NATIONAL RACEWAY/ THUNDERHILL RACEWAY
-Any 1960 or newer full size car with 101” minimum wheel
-All glass must be removed and a minimum of three, 3/8” diameter steel rods, added to the
windshield area in front of the driver
-All upholstery, headlights, tail lights, mirrors, chrome
and all flammable materials must be removed
-Minimum cutting for the tire clearance is allowed
-A track approved roll cage with padded roll bars in
driver area is required. Roll cage must
be welded to frame. All doors must be welded or bolted shut.
-Racing seat, harness and window net is required and must
be used anytime in car is on the track
OEM CAST IRON:
-compression not to exceed 175 lbs
-362 cubic inch MAX.
-Max cylinder bore allowed is 4.060”
-No stroking or destroking allowed. Stroke must be GM
3.480”, FORD 3.500”
-Stock 5.7 factory production rod
-Pistons dished or flat top 2 OR 4 valve relief pistons
-Pistons must stay flush with or below top of block
-Factory passenger production heads only, no dart, no bow
tie, or aluminum heads allowed
-No angel plugs or performance heads allowed
-Max valve 1.94
-Poly locks permitted
-No polishing, porting or match porting anywhere
-No milling inside chambers, each chamber must have a
55cc minimum volume
-Stock ratio rockers with stock diameter pushrods(roller
-Headers or manifold allowed . No 180 degree headers.
-Hydraulic cam and lifters only. No roller cams.
-Balancing of engine is permitted
-Screw in studs or pinned studs allowed, guide plates
-Factory forged cast-iron or steel crankshaft with OEM
factory casting numbers.
-No knifing. 50 lb. minimum weight.
-Stock style distributor, may hook a RPM limiter, NO MAGS
or MSD BOXES.
-Engine set back no further than No. 1 plug in line with
-Must run gasoline. No alcohol.
-Any intake NO HIGHRISERS.
-2 barrel *500 CFM. Must pass track inspection. (Measured
with go/no-go gauge). Or factory 4 barrel
-The bottom of the carburetor throttle bore maximum can
be no larger than (1 11/16) inch diameter.
-With max stock venture (1 3/8) inch.
-Max 1 inch adapter plate OR space under carburetor
-Removal of choke plate and or tower allowed.
-Manual fuel pumps only.
-All suspension must remain in stock location.
-Racing springs and shocks allowed. Spring buckets and
lowering blocks allowed. No weight jacks.
-Rear end may be locked.
-A 9 inch Ford rear end allowed. After market axles are
-Floaters are allowed.
-Drive shafts steel only – painted white with strap.
-4 wheel working brakes and after market components ok.
-Rear disc brakes ok, rotors and hats must be steel.
-No wedge blocks. No adjustable bars. No weight jacks.
-No traction control devices.
-Stock/OEM Manual or automatic with working torque
-Minimum 10.5 inch
-Flywheel must be steel and weigh a minimum of 20 lbs.
-No aftermarket transmissions.
-275/60 D.O.T. tires, Hoosier 500 (36103, 36105, 36107)
IMCA G 60-15 or American Racer KK704.
-8” steel wheels max.
-Bead lock allowed on right rear and front.
-REAR tires must punch – 50 anytime.
-Softening is not allowed. Solvents of any kind are not
allowed. Altering tires with any components or chemicals which after the manufacturers
baseline-settings of the tire is not allowed.
-Grooving and/or siping is permitted.
-All sidewall markings must remain visible at all times.
Buffing or removing of the compound designations is not allowed.
HAS FINAL SAY IN ANY SITUATION.