O.K. Everyone quit whining!
The following rules were a mere idea from over three years ago!
The rules are getting shaped and changed every day. The technology advisor was on the phone yesterday with every cylinder head manufacturer known to man to do as much homework on the approved heads as possible, make the parts as reasonable as possible, and make sure the approved heads will be in great supply for the next five years. The rules are in good hands. However, they will be finalized and listed here in just over a month. Check back for the complete rules, and until then, don't get an ulcer over what is listed here. And don't buy parts until you see the final rules.
GM/Chevrolet OEM passenger car or truck, cast iron, and commercially available block. 4.000 minimum bore, 4.060 maximum bore. 2 and 4 bolt mains permitted. No aftermarket blocks. No splayed main caps. No bushed lifter bores. Lifter bores must remain in OEM location and within .005” of stock. No keyway lifters. Maximum deck height 9.030 Minimum deck height 8.990”. Centerline of bores and corresponding deck surfaces must remain at a 90 degree angle to each other, and bore spacing to remain at factory OEM specs . Block spacers prohibited.Wet sump oil system mandatory. Oil pump of stock style and stock location mandatory. Gerotor pumps prohibited. Any steel oil pan with maximum capacity of 14 quarts. External oil pumps prohibited. Vacuum pumps prohibited. Pan-u-vac systems permitted. Aftermarket or external oil drain-back systems are prohibited. Oil accumulators are prohibited.
3.48 - 3.500 stroke OEM or equivalent crankshaft in all aspects. Minimum crankshaft weight 50 pounds. Main and rod journals must remain OEM width and within .031 of stock diameter. Up to .125” chamfer bearing surfaces permitted. Coating, profiling, shaping and or knife edging of counterweights prohibited.
OEM or equivalent steel connecting rods in all aspects. H beams permitted.
One of two choices exists:
5.70 length center to center. 565gram minimum. Bushed pin ends permitted. –or-
6.00 length center to center. 600gram minimum. Bushed pin ends permitted.
Stock style cast, forged or hypereutectic, flat top pistons with minimum of 2 valve relief. 435 grams minimum weight. Engine must yield no more than 10.0:1 compression, zero tolerance.. Pistons must have a 1.550-1.560 compression height for 5.7 rod, and a 1.250-1.260 compression height for a 6.0” rod. Mandatory .927 diameter wrist pin, and a STANDARD, three ring, 1/16, 1/16, 3/16 ring package. Piston coating permitted. Gas porting of any kind or style is prohibited.
Wrist pins must be .927 diameter (+ or - .003) and must weigh a minimum of 105 grams. Wrist pins may be coated.
Speed-Pro, Child's & Albert or Akerly & Child's; plasma moly racing ring set, series number 9771. No out of the box modifications other than file fit. (Entire ring package minimum weight 52grams.)
Any standard automotive type head gasket permitted. Minimum thickness .026” and maximum .052”
Any timing chain set or Pete Jackson style gear drives permitted. Any other system, including but not limited to variable cam timing devices, nylon gear sets, or belt drives prohibited.
Stock type cam, rod and main bearings mandatory. No roller cam, rod or main bearings. Bearings must be composed of traditional bearing materials. Bearing coatings permitted.
Any engine or thermal coatings other than the listed piston, bearing, wrist pin and header coatings prohibited.
Hydraulic flat tappet camshafts with .510" lift maximum at the valve, and 245 degrees of duration at .050. Hydraulic cam followers/lifters mandatory. No mushroom lifters, and no lifter may have more than .010" convex shaping. No passages of oil delivery to the cam lobe will be accepted. No out of the box modifications may be made to the camshaft or lifters.
Any stock style points distributor or HEI distributor permitted. Any computer, or electronically maintained ignition system prohibited. Magneto ignitions prohibited.
Any OEM Chevrolet stock iron cylinder head meeting listed requirements. Aftermarket cast iron heads as follows: Dart Iron Eagle, World Products S/R Torquer , Pro Topline/ Pro Torquer cylinder heads and EQ Lightning heads, with the following criteria. 23 degree heads. No porting, No polishing. No bowl Blending. No abrasive cleaning. No port or gasket matching. No grinding or angle milling. All valve angles must remain within 1degree of “as cast” specifications.
Maximum 180 cc intake runner castings will be accepted
Maximum intake valve size: 2.02 (Standard 11/32 stem mandatory. Minimum weight TBD)
Maximum exhaust valve size: 1.60 (Standard 11/32 stem mandatory. Minimum weight TBD)
Any aftermarket valve seat prohibited Standard cast iron or ductile iron seat mandatory. Undercut valves prohibited. Maximum undercut on swirl polish .010". Maximum of 3 angle valve job permitted. (Valve job specs TBD.)
Closed maximum spring pressure: 130 lbs (Max installed height 1.910, Minimum installed height 1.650.)
Standard ‘single dimension wire’ wound valve springs mandatory. No Beehive style, helical or elliptical type springs.
Minimum chamber volume: 62.0cc
Maximum chamber volume: 73.0cc
10.0:1 maximum static compression.
Spark plugs and spark plug wires must be commercially available, and their design must remain unmodified.
Any steel push rod. 5/16 or 3/8 diameter accepted
Valves, valve springs, keepers and retainers shall be steel.
Stud mounted roller rocker arms permitted. 1.520 ratio maximum. Posi locks permitted. No shaft style rocker systems. Stud girdles permitted.
Intake manifold options. Edelbrock performer # 7101 Wieand stealth #8016, Holley #300-36 or Professional Products #52021 or #52020. No machining, porting, abrasive cleaning or modifications of any kind to the inside or underside of the intake manifold will be allowed.
Holley Carburetors part number 4777 or Demon Carburetors part number 1282010. No out of the box modifications other than floats, needle and seats, jets, power valves, squirters, and manufacturer designed air bleeds. Max.venturi size is primary 1.250",secondary 1 5/16" max.base plate size is 1 11/16"
1” carb spacer maximum. Velocity stacks preferred. Any scoop or flame arrestor must aim directly to the transom of the boat. (More directions on scoops to come)
Fuel must be delivered to the carb by one single mechanical fuel pump only.
Exhaust system, maximum 2” primaries and maximum 3.5” collector. Standard 4 into 1 collectors mandatory, unless running zoomie headers. Step headers, merge collectors and multi diameter collectors prohibited. Exhaust spacers prohibited.
Engines will run on a standard 92 octane pump gas with no additives allowed. More rules to come in the realm of acceptable and possibly spec fuels.Any power adder, consisting of, but not limited to; Superchargers, Nitrous oxide injection, turbochargers, water injection, or oxygen injection is prohibited
No titanium, beryllium or scandium internal engine parts.
Check back for the final rules