I've been a avid CC reader for awhile and decided it was about time i joined the forums.
Anyways, There is a local Imca track about a mile from my house and from time to time i build engines for the local Hobby stock class racers... Most of the racers i get want a good engine that will rev fairly fast but without sacrificing Hp or Tq... which is why i normally base my build off of a chevy 350 block.
Anyways, A guy i know has recently requested that i build him a engine that will rev a LOT faster than anyone else on the track, even if it means costing him Hp and Tq.
Normally i would go straight for 400 block and destroke it to 377 with a 350 crank as this is one of my favorite setups for stock car class, but in the hobby stock class the imca has a 361 cubic inch limit.
So, My next thought is of something i haven't built before but have heard of people building it and having good success.... My thoughts were to take a 400 block and destroke it with a 327 crank, this should put me at about 347 cubic inches which is under the limit and the engine should really rev, But my thoughts wonder how much power will even be behind all those Rpm's with such a short stroke???
Any opinions on this would be greatly appreciated, especially to any of you out there that have built this setup and ran it on a oval dirt track.
The crank has nothing to do with RPM if you have rules to go by. Now the rules allow for a replacement crank. Most replacement cranks are 3.5 and not 3.48 making a .030 350 into a 357, why would you want to give up 5 cubic inch by building an illegal smaller 352 in a cut throat rule book racing. Your best bet is to run H-11 stock diam springs and sleave the guides down to run 5/16 valves, with titanium retainers. 5/16 valves are not as strong as 11/32 valves, if you float a valve, 11/32 bend and 5/16 break. Run 6" rods cause that will make the piston lighter, and have the pistons lighten on top of that. Run a 2 ring mm set up and not a 3 ring set up with a total seal top ring. Nothing in rules say you can't do this, but it is all interpretation of the rules so this still may not be allowed so you would have to check with the rule makers. None of this is cheap and is high maintenance and you will be screwed when it gets claimed, and it will get claimed once it starts to win.
24. ENGINE SPECIFICATIONS: Any American make engine allowed. BLOCK: OEM steel passenger vehicle production block only. No GM Bowtie, Ford SVO or Chrysler W components allowed. GM approved block numbers are: 3892657, 3914660, 3914678, 3932388, 3932386, 3956618, 3970000, 3970006, 3970010, 3970014, 10066033, 10066036, 10243880, 14010207, 14010209, 14010287, 14016376, 14016379, 10054727, 14088528, 14088548, 14088552, 14093638, 14101148. Stroke must match block. No 400 or larger cubic inch parts allowed. Maximum 361 cubic inches (GM); 363 (Ford); 370 (Chrysler). Violation of cubic inch limit must be verified by removal of head and will result in disqualification, loss of all IMCA points for the season, $1,000 fine and a 30-day suspension. Maximum compression ratio is 9.0 to 1, no tolerance. Compression ratio checked using Whistler and cubic inches checked using pump, OR by visual inspection of part and/or casting numbers, pistons, etc (track option which method is used). Flat top or dish pistons only, no gas ported pistons. OEM or OEM replacement steel crankshaft only – cannot be lightened (no aerowing, bullnose, knife edge or undercut allowed. Effective January 1, 2011, no drilling of second or third rod throws). OEM or OEM replacement steel rods only – GM 5.7 or 6-inch rod allowed. Cap screws allowed. Conventional flat tappet cam/lifters only, cannot alter lifter bores. OEM firing order cannot be changed (GM: 1-8-4-3-6-5-7-2). May use oil restrictors. ‘Wet’ sump oiling system only. Steel oil pans only. Racing oil pans allowed. Mandatory one inch inspection hole in all pans - no obstructions to crank and rods. Accumulator allowed, must be mounted under hood. CYLINDER HEADS: Steel only. Must be unaltered approved OEM and minimum 76 cc combustion chamber. Only GM OEM approved head numbers are: 14079267, 3986336, 3986339, 3986339X, 3986388, 3932441, 376445, 3928454, 3932454, 3876487, 3973487, 3973487X, 3973493, 3951598, 468642, 330862, 333882, 3998920, 3998991, 3998993, 3998997, 3970126. Maximum size valves on these heads are 2.02 inch intake and 1.60 inch exhaust. May use Engine Quest (EQ) Stock Replacement (SR) cylinder head, part number CH350I, head must remain as produced, seat angles and valve sizes can not be changed: three angle valve job only (absolutely no casting removal in valve pocket of EQ head, for any reason); Ford - no after market or SVO heads; Chrysler - no after market or W-2 heads, 360 cubic inch heads only. No porting, polishing or alterations of any kind to heads or intake, disqualification and $250 fine if illegal. OEM non-roller rocker arms only. GM - 1.250 inch maximum O.D. valve spring, no beehive valve springs allowed. Guide plates and screw-in shouldered studs (0.375 inch max) allowed. No stud girdles. Poly locks allowed. INTAKE: Must use unaltered OEM cast iron two barrel intake. No hi-rise or marine intake manifolds. Unaltered OEM type harmonic balancer only. OEM type steel or aluminum water pumps only.
25. ENGINE CLAIM: Refer to IMCA Operations and Inspection Manual or General Rules for claim eligibility requirements.
(A) $550 cash claim on engine, $25 goes to wrecker for pulling engine and $25 goes to official.
(B) Claim does not include - 1. flywheel, 2. clutch, 3. pressure plate, 4. bellhousing, 5. breathers, 6. carburetor, 7. starter, 8. motor mounts, 9. oil/temp. sending units, 10. fan and pulleys, 11. clutch ball, 12. clutch arm, 13. throw out bearing, 14. dip stick, 15. water pump, 16. fuel pump, rod and plate, 17. distributor, 18. plug wires, 19. water outlet and restrictor. 20. exhaust manifold and pipes.
NOTE: During engine claim, block and head numbers should be verified, intake should be visually inspected, exhaust manifold must be removed to inspect heads, and one spark plug must be removed to check flat top or dish pistons prior to transfer of engine to claiming driver. If, at this time, engine is found illegal, claimed driver is disqualified and suspended from all IMCA sanctioned events until such time as a $250 fine is paid, for first offense, second offense penalties will be $500 fine and/or suspension. Claimer then has option to accept or decline engine - if declined, driver is not charged with claim.
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