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Old 11-17-2010, 05:56 PM
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Circle track engine options, need some insight!!

*long post ahead....beware*

Ok, IMCA stock rules changed this year, and I'm wondering about a few things. There are two different options we can go after, and I'm stuck on what I need to do.

Here are the two options...

(A) 350 cfm CARBURETOR ENGINE: No cubic inch or compression limit. Flat tappet cam/lifters and stud-mounted rocker arms only. No shaft or pedestal rocker arms. No titanium engine components. No stud girdles. No mushroom lifters, lifter diameter and configuration must match OEM passenger block. Full roller rocker arms allowed.

(B) 500 cfm CARBURETOR ENGINE: Maximum 361 cubic inches (GM); 363 (Ford); 370 (Chrysler). 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. 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. No compression limit. Flat top or dished pistons only, no gas-ported pistons. OEM or OEM replacement steel crankshaft only cannot be lightened. No aerowing, bullnose, knife edge, undercut or drilling of second or third rod throws. OEM or OEM replacement steel rods only GM 5.7 or 6-inch rod allowed. Cap screw allowed. Conventional flat tappet cam and lifters only, cannot alter lifter bores. Mandatory one inch inspection hole in all pans no obstructions to crank and rods. 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). No porting, polishing or unapproved alterations allowed to ANY cylinder head. Guide plates, screw-in shouldered studs (0.375-inch max) and polylocks allowed. No stud girdles. Full roller rocker arms allowed. GM 1.250 inch maximum O.D. valve springs, no beehive valve springs allowed. Unaltered OEM type harmonic balancer only.

The first HAS to use a 350 cfm 2 barrel, and the second can use a 500 cfm 2 barrel.

What option would make more power/torque? Any help or questions apreciated!
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