter diameter rather than 0.842"). Thus 1964–1966 parts numbers for the forged items on the Block ID page). engines CANNOT USE 1967 AND LATER CAMS. And all There is a section on visual ID on a later page. 1964 – 1966 cams WILL NOT WORK in 1967 and later You will note that using a 1965–1967 400 cubic inch block engines. Later engines used a 39 lifter angle, with 0.842” with a late 455 crank will yield a 7 liter stroker, while using lifter diameter, except all 1966-1967 400 blocks and all the early crank in a 1968 -1969 400 cubic inch block will Toronado and some Starfire 425s in the same years. yield a 6.1 liter big block. If you need to sit inside a certain As stated, all 1966–1967 400s use the later lifter angle, and cubic inch limit and want TORQUE, the 374 might be for have the larger diameter (0.921”) lifter bores. Check the you. If you are looking for 425-427 cubes, stick with the block before ordering the cam. Blocks with an “A” and “B” early 425, its shorter stroke is a better bet. and with a "D" and with no drill spot cast up near the oil filler We do suggest using a 1968-1972 455 “F” casting block with tube should be avoided as they have the old 45 lifter angle the 1965-1967 425 3.975” crank if you are building a 425, as and few NROS cams are available. you won’t have to worry about valve lifter angle. It should also be noted that the late 400 and 455 blocks are notched 1965 Rocker Arms. The 1965 engine used an interim rocker to accept the 4.250” crank throw. If you wanted to upgrade a arm assembly and pushrod length that is slightly different 425 to a 455, you would need to replicate those notches in from the setup common to all later Olds V8s. Thus, "A" any 1965-1967 block. casting code heads should also be avoided due to this circumstance, as these components may be unavailable Pistons. Pistons in all big block engines are cast and use from parts suppliers. "A" heads can be converted to the later the same construction. As such, they have the same pin setup. position/size, with only the piston bore as different. This allows the early 400, which can be overbored to 4.125"

accept 425 pistons. However, while the 400 long stroke could use a 455 piston, these blocks do not seem to be able to accept the 4.125" overbore. Surprisingly, the old 400 short stroke can use the 350 piston, if overbored 0.060". Shared Components with the Small Block. The big block engine shared many of the components of the 330 block that was introduced a year earlier. This included the camshaft, rockers, & springs, the cam bearings, the distributor, the starter, oil pan and front cover and water pump. The

cylinder heads will bolt on, but they contain much smaller ports and valves, and in most cases, these components would hurt performance. With inserts, the mall block cranks could be interchanged as they are the same length, (the 330/350 utilizes 2.12" rod journals versus 2.50"; and 2.50" mains versus 3.00"), but there is little reason to do so as the best result would be a 373 cubic inch big block (3.975" crank), since the 4.250" crank throws will hit the cam. (Olds 1965 rocker arm setup, note Chevy style studs but unique pivots and did build a 373 engine for testing purposes). It is far more retainers. The 1966-1989 system was less expensive to build. This earlier appropriate to select the block for the engine size desired. system did allow easier lifter pre-load setting.

Generation 2 Big Block Key Differences Bore and Stroke. As mentioned earlier, the 1965 – 1967 engines utilize a stroke of 3.975" coupled with a forged Block. There some significant differences in each block, crank to make their displacement. Unless you are looking however all Generation 2 Big Blocks us the same 10.625" for killer cubes, this engine is a better choice for high rpm deck height. power production. . The Early 400. The 400 was designed to meet the GM- Bearing Diameter. The one critical difference in the big block mandated 400 cubic inch limitation for Intermediate cars. is the main bearing journal size, which is 3.00” versus the This was accomplished by reducing the bore of the big small block’s 2.500”. Connecting rod journals are also car's 425 by 0.125" to an even 4.00" and retaining the different, with the big block at 2.500” and the small block at 425's 3.975" stroke. Other than this, the 1965 400 2.125”. The bigger journals handle load better, but can have blocks were identical and merely used this bore and oiling issues as the RPM increases. stroke combo. All components used on the 425 will interchange. These blocks are casting code "B", Crankshaft. The early 1965-1967 engines used a forged The 1966-1967 400s were Toronado 425 clocks utilizing crankshaft. Because of balance issues, there is a significant its 39 lifter angle and 0.921" large circumference lifters difference in the forged cranks that the 400/425 used – The that were again under-bored to 400 cu. in. early cranks had a different flywheel bolt pattern than the 400 long stroke and 455. The forged crank flywheels and . The Early 425. The first 425 was a beautiful casting, flexplates are only available in junkyards or from suppliers with hardly any flash and with good tolerances, however like Dick Miller . it used the older 45 lifter attack angle and should be avoided as few factory or aftermarket cams are

