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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 and the Generation 1 Small Block V-8 Facts 330’s forged . General. In 1964 Olds replaced their small block 215 V8 with 1964 – 1966 Valve Lifter Angle. All 1964–1966 blocks used a a cast iron block of completely new design. The 330 V-8 different valve lifter angle of attack on the (45). Thus shared none of its block architecture with that of the 1964–1966 330 blocks CANNOT USE 1967 AND LATER 215 V-8 and the 225 V-6 sourced from Buick. The engine . All 1964–1966 cams WILL NOT WORK in 1967 and was no longer aluminum, but cast iron, as weight became later blocks. Later blocks used a 39 lifter angle. Blocks with less of a factor with the engine going into both the larger a “1” or “1A” cast up near the oil filler tube used the 45 lifter 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 , 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 the shaft that ran the entire length of the head to which 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 . This is a very stable setup, but it weighs upscale powerplant. In 1968 the engine was enlarged to 350 more and was more expensive to manufacture than the 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/. The small block does have the advantage of an 403 cubic inches. (See below). excellent bore/ and nice, easy to oil, 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 journal size is 2.125”; the main journal size is to be able to take a 425 (4.125”), but the block should 2.5000”. be sonic tested first. Frankly, the largest all this boring is . 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 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 , rocker arms and springs, the cam bearings, The air scoops fit under the bumper. It was also offered in 1969. the , the , 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 heads will bolt on, but they contain much supply and so as to use existing tooling. (Olds was the 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 valve size and resulted in utilizes 2.12" rod journals versus 2.50"; and 2.50" mains poor 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 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 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 use this block (good for supercharged, road race, and pistons (0.098" for a total bore of 4.155") but for 16 cubic nitrous applications), see Section 3. inches 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 not 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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as good as the standard 330-350 because it is cut for the Cam, Heads and Valve Train. Heads, rocker arms, cam, big block main journal size at 3.000", which means it has lifters and valve springs will interchange between the all the 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 2.00" . The diesel can be overbored to as much as 0.185" and intake valves and 1.625" exhausts with standard valves stroked to the 425's 3.975" stroke. If you are considering being 1.875" and 1.562" respectively for all 330 and 350 building a 350 diesel block, contact Mondello at engines until 1977, when the intake was reduced to www.mondellotwister.com. 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 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 (left) and 307 (right) blocks - showing windows in main saddles. Note the lack of "meat" in the journal area. 307 actually has more!

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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 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 1973-1974 The diesel crankshaft utilizes the big block's main journals, 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 '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 early block before ordering the cam. Blocks with an “A” and “B” 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 the from parts suppliers. "A" heads can be converted to the later 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 did build 1965 setup, note Chevy style studs but unique pivots and a 373 engine for testing purposes). It is far more appropriate retainers. The 1966-1989 system was less expensive to build. This earlier 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 for however all Generation 2 Big Blocks us the same 10.625" killer cubes, this engine is a better choice for high rpm power deck height. 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 blocks 2.125”. The bigger journals handle load better, but can have were identical and merely used this bore and stroke oiling issues as the RPM increases. 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, with flexplates are only available in junkyards or from suppliers hardly any flash and with good tolerances, however it like Dick Miller. used the older 45 lifter attack angle and should be avoided as few factory or aftermarket cams are available,

