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.