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50 Years of Pro Stock salute: A look back at the 1970 NHRA Pro Stock rules

Pro Stock cars have come a long way since their debut at the 1970 Winternationals. Here's a look at the very first Pro Stock rules, as printed in the 1970 NHRA Rulebook.
06 Feb 2020
Posted by NHRA.com staff
Feature
Pro Stock

The history of the Pro Stock class is being celebrated by NHRA in 2020 with a 50 Years of Pro Stock salute. The cars have come a long way since their debut at the 1970 Winternationals. Here's a look at the very first Pro Stock rules, as printed in the 1970 NHRA Rulebook.

PRO STOCK ELIMINATOR
Reserved for American built cars with American automobile engines with a wheelbase of 97 inches or more. Body engine, drive train, chassis, etc., may not be altered, modified or relocated, except as outlined in Class Requirements. Push starts not permitted. One class of competition for non-supercharged cars. Class is determined by total car weight divided by total cubic inches engine displacement with a minimum of 2,700 pounds. 

DESIGNATION
P, preceded by car number.
Class P – 7.00 or more lbs. per cubic inch.

CLASS REQUIREMENTS
Cars competing in Pro Stock Eliminator must observe the same requirements as Modified Production cars with the following exceptions.

BALLAST
Permitted. Maximum of 100 lbs. 

BODY
Must be 1968 or later model/year American factory-produced passenger car. The use of fiberglass or other lightweight components is restricted to hood, front fenders, splash pans, and rear deck lid, however, they must be exact duplicates of stock components replaced. Lift-off hoods and deck lid permitted. Any under hood modification, other than firewall alteration necessary for engine installation, will be allowed. Roll bars mandatory; roll cages optional. Sports Cars, Sedan Deliveries and Trucks not permitted in this class. Acid dipped bodies or body parts are not permitted. Original steel body shell must be retained. 

BRAKES
Four-wheel brakes mandatory

ENGINES
Engine must be of 1965 or later manufacture and must be same make as car. Any internal modifications permitted. Carburetion is limited to two 4-bbl. Or four 2-bbl. American automotive carburetors with any internal modification. 

EXHAUST SYSTEM
Open exhaust with headers permitted. Tailpipes and or mufflers optional. Outlets for open exhausts cannot exceed 4 inches in diameter. 

HOOD SCOOP
Permitted however hood scoops other than ones produced as factory equipment for the specific model and year of car may not extend more than 7 inches above the height of the original hood’s surface, as measured from the base of the hood scoop. 

REAR END 
Any rear end acceptable.

STREET EQUIPMENT
Any street equipment which does not affect the external appearance of the car may be removed, except head and tail lights and fan. 

SUSPENSION
Stock front suspension for the car body used must be retained.

TIRES
Slicks permitted. Rear tire tread may not exceed two inches outside the rear fenders and rear fenders must retain the original contours.

TRANSMISSION
Any stock-type transmission acceptable. Transmission must remain in conventional location, determined by engine used.

UPHOLSTERY
Full interior trim must be retained equivalent to factory specifications. Bucket seats may replace stock seats (two required) only if they are fully upholstered and full size American automotive seats. Dashboard exterior appearance must be retained. 

WEIGHT
Weighing required of all cars to determine classification. Maximum allowable weight on rear wheels is 55 percent of total car weight.

WHEELBASE
All cars must retain stock wheelbase, length and tread width for car body used. Minimum wheelbase length 97 inches. 

WINDSHIELD/WINDOWS
Full safety glass required. No plexiglass or other lightweight components. All windshields and windows must be clear, except for factory tinted safety glass. Product identification decals not permitted on any front door window or windshield. Windows must be closed; windows need not be operative. 

CLICK HERE TO VIEW THE 2020 RULEBOOK E-BOOK | PDF VERSION

For those desiring a hard copy of the Rulebook in the familiar pocket-friendly size, you can purchase one at the wallet-friendly price of $10. Click here to order. NHRA Members, call 1-800-308-6472 to receive a 30 percent discount. For a bulk-order form (10 or more copies), contact NHRA Membership Services: [email protected].