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available, though Isky and Engle will grind cams for this Cams, Heads and Valve Train. Heads, rocker arms, cam, block. This block is coded "A". In most cases, you are lifters and valve springs will interchange between the all the just better off, cost wise, utilizing the 1966-67 425. big blocks, excepting the 1967 "A" heads. Valves are different sizes and ports are different from head to head and . The Late 400. This may be the best of the lot, if you are among different application, with the average intake at about looking for a 400 cu. in. engine. In fact, there were many 2.00" and the exhaust at 1.625". racers who reverted to the 1967 400 in 1968 when their long stroke 400 dumped. The casting tolerances are . Heads: There are more different heads than any other better in this block and it has the modern 39 lifter attack element except camshafts in the Gen 2 big block engine. angle, however, because of this, it may not be possible The 400 and 425 had 3 different head castings during its to bore this block 0.125" over to make a 425. Sonic test run. 1967 400 W-30 engines also featured in 2.125" the block before attempting this overbore. 1966-1967 intake valves (standard was 2.000") and 1.630" exhausts 400s 50 425 specs. These blocks are coded "E". (standard was 1.625"), which were carried over to all future W-30s. See the Head Casting Number Chart for . The late 425. There are two late 425's, the passenger detailed information. car 425 and the Toronado. Both will be coded "D", and have a "drill spot" next to the letter. Strangely, the All heads prior to 1968 (casting code "A" – "C" have the Toronado engine blocks featured the same 0.921" same port configuration and runners, even if fitted with diameter lifters as used on the 400, but the 88 and 98 larger valves. W-30 heads "D", "F", "FA, "H", "HA", "K", 425's did not, using the standard 0.842” diameter lifter in and "KA" have a raised floor and one of the heat riser their blocks. These blocks can safely handle a 0.060" passages blocked by the casting, and do flow better, but overbore, which will deliver 438 cu. in. not appreciably. The H and K series heads utilize stainless valve seats. If you can find a set in your junk . The Long Stroke 400. Offered for only two years, the yard jaunts, get them, but otherwise, use the common long stroke 400 was delivered so as to make the "C" and "E" series and "G" and "GA" (stainless seats) mandated GM 400 cu. in. limitation for intermediate cars. series. Avoid the "J" head as it does have some This was accomplished by under-boring the now restrictions. (See the chart in this Section). standard 455's 4.125" to 3.870". Unfortunately, Olds did not just take a 455 block and machine it to this lesser "A" series heads have a different angle of attack for the bore. The 400 block was cast with smaller cores, and as pushrod hole because of the 45 lifter angle of attack on such can only be overbored 0.060" safely. Some early the early blocks. Thus, these heads would have to have 1968 blocks have been bored to reach 4.000" (0.130"), the pushrod holes bored out to 0.562" to make sure the and the early 400 piston could be fitted. The net engine pushrods do not bind in the hole when mounted on 1966 size would be 428 cubic inches. All 400 long stroke and later big blocks (engine casting codes "D" with drill blocks are coded "G". spot, and "E" - "L"). . Cam: There are quite a few selections for Gen 2 Big Block, which became more interesting when the W-30 and H/O were offered. See the cam chart in this Section for details on cam specs. If you are building a modified engine, the aftermarket stocks quite a few cams for these engines. Almost all the stock spec cams are available from suppliers.

