meet the rules and not fall into the category of unfair competition. The Chevy Vortec and the Ford GT 40 are not allowed.
Cylinder heads must be from the same manufacturer as the engine block (except
Dart). Milling or angle milling of the cylinder head to any amount is allowed. No epoxy
or coating of heads is allowed. Heads
may be ported but no material may be added. Intakes may be port matched to
cylinder head only. Valve head sizes are optional providing they maintain stock
OEM positioning In valve guides (distance apart and angles). Valve guide liners
are allowed. Valve material must be one piece solid steel or stainless steel, no
titanium, or sodium filled valves allowed. The only titanium allowed in these
engines is the valve spring retainers. Any carbon fiber engine parts are illegal, Any amount of valve seats per cylinder head may be installed for
the purpose of repairing a head. Any angle valve job will be permitted as long
as it is done on a machine that cuts concentric to the valve guide center. Valve
stern maximum and minimum diameter, plus or minus .005" must be as follows:
Chevy 11/32, Ford 11/32", Chrysler 11/32". No hand grinding, sanding,
blending or de-burring where a cutter or stone leaves off.
OEM stock production or aftermarket solid steel rods are allowed. No titanium, aluminum, or billet. Rods may not be polished. Rod lengths must be OEM specs for the engine block used.
Any steel or cast iron crankshaft is allowed providing it maintains stock stroke as manufactured for the engine
block used. Aftermarket OEM replacement crankshafts with holes drilled through crankpins are allowed providing they maintain stock appearance and specs. No lightweight cranks. Minimum rod and main journal sizes must be either Chevy, Ford, or Chrysler specs only. Minimum rod journal is 2.100". Knife edging, narrowing, or cutting down the diameter of the crankshaft counter weights is not allowed. No polishing of the crank.
Any brand, three ring flat top aluminum pistons only, No coating of any kind are allowed.
Any steel or cast iron, stock OEM vibration dampener is permitted providing it is not machined or altered in any way. No fluid or friction dampeners.
Any make hydraulic or flat tappet allowed. No roller cams, roller gear driven cams, mushroom lifters or lash caps are allowed. Shaft rockers and stud girdles are not allowed. Engines with stock OEM shaft rockers are legal. Roller rockers with optional ratios are legal. Lifters must maintain stock OEM diameters. Lifter bores must remain in stock OEM positions and angles, but may be re-bushed for wear. A flat steel lifter galley plate may be used to prevent engine damage in case of push rod failure.
May use a stock passenger car, cast iron 2 barrel Intake. An optional aluminum four barrel as cast box stock, spec manifold may be used. No work of any kind may be done on this optional manifold. No porting, polishing, welding, or acid dipping. Intakes may be port matched to cylinder head only. May use Chevy SP1, Ford 2980 or 2981, Chrys 2920
Any American Stock OEM 2 barrel carb. up to 1 1 1/16" throttle bore with no adaptor plate is legal on cast iron manifolds. The Holley carb. 4412 is acceptable and must run a maximum spacer adapter of 1 1/16 including gaskets. No modifications of any kind will be allowed to these carbs. except those listed below. Conventional round type air cleaners only, Air cleaners that provide ventilation through the top cover such as K&N are permitted. No air induction plastic carburetor inserts or other devices to direct air into intake, No air diffusers are allowed. CARBURETOR MODIFICATIONS ALLOWED ARE LISTED BELOW, ANY OTHER MODIFICATION NOT MENTIONED ARE NOT LEGAL.
Holes drilled in the throttle plates for proper idling
Drilling, tapping and plugging of unused vacuum ports.
Welding of throttle shaft to linkage arm
Drilling of idle or high speed air correction jets
Milling of center carburetor body metering block surface a maximum of .015" on each side.
Removal of choke plate and shaft
The jets may be changed as needed
Stock OEM Distributors and coils only. No trigger ignition systems allowed. No Mallory or Accel ignitions may be