Must be factory correct for the year, model, and horsepower claimed. Dealer-installed engines and dealer-performed engine modifications are not allowed. Casting numbers must be correct for the year and horsepower claimed including intake manifold, heads, and exhaust manifolds. Head modifications are prohibited, including, but not limited to, porting, bowl cutting, gasket matching, oversized valves, etc. Heads can be cut to help achieve the allowed compression over advertised. Blocks do not have to be "numbers matching," but they must be the correct displacement. Overbores up to .070" are allowed. Stock cranks only. NO strokers! Random P&G checks are possible. Lightweight cranks and connecting rods are NOT allowed. If found, you will be banned from the event until corrected! Aluminum rods are NOT allowed. Smaller-than-stock rod journals are NOT allowed. Aftermarket pistons are allowed, but piston rings can be no thinner than 1/16", 1/16", and 3/16" for top, second, and oil rings, respectively. Gas porting of pistons NOT allowed. Metric and pressure-back-type rings (dykes, head land, etc.) are NOT allowed. Torque straps allowed.

Compression Ratio Limits


All Engines – 1.5 extra points allowed over advertised. Contact us so we agree on the advertised compression.
Engines with factory dished pistons will be allowed to run either a smaller dish, a flat-top piston, or a small domed piston to achieve the maximum allowed compression.
Engines with factory flat-top pistons will be allowed to run a domed piston to achieve the maximum allowed compression.
Engines with factory domed pistons must run a dome of equal or greater dome volume than stock to achieve the maximum allowed compression ratio.
Heads can be milled and blocks decked within reasonable limits in combination with above to help achieve the maximum allowed compression ratio. 

Camshaft and Valvetrain

The camshaft must be correct for the year, model, and horsepower claimed for the type of lifter (hydraulic or solid). Roller cams NOT allowed. Duration at .050" lobe lift must be within 1% of factory specs. Lift at the valve must be within 2% of factory specs. Engines must be able to produce at least 16.0 inches of vacuum at 1200 rpm. However, some factory-produced engines were not able to generate 16.0 inches in showroom condition, so those cars will be given a variance to the rule. Solid-lifter cams lift checked at zero lash.


The valve train must be factory stock for the year, make, and horsepower claimed. Rocker arm ratio must be correct for the year and horsepower claimed. No aftermarket rocker arms of any kind allowed. Stock stamped steel or stock cast iron factory rocker arms only. Random requests for valve cover removal WILL happen. Poly-lock type adjustable nuts, jam (crimp) nuts, and adjustable pushrods are allowed. Valve covers must be correct for the year, make, and horsepower claimed. OEM-style replacement lifters only – no trick racing lifters (i.e. ceramic) or shimmed (limited travel) hydraulic lifters allowed. Maximum valve spring SEAT pressure allowed is 130 pounds. Higher seat pressure will require factory documentation. Factory spring configuration must be retained; that is, if your car came with single valve springs, you must run single springs. If it came with dual valve springs, you must run duals. Beehive valve springs are NOT allowed. No aluminum or titanium valve spring retainers allowed.


Ignition and Charging System

The ignition system must be stock, including the distributor, cap, coil, and wires. Points may be replaced with any electronic conversion that fits under the stock distributor cap. Replacement coils are allowed as long as they are the correct shape, color, and size. Coils must be mounted in the correct location with correct brackets for the make, year, and engine combination. We will no longer allow the use of aftermarket ignition boxes like MSD, Crane, Jacobs, etc. We made this decision based on participants using these ignition boxes for traction and total timing manipulation while making runs. You will be allowed to use a rev limiter, but the unit must be only a rev limiter and nothing else. Spark plug wires must be of correct appearance in size and color for the vehicle.


 The battery must be retained in the original location and securely fastened down with the original style hold down. The charging system must be fully operational at all times. The removal of the alternator belt is not allowed. Lightweight batteries are NOT allowed.

Pulleys: All pulleys must be factory issue and be correct diameters for the year and horsepower claimed for the engine. Belts running the water pump, alternator, and power steering must be retained at all times. Air conditioning belts may be removed if they do not affect other components. 

Manual Transmission

The transmission must be correct for year, make, model and engine of the car. 3-speed manuals may be upgraded to the correct 4-speed if originally available. Aftermarket H-pattern shifters are allowed if no modifications to the floorpan are necessary. Line locks are not allowed. Scattershields are okay. No conversions from column-shift to floor shift allowed unless available as a factory option. Aluminum flywheels are NOT allowed.

Automatic Transmissions

The transmission must be correct for the year, make, model, and horsepower claimed. Shift improver kits are allowed. Aftermarket shifters are not allowed. No manual valve bodies. Lightweight purpose-built, drag racing transmissions NOT allowed (for example Pro Trans, Kilgore, etc.). Just switching to aluminum drums is illegal. Anyone caught will be banned from the event until corrected! Torque converters must be within 1 inch of the stock outside diameter. Maximum stall limited to 2200 rpm. Higher stall speeds will require factory documentation.

Rear Axles

The rear axle must be of the same manufacturer as the car. Any gear ratio is allowed. Lightweight driveshafts NOT allowed.

Driveshaft safety loops are mandatory on all cars 13.99 and faster! Spools of any kind are NOT allowed.