DOCSLIB.ORG

Installed Height, Open Pressure and Coil Bind

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Installed Height, Open Pressure and Coil Bind VALVE SPRINGS BY MIKE MAVRIGIAN In this article, we’ll try to cover the the spring can travel before reaching basics of performance valve springs, coil bind. If installed height increas- in terms of dimensions, selection ad- es, spring tension will decrease, but vice, handling precautions and more. the spring travel will increase before Consider this somewhat of a basic reaching coil bind. overview of valve spring technology. The valve spring needs to have enough travel (from closed-valve INSTALLED HEIGHT, OPEN installed height to a safe margin PRESSURE AND COIL BIND before coil bind) to suit the valve Valve spring installed height refers lift created by the camshaft lift and to the dimension measured from the rocker arm ratio. The safety margin bottom of the spring retainer (where (full travel before coil bind) should the top of the outer spring contacts be kept at a minimum of 0.060”. the retainer) to the spring pocket in Valve spring open pressure the cylinder head, when the valve is represents the pressure (in psi) that’s closed. placed against the spring retainer Installed height affects spring at maximum valve lift. You need tension, and is the determining fac- enough pressure to control the lifters tor of what the spring closed tension as they accelerate up the cam lobe will be. The camshaft specification and when decelerating when ramp- card will list the suggested spring ing down past the lobe peak (when installed height for that cam with the the valve changes direction from cam maker’s recommended springs. opening to closing). If the spring For example, if the card notes that doesn’t provide enough open pres- a specific valve spring part number sure, the lifter can bounce over the should be installed at 105 lbs at cam lobe (valve float), resulting in 1.700”, that means that if the spring the lifter smacking into the closing is installed at a height of 1.700”, this ramp of the lobe, potentially reduc- should place 105 lbs of tension with ing cam lobe and lifter life. the valve closed. Never assume that Open spring pressure is a func- this is correct. Always check this on tion of the combination of spring a bench-mounted valve spring tester. rate, net valve lift and seat pres- Changing installed height will sure. Excessive open spring pressure affect spring tension. If you need results in stresses placed on the to reduce installed height, you can pushrods and in turn, valve bounce. place a shim (of the needed thick- Lighter valves require lower spring ness) under the spring, or you can pressures, which reduces the risk of use a different design retainer with a pushrod flexing. shallower dish (using a retainer with Valve spring coil bind takes place a deeper dish will increase installed when the spring is compressed to a height). You can also use a valve point where the coils contact each lock that id designed to change the other. You can measure coil bind retainer height location. height by placing a retainer on top As the installed height is de- of the spring, and compressing the creased, spring tension will increase. spring (carefully) until the coils This also reduces the distance that touch each other. The distance from 18 APRIL-JUNE 2015 engine professional EP Q215 1-96.indd 18 3/20/15 10:09 AM Example of basic valve spring layout and applicable dimensions. (illustration courtesy PAC Racing Springs) Example of coil bind determination. Installed height of this spring is 1.950”. When we subtract combined valve lift (minus lash) of 0.785”, we determine a coil bind height of 1.105”. This provides a safety clearance of 0.060” to avoid coil bind. (illustration courtesy PAC Racing Springs) the bottom of the retainer to the bottom the cylinder head (remember to dedicate of the spring is the coil bind height. each valve to each valve location in each Subtract the coil bind height from head…that way, once measured and the installed height. The result is the clearanced, you know that the particular maximum spring travel. The standard valve will fit properly in a specific loca- recommendation to provide a safety tion. Don’t assume that you can mix up margin is to have a minimum of 0.060” the valves). With the valve fully inserted spring compression travel greater than into the (intake or exhaust) location, the full lift of the valve. If the coils bind, with the valve fully seated, install locks this creates a dead-stop during valvetrain and the retainer. Pull up on the retainer operation, so something’s gotta give, in- and measure the distance between the un- cluding potential pushrod bending, lifter derside of the retainer (where the spring or cam damage or rocker arm failure. contacts the retainer) to the spring seat. The use of a bench spring tester offers If you’re using hardened spring seats, be a convenient method of pre-determining sure to install for this check. coil clearance. Reference the spring’s Remove the spring from the head and installed height. Install the valve into place the spring on the tester. Compress www.engineprofessional.com 19 EP Q215 1-96.indd 19 3/20/15 10:09 AM valve SPRINGS BY MIKE MAVRIGIAN This valve features a square-cut groove. Only a square-key lock will work here. Never assume that your locks (keepers) are correct for the valves at hand. Installing the incorrect style locks will lead to disengagement (locks This valve features a radius lock groove. You need to pay attention to this. Only and retainers popping off), which can lead to a very quick catastrophic valve a “beadlock” style lock (keeper) will work with this type of groove. failure, including bashed