. Valve Train: Gen 2 big blocks initially adopted a valve train similar to the 1964 small block, with the 67-69

engines borrowing the rockers from the 1964 second stage small block, though they moved fairly quickly to similar rockers and pedestals that were used until the engine was discontinued in 1989. Lifters came in two sizes on early big blocks; 0.842" and 0.921" diameter. The 0.921" lifter is 0.125" TALLER than the 0.842. Thus there are two pushrod lengths fitted in these early engines. All big blocks from 1968 on had 0.842" lifters. The 455 block above clearly shows the "notches" cast in the block to allow rod clearance. 1965 400-425 pushrods are 9.6250” inches long, due to using an interim rocker/pedestal type. 1966-67 engines

using the 0.921 lifter had pushrods that are 9.4375” long, . The 455. Offered as the major big block engine from due to the usage of these longer lifters. (These engines 1968 through 1976, the 455 powered almost 2 million used a different lifter that was 0.982" in diameter and vehicles. It was cast in four different series; Sans Serif 0.125" longer. Starting in 1968 all big blocks used "F" code (1968-1970), Serif "F" code (1971-1974, with 9.5781” length pushrods because they all used the clutch ball), "FA" code (1972-1975 w/o clutch ball), and 0.842" lifter. "L" code (1976 w/o clutch ball), for motor homes and Valves were standard at 2.00" intakes and 1.629" marine applications. All 400 long stroke and 455 blocks exhausts. Starting in 1968, W-30 valves were 2.100" on are cast with "notches" for connecting rod clearance due the intake side and 1.630" on the exhaust. to the 4.250" stroke.