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though Isky and Engle will grind cams for this block. This Cams, Heads and Valve Train. Heads, rocker arms, cam, block is coded "A". In most cases, you are just better off, lifters and valve springs will interchange between the all the 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 to The 400 and 425 had 3 different head castings during its bore this block 0.125" over to make a 425. Sonic test the run. 1967 400 W-30 engines also featured in 2.125" block before attempting this overbore. 1966-1967 400s 50 intake valves (standard was 2.000") and 1.630" exhausts 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 car detailed information. 425 and the Toronado. Both will be coded "D", and have a "drill spot" next to the letter. Strangely, the Toronado All heads prior to 1968 (casting code "A" – "C" have the engine blocks featured the same 0.921" diameter lifters same port configuration and runners, even if fitted with as used on the 400, but the 88 and 98 425's did not, using larger valves. W-30 heads "D", "F", "FA, "H", "HA", "K", the standard 0.842” diameter lifter in their blocks. These and "KA" have a raised floor and one of the heat riser blocks can safely handle a 0.060" overbore, which will passages blocked by the casting, and do flow better, but 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 long yard jaunts, get them, but otherwise, use the common stroke 400 was delivered so as to make the mandated "C" and "E" series and "G" and "GA" (stainless seats) GM 400 cu. in. limitation for intermediate cars. This was series. Avoid the "J" head as it does have some accomplished by under-boring the now standard 455's restrictions. (See the chart in this Section). 4.125" to 3.870". Unfortunately, Olds did not just take a 455 block and machine it to this lesser bore. The 400 "A" series heads have a different angle of attack for the block was cast with smaller cores, and as such can only pushrod hole because of the 45 lifter angle of attack on be overbored 0.060" safely. Some early 1968 blocks have the early blocks. Thus, these heads would have to have been bored to reach 4.000" (0.130"), and the early 400 the pushrod holes bored out to 0.562" to make sure the piston could be fitted. The net engine size would be 428 pushrods do not bind in the hole when mounted on 1966 cubic inches. All 400 long stroke blocks are coded "G". and later big blocks (engine casting codes "D" with drill 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 . The 455. Offered as the major big block engine from 1968 using the 0.921 lifter had pushrods that are 9.4375” long, through 1976, the 455 powered almost 2 million vehicles. due to the usage of these longer lifters. (These engines It was cast in four different series; Sans Serif "F" code used a different lifter that was 0.982" in diameter and (1968-1970), Serif "F" code (1971-1974, with clutch ball), 0.125" longer. Starting in 1968 all big blocks used "FA" code (1972-1975 w/o clutch ball), and "L" code 9.5781” length pushrods because they all used the (1976 w/o clutch ball), for motor homes and marine 0.842" lifter. applications. All 400 long stroke and 455 blocks are cast Valves were standard at 2.00" intakes and 1.629" with "notches" for connecting rod clearance due to the exhausts. Starting in 1968, W-30 valves were 2.100" on 4.250" stroke. the intake side and 1.630" on the exhaust.

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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 engine These should be removed for high performance work will have about a 9.50:1 . 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 these indestructible forged steel with the 1965-1967 engine using requirements and to offer similar or greater performance, a 6.986" center to center length and the 1968-1976 engine GM and others decided that larger, slower turning engines using 6.736" length pieces. were the easiest way to meet theses demands. Intake Manifolds. The deck heights and heads for all the big Manufacturers at that time also favored longer stroke block engines is the same, which means that all big block engines because they delivered more torque at lower RPM, manifolds will interchange. The W-30 aluminum 4 barrel is a which made for a quieter and smoother engine (and helped good swap for any mildly modified big engine, but it is a bit 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 "388-776" on the last counter weight of the The early (forged) crank flange - showing two holes 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 .

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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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2.3 Factory Specifications V-8 Engines Factory Specifications – Block Info 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 is better than what is here, you may send it to the manual editors at [email protected].

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Factory Specifications – Head Info 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 is better than what is here, you may send it to the manual editors at [email protected].

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Factory Specifications – Head Info Continued

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Factory Specifications – NOS Camshafts and Valve Springs 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 id better than what is here, you may send it to the manual editors at [email protected].

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Factory Specifications – NOS Camshafts and Valve Springs Continued

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Factory Specifications - NROS Camshafts and Valve Springs The following represent vendor(s) who have shown the ability to deliver quality parts meeting or exceeding OEM specifications. Other manufacturers may deliver equivalent parts; however we have no feedback or hands-on experience with their offerings.

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Factory Specifications - NROS Camshafts and Valve Springs Continued

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