pistons. This closeup shows a typical beadlock style valve lock. Only use this style if This is a square-cut lock. Again, this will only work with a valve that features a the valve features a radius groove. square-cut groove. This may sound very basic, but it’s easy to make a mistake if you’re not paying attention during valve/spring assembly. to the afore-measured height. The pres- duced cylinder pressure (reduced power) pressure and/or oil thickness is increased, sure tester will display the seat pressure but this can also result in deforming valve spring pressure must be increased at that installed height. (tuliping) the valve head, to the point as well in order to maintain lifter control Reference the maximum (gross) lift where the head can actually snap off of and to prevent pumping up. So, if your of the valve, based on your cam lift the stem. engine is supposed to use, say, 10W-30 and rocker arm ratio. The difference With hydraulic lifters, the springs oil and you move up to a straight 50W between the two measurements should need to place enough pressure at the oil, you’re not doing the engine any indicate how much additional travel is valve lifter to keep the lifter plunger cen- favors. Thicker is not always better. available to the spring. For example, if tered in its travel to prevent lifter “pump A common misconception involves the installed height of the valve spring up.” Pump-up causes the valve to be the belief that higher spring pressures is 2.000”, and the maximum lift of the held slightly off of its seat, which reduces reduce horsepower, due to the increased valve is 0.5000”, the open spring height power and can also be mis-diagnosed as resistance of the springs. What we need should be 1.500”. a misfire (with resulting misplaced blame to bear in mind is that for every valve Sufficient seat pressure is needed to on the ignition or fuel system). that is opening and the spring being com- keep the valves from bouncing when Unnecessarily high oil pressure and/ pressed, another valve is closing and its they return to their seats (valves closed). or higher-than-necessary oil viscosity valve spring is expanding. This expansion Bouncing valves results in not only re- can cause hydraulic lifter pump-up. If oil force actually returns the energy to the 20 APRIL-JUNE 2015 engine professional EP Q215 1-96.indd 20 3/20/15 10:09 AM Engine-Professional-2015_Q2 2/24/2015 2:42 PM Page 1 valve SPRINGS BY MIKE MAVRIGIAN valvetrain and the engine, resulting on Hydraulic roller cams/lifters require can use springs in the 450 lb range Ensure zero horsepower loss. This phenomenon higher spring seat pressures in order to (again, here we’re referring to also ob- is referred to as the valvetrain’s regen- control the heavier roller lifters, as well taining decent valvetrain life/durability). erative characteristic. In short, when in as to control the more aggressive opening Open spring pressures that exceed doubt, run slightly more spring seat pres- and closing rates common to roller cams. 360 lb open pressure should really be Maximum What sure, not less. Small block engines generally require mated with billet steel roller lifter bodies seat pressures in the 120 –145 lb range. (not OE-level cast iron roller lifter bod- is coil TIPS ON CHOOSING VALVE SPRINGS Big block engines usually need seat ies). Flat-tappet cam/lifters for street and pressures in the range of 130 – 165 lb. Solid lifter roller cams/lifters are Performance bind street/strip: General-purpose street small block generally reserved for race applications Small block engines will generally engines with hydraulic roller cams or “serious” street/strip use. Solid lifter and require 105 – 125 lb seat pressure require at least 260 lb open pressures roller cams are designed with more aggressive opening and closing rates, re- With Valve how is it measured? Big block engines (due to heavier for applications up to about 4000 valves) usually require 115 – 130 lb seat rpm.
Load more

Recommended publications
  • Valvetrain Repair - Fixing Valve Float Diagnosing Valve Float Issues Found in an Engine from the February, 2009 Issue of Circle Track Magazine by Jeff Huneycutt
    Valvetrain Repair - Fixing Valve Float Diagnosing Valve Float Issues Found In An Engine From the February, 2009 issue of Circle Track magazine By Jeff Huneycutt While making our usual rounds of shops, we came across a problem that plagues many rebuilders and unnecessarily costs them lots of money-and we thought we'd share the solution with you. While performing a rebuild of a late-model Chevy engine, cylinder head specialist Kevin Troutman of KT Engine Development saw the telltale signs of classic valve float. The customer either didn't notice or just didn't bother to mention the problem to KT Engines, and the results were costly. But the good news is that valve float can be avoided. Valve float occurs when the valve springs are incapable of holding the valvetrain against the camshaft lobe after peak lift. This happens when either the weight of the combined valvetrain components or the rpm speed of the engine creates so much inertia that the spring is no longer able to control the valve. The most common response to valve float is to increase the strength of the spring so that it can better control valve motion. But stronger springs generally weigh more and cause their own problems. Achieving the optimum strength-to-weight ratio is a delicate balancing act for every engine builder. The most efficient and dependable engines are able to hit the sweet spot in the triangle created between strength of the valve spring, weight of the valvetrain components (lifters, pushrods, rocker arms, valves, retainers, locks, and springs), and the engine's peak rpm levels.