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All standard 400-455s used valve springs with 214 lbs. the 400 utilizing a flat-topped piece. 350 W-31 forged units ( open pressure at 1.270" and 84 lbs at 1.670" at closed available from Sealed Power) can be fitted if the block is height. 1965 High Performance (precursor to the W-30) bored 0.060" over (412 cu. in.) as all Olds V8 engines from engines ran dual springs with 315 lbs. open pressure 1964 to 1988 use the same piston pin to piston top height. and 115 lbs. closed. All W-30 cars, starting in 1966, utilized 308 lbs. open pressure springs @ 1.270" and If your 400 long stroke block is sonic tested and will support 108 lbs. closed pressure @ 1.670". a 0.130" overbore, the W-31 piston can be fitted – for a 440 cu displacement – however, the compression will be 11.5:1. Starting in 1970, Oldsmobile fitted valve rotators on the 330 and 350 low comp pistons can be fitted with the 330 keepers which increased the thickness and weight. slugs delivering a 415 displacement. In this case, the These should be removed for high performance work engine will have about a 9.50:1 compression ratio. because they do limit rpms. If removed, the valve spring seat requires shimming as the heads spring seats were Aftermarket 455 pistons up to 0.060" over can be installed in cut deeper to compensate for the total spring assembly a 425. Cast replacement pistons are available for all blocks height difference. Thus, 1970 and later heads should be except the 425 from Sealed Power and others. Forged checked for these deeper valve seats and shimmed as aftermarket pistons are available for all units from suppliers necessary to retain the proper total valve height closed. such as Dick Miller www.dickmillerracing.com. Crankshaft and Rods – All 1965-1967 big blocks used a See the chart in this Section for typical piston/head/block forged steel crankshaft with a 3.975" stroke. All 1968-1976 possibilities. big blocks utilized a cast nodular iron crankshaft with a Why Long Stroke (under square) Big Blocks were 4.250" stroke. All big blocks used 3.250" main journals and Developed. In the 60s and early 70s, the public was 2.500" rod journals. The connecting rods are almost demanding larger cars with increased weight. To meet indestructible forged steel with the 1965-1967 engine using these requirements and to offer similar or greater a 6.986" center to center length and the 1968-1976 engine performance, GM and others decided that larger, slower using 6.736" length pieces. turning engines were the easiest way to meet theses Intake Manifolds. The deck heights and heads for all the big demands. Manufacturers at that time also favored longer block engines is the same, which means that all big block stroke engines because they delivered more torque at lower manifolds will interchange. The W-30 aluminum 4 barrel is a RPM, which made for a quieter and smoother engine (and good swap for any mildly modified big engine, but it is a bit helped meet the newly mandated emissions requirements). pricey. Aftermarket manifolds are all interchangeable and Olds was forced to increase stroke because the center-to- are best fitted based upon performance criteria. We will center distance of the cylinder bores would not allow cover the best setups later on in this manual. increases in bore sizes beyond 4.125” without siamesing the There are some excellent aftermarket manifolds for the big bores (as they later did with the 403). This limitation was the block. The Edelbrock Performer is a good all around result of designing and manufacturing the block with the compromise, and the Offenhauser tunnel port (pictured) bore to bore centers of the small block, so they could be should only be used in all out drag racing situations. machined on the same assembly line. But Olds learned in 1968 with the 400 cubic inch 442, this All early stock 4GC carb manifolds can have their carb air drastically (and sometimes calamitously) increased rod side entry holes bored out to take advantage of larger 4 GC units loading on the rod bearings during high RPM and resulted in - or an adapter plate can be fitted. All early 400-425 engines spun bearings. When the 442's with the 455 appeared in can run later Quadrajet manifolds – preferably the 1968-1971 1970 the problem was reduced, as the 455's 4.125" bore units, though the rare 1967 Quadrajet manifold is a bold on stabilized the piston and reduced rod side loading. The fit for the early cars if the original hot air style choke is net/net was that the 455 was designed more as a slow desired. If EGR is required, then utilize a 1973 - 1974 unit turning luxury car engine, not as a performance true piece. big block unit, though it is heavy and not too efficient. By utilizing the different bore and stoke combinations Pistons and Pins. Early 400 and the 425 pistons can be available, big blocks can end up with a few engine sizes interchanged, if the 400 block is bored 0.125. All early big beyond that of the factory offerings. The table below shows block pistons delivering high compression at 10.25:1, with all possibilities.

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2.2 Crankshaft Identification Crankshaft Identification – Forged Cranks The following chart, with the diagrams and pictures will assist you in identification of Oldsmobile forged crankshafts.

For about the first month of production, the Olds 455 received a forged steel crankshaft (Casting number 400943). After the first month, only cast iron cranks were used. Turn crank until you notice that the opposite two bolt holes do not line up across from one another. If you turn the crank until one of the holes that does not line up is to the right, the opposite hole will be ABOVE the centerline of the opposite hole.

Late 1964 - 1967 330 forged steel cranks have the number The early (forged) crank flange - showing two holes "388-776" on the last throw of the crank by the rear main. that do not line up on the left and right.

Flexplate ATI Transmissions www.atiperformanceproducts.com (part number 915563) and Mondello www.mondellotwister.com carry a SFI approved flexplate for the 330-425 engines Specify engine block.

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Crankshaft Identification – Cast Cranks The following chart, with the diagrams and pictures will assist you in identification of Oldsmobile cast crankshafts.

Turn crank until you notice that the opposite two bolt holes do not line up across from one another. If you turn the crank until one of the holes that does not line up is to the right, the opposite hole will be BELOW the centerline of the opposite hole.

1968 – 1972 455 nodular iron cranks will have the number "397363" on the last throw of the crank by the rear main. The crank will display a "NAK" or "N" as shown above. The late (cast) crank flange - showing two holes that do not line up on the left and right.

Flexplate ATI Transmissions www.atiperformanceproducts.com (part number 915565) and Mondello www.mondellotwister.com carry a SFI approved flexplate for the 330-425 engines Specify engine block.

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