    [Show full text]
  • 2000 December
    m / wont settle rot J because they're They know the WeMcraft rim-he on a TIG Torch means local distributor support no matter where you are2 Sure, you can save a few bucks with something less - but when it counts wouldn't you feel better knowing a Weldcraft distributor is ~ nearby and ready to help? Weldcrafi TIG Torches, because every weld you make counts. Call today for your ! % FREE copy of o Weldcrafi's new d t % Mini-Catalog I~ and find ~2~ ....... J f ~,q~ out how easy it is to get dm~ 1~ k the support the smart J mone,~, counts on in your l~ands. WELDC'RAFr A division of DovaTech, Ltd. 4~9 West Coming Road Beecher, Illinois 60401-0667 800.924.8575 ~wvdovatech.com Circle No. 4 on Reader Info-Card A ~ INDUSTRIESCOMPANY THE BEST FLAW DETECTOR JUST GOT BETTER Using the latest advances in technology, Panametrics has engineered a very powerful digital ultrasonic flaw detector- the fourth generation - EPOCH 4. The EPOCH 4 provides the ultimate combination of unsurpassed ultrasonic performance, simplicity of operation, and scope of documentation capabilities. New key features include customizable narrowband filtering, a tunable square wave pulser, and a high PRF rate up to lkHz. Its light weight of 5.4 Ibs (2.4 Kg)including a high-power NiMH battery, new large high resolution Liquid Crystal Display (LCD) or Electroluminescent Display (ELD), and ease of transducer calibration are unmatched by any other portable flaw detector. • Customizable narrowband filtering • Selectable, tunable square wave pulser or spike excitation pulser • Selectable PRF from 30Hzto optional lkHz • VGA output for large screen viewing • High-power NiMH battery • Large, bright, high resolution ELD or LCD with full/split screens • Easy, automated transducer calibration • Extensive alphanumeric datalogger with editing capability • Extensive memory capacity to 360 wave- forms/12,000 thickness/400,000 B-Scan readings • Expandable memory to 720 waveforms/24,000 thickness readings • Lighter, more ergonomical design (5.4 Ibs/2.4 Kg) • lime-of-flight measurement in microseconds Circle No.
    [Show full text]
  • Marvel-Schebler-Manual.Pdf
    SERVICE MANUAL for MARVEL-SCHEBLER TRACTOR and INDUSTRIAL CARBURETORS MODELS DLTX & TSX MARVEL-SCHEBLER PRODUCTS DIV. BORG-WARNER CORPORATION DECATUR, ILL, USA. 2 Principle of Operation Marvel-Schebler Carburetors are used on thousands of tractor and industrial engines and have been designed to provide many years of trouble-free service, however, as in the case of all mechanical devices, they do in time require proper service and repairs. An understanding of their construction and how they operate as well as an understanding of their function with respect to the engine will not only avoid many false leads on the part of the serviceman in diagnosing so-called carburetor complaints but will create customer satisfaction and a profitable business for the progressive service shop. To understand a carburetor, it is necessary to realize that there is only one thing that carburetor is designed to do and that is to mix fuel and the air in the proper proportion so that the mixture will burn efficiently in an engine. It is the function of the engine to convert this mixture into power. There are three major factors in an engine which control the change of fuel and air into power: 1. Compression. 2. Ignition. 3. Carburetion. Carburetion has been listed last because it is absolutely necessary for the engine to have good compression and good ignition before it can have good carburetion. When the average person thinks of “carburetion” they immediately think of the carburetor as a unit. Carburetion is the combined function of the carburetor, manifold, valves, piston and rings, combustion chamber, and camshaft.
    [Show full text]
  • TR250/TR6 Carbs Part I
    2/21/2019 TR250/TR6 Carbs Part I TR250 - TR6 Carburetor Overhaul Part I - Disassembly & Theory These notes were initially prepared and published as a three part series in the Buckeye Triumphs Newsletter in late winter & early spring of 2001 and then placed on the Buckeye Triumphs website. Over the next six months input and useful suggestions were received from a number of folks. I also rebuilt several more carb sets and realized that the information could be clarified in a number of places. The carbs originally described in these notes were powder coated, which required the carbs be taken apart again and further disassembly of the temperature compensators, bypass valves and float chamber vent valves. Some problems were encountered tuning the powder coated carbs. These problems caused a review the previous suggested tuning procedures. Turns out the procedures were correct, the problem was in another area of the engine. I decided to revise the notes to work in the additional information, corrections and suggestions and add parts describing how to powder coat the carbs and how to install adjustable needles in the early non-adjustable carbs. Hopefully someday I'll be able to add a part describing how to replace the throttle shaft bushes and a part on the use of exhaust gas sensors. NAR 11/2001. Another update: I built an air/fuel monitor and used it to tune the carbs described in Parts I, II & III. The use of the monitor provided considerable insight into the operation of the carbs. However, the optimum adjustment determined from using the monitor was the same as determined earlier without the monitor (see Part III).
    [Show full text]
  • 4. Fuel System
    f'G?\HONDA NUSO· NUSOM 4. FUEL SYSTEM 4-1 FLOAT LEVEL INSPECTION 4-5 TROUBLESHOOTING 4-1 CARBURETOR INSTALLATION 4-6 I THROTTLE VALVE DISASSEMBLY 4-2 THROTTLE VALVE INSTALLATION 4-6 I CARBURETOR REMOVAL 4-3 REED VALVE 4-8 i FLOAT/FLOAT VALVE/JETS 4-3 FUEL FILTER AND TANK 4-9 DISASSEMBLY 10I JETS/FLOAT VALVE/FLOAT 4-5 I ASSEMBLY I SERVICE INFORMATION GENERAL ciJution when working with gasoline. Always work in il well·ventilated area ;Jnd 'lway from sparks or fjarnes. VVhen disassemblmg fuel system parts, nOtC the locations of the a·rings. Replace them with new oncs during assembly. Bleed air from the OJI outlet line whenever it is disconnected. 5PECIFICATlONS _ L:,enlUri __ r__ I' ! Identifrcation number r, PA13E I Float 12.2 ± 1.0 mm (0,48 -! 0.04 in) ! Ail' screw opening 2 turns Qut lelle spl1ed 1.800 ± 150 rpm I Throllie grip free play 2-6 mm 1118-1/4 in) TOOL Floin level Gauge 0740 I 10000 TROUBLESHOOTING Engine cranks but won'! start lean mixture 1, No fuel in lank 1. Carburetor fuel jets clogged 2, Clogged lube 2. Fuel Cilp vent clogg\!d 3. Clog(Jcd fllcl stri!!rW! 3. Clogged fuel filter 1. Too much fuel getting to cylinfJer 4. Fuel line kinked (}r restricted 5. CI09!/cd ail' cleaner 5. Float valve faulty 6. F(lulty control box 6. Float level tOO low 7. Air lIent tuhe clogged Engine Idles IO(l9hly, Of' runs poorly Rich 1. Idle speed incorrect 1. Faulty float vallie 2 Rtch t1)tXtllHl 2.
    [Show full text]
  • Poppet Valve
    POPPET VALVE A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide. In most applications a pressure differential helps to seal the valve and in some applications also open it. Other types Presta and Schrader valves used on tires are examples of poppet valves. The Presta valve has no spring and relies on a pressure differential for opening and closing while being inflated. Uses Poppet valves are used in most piston engines to open and close the intake and exhaust ports. Poppet valves are also used in many industrial process from controlling the flow of rocket fuel to controlling the flow of milk[[1]]. The poppet valve was also used in a limited fashion in steam engines, particularly steam locomotives. Most steam locomotives used slide valves or piston valves, but these designs, although mechanically simpler and very rugged, were significantly less efficient than the poppet valve. A number of designs of locomotive poppet valve system were tried, the most popular being the Italian Caprotti valve gear[[2]], the British Caprotti valve gear[[3]] (an improvement of the Italian one), the German Lentz rotary-cam valve gear, and two American versions by Franklin, their oscillating-cam valve gear and rotary-cam valve gear. They were used with some success, but they were less ruggedly reliable than traditional valve gear and did not see widespread adoption. In internal combustion engine poppet valve The valve is usually a flat disk of metal with a long rod known as the valve stem out one end.
    [Show full text]
  • Carb Cleaning 101
    WWW.SOHC4.NET Carb Cleaning 101 By Mark Shively Original publication source unknown The elements of internal combustion engines are: correct fuel/air ratio, spark at right time, adequate cylinder compression. There are many passageways and openings to check and clean. All are important in function and when obstructed or not working properly, have subtle to radical effects on engine performance. Vacuum leaks and carburetor synchronization also have effects on performance and should be inspected and adjusted following the below procedures. Carb Cleaning 101 Warning: Remove all rubber parts before you begin. These parts usually include vacuum diaphragms, needle valves, o'rings, hoses, and other parts. Spray cleaners will damage these parts. Do not disassemble individual carbs from the carb bracket. Air & Fuel Passageways: Trace and learn individual fuel and air circuits from beginning to end. Machines can only drill straight through the cast passageways. To change direction, another angled passageway must be drilled. The union is plugged with a brass or bronze bead. Inspect and clean each passageway with spray cleaner, brushes/pipe cleaners/etc, and compressed air. Remove any discoloration and debris. Look for spray cleaner to exit from one or more passageways. Jet Cleaning: Inspect jets by holding to light and look through them. You should see an unobstructed round hole. Clean the jets with one or more of the following: jet cleaning wires, soak solutions, carb spray cleaners and compressed air. Re-inspect jets after cleaning and install when clear of obstructions. Some main jets have paper-like gaskets. Most have metal spacers between the jet and the emulsion tube.
    [Show full text]
  • Desmodromics Mick Walker Explains How Ducati Beat Tbe World with Spring-Less Valve Operation
    og , Desmodromics Mick Walker explains how Ducati beat tbe world with spring-less valve operation HE WORD desmodmmic wil! not be the bounce and get a higher-revving engine successful and was not developed, but in found in the Oxford or any other - in theory. the 1920s several other manufacturers tried T English dictionaries. It was coined This had been known since the early days variants of it. One layout, the Vagova, from two Greek words, meaning 'controlled of the internal combustion engine but for utilized a cam track embodying inner and run' and its mechanical function is to elimi- many years no designer managed to success- outer cam forms which guided a roller nate one of the phenomenon of valve float, fully harness it. One of the first examples of attached to one end of a 'rocker', the other or 'bounce'. This happens at high revs when completely positive mechanical valve oper- end of the rocker was forked to embrace the valve springs are unable to respond ation was used by the French Delage concern the valve stem. To provide the required quickly enough to close the valve back on in its grand prix car of 1914 - and the freedom for seating, the pivot of the rocker their seats. 11le desmodromic idea was to French knew the method as desmod- was given a small amount of spring-Ioaded replace troublesome springs with a romique. float parallel to the valve axis. me(\. jcal closing system much like that The Delage engine employed four valves Alternative methods investigated were to usedló open them.
    [Show full text]
  • PLUMBING DICTIONARY Sixth Edition
    as to produce smooth threads. 2. An oil or oily preparation used as a cutting fluid espe cially a water-soluble oil (such as a mineral oil containing- a fatty oil) Cut Grooving (cut groov-ing) the process of machining away material, providing a groove into a pipe to allow for a mechani cal coupling to be installed.This process was invented by Victau - lic Corp. in 1925. Cut Grooving is designed for stanard weight- ceives or heavier wall thickness pipe. tetrafluoroethylene (tet-ra-- theseveral lower variouslyterminal, whichshaped re or decalescensecryolite (de-ca-les-cen- ming and flood consisting(cry-o-lite) of sodium-alumi earthfluo-ro-eth-yl-ene) by alternately dam a colorless, thegrooved vapors tools. from 4. anonpressure tool used by se) a decrease in temperaturea mineral nonflammable gas used in mak- metalworkers to shape material thatnum occurs fluoride. while Usedheating for soldermet- ing a stream. See STANK. or the pressure sterilizers, and - spannering heat resistantwrench and(span-ner acid re - conductsto a desired the form vapors. 5. a tooldirectly used al ingthrough copper a rangeand inalloys which when a mixed with phosphoric acid.- wrench)sistant plastics 1. one ofsuch various as teflon. tools to setthe theouter teeth air. of Sometimesaatmosphere circular or exhaust vent. See change in a structure occurs. Also used for soldering alumi forAbbr. tightening, T.F.E. or loosening,chiefly Brit.: orcalled band vapor, saw. steam,6. a tool used to degree of hazard (de-gree stench trap (stench trap) num bronze when mixed with nutsthermal and bolts.expansion 2. (water) straightenLOCAL VENT.
    [Show full text]
  • Chapter 5 Test
    Chapter 5 Test Multiple Choice Identify the choice that best completes the statement or answers the question. ____ 1. For every complete revolution of a four-stroke cycle diesel engine how many revolutions of the camshaft take place? a. one half c. two b. one d. four ____ 2. Technician A says that camshaft rotation must be in the same direction as crankshaft rotation. Technician B says that camshaft rotation may be opposite to crankshaft rotation. Who is right? a. Technician A only c. Both A and B b. Technician B only d. Neither A nor B ____ 3. Which of the following terms is used to describe the shortest radial dimension of a cam profile? a. inner base circle c. lift flank b. outer base circle d. unload flank ____ 4. Which of the following terms is used to describe the largest radial dimension of a cam profile? a. inner base circle c. lift flank b. outer base circle d. unload flank ____ 5. If a cam profile is described as being mostly outer base circle, what would be true of the train it actuates? a. actuated twice per revolution c. loaded for most of the cycle b. actuated every other revolution d. unloaded for most of the cycle ____ 6. Which of the following is NOT found in medium and heavy duty truck diesel engines? a. cast iron solid lifters c. roller type cam followers b. middle alloy steel solid lifters d. hydraulic lifters ____ 7. When a valve cam ramps from base circle to outer base circle, what is happening to the valve? a.
    [Show full text]
  • Camshaft Installation and Degreeing Procedure
    1 INSTRUCTIONS Camshaft Installation and Degreeing Procedure Thank you for choosing COMP Cams® products; we are proud to be your manufacturer of choice. Please read this instruction booklet carefully before beginning installation and also take a moment to review the included limited warranty information. This instruction booklet is broken down into several categories for ease of use. Some of the topics may not apply to every application, but all of the information will be very beneficial during the cam installation process. For step-by-step visual detail, it is recommended to watch the COMP Cams® DVD “The Proper Procedure to Install and Degree a Camshaft” (Part #190DVD). If you have any questions or problems during the installation, please do not hesitate to contact the toll free CAM HELP® line at 1-800-999-0853, 7am to 8pm CST Monday through Friday, 9am to 4pm CST Saturday. Important: In order for your new COMP Cams® camshaft to be covered under any warranty, you must use the recommended COMP Cams® lifters and valve springs. Failure to install new COMP Cams® lifters and valve springs with your new cam can cause the lobes to wear excessively and cause engine failure. If you have any questions about this application, please contact our technical department immediately. Camshaft Installation Procedure 1. Prepare a clean work area and assemble the tools needed for the camshaft installation. It is suggested to use an automotive manual to help determine which items must be removed from the engine in order to expose the timing chain, lifters and camshaft. A good, complete automotive manual will save time and frustration during the installation.
    [Show full text]
  • M3 Engine Booklet
    Metric Mechanic’s M3 Engines M3/S14 Engine Specifications Copyright© June 2012 by Metric Mechanic Inc™ 505 East Main, Richland, MO 65556 Page 2 PH: 573-765-1269 FAX: 573-765-4216, metricmechanicinc@mac .com, www.metricmechanic.com Sport 2500 M3 Engine Metric Mechanic’s Sport 2500 HiFlo ST S14 M3 Engine General Engine Description Straight from the factory, BMW M3’s are great performance sedans! With their bigger brakes, better suspension and more powerful high rev engines, the M3 engine is strong, well built and reliable even though more aggressively driven. The average engine life expectancy is about 140,000 to 150,000 miles. But some owners feel the M3 lacks low to mid- range rpm “grunt”. In other words, it doesn’t pull to their liking below 4,500 rpms. Metric Mechan- ic’s “fix” is to enlarge the engine. We up the bore from 93.4 mm to 95 mm and increase the stock 84 mm stroke to 87 mm. Enlarging the intake ports from 26 mm to 29.5 mm, helps the engine breath. The net result is a bigger engine with improved low end and mid range torque, and expanded top end breathing - in other words - a 2.5 liter M3. Metric Mechanic 2500 HiFlo ST M3 Engine - 235 HP M3 Engine Anatomy Head Porting the 4 Valve M Head A 16.5% flow increase is achieved by machining the intake ports to 29.5 mm (26 mm stock). See “Metric Mechanic HiFlo ST M3 Head” chart on the next page. By using stock cams and porting, the engine ends up with a very flexible power band on the street.
    [Show full text]