1970 NASCAR International Stock Car Racing Rule Book NASCAR Grand National Championship Circuit Section 20-1 -- Competing Models

America's greatest auto race drivers competing with the finest equipment developed by America's automotive manufacturers.

a. NASCAR Grand National races are open to steel bodied 1968, 1969, 1970 models of American-made passenger car production sedans, available to the general public, classified as follows: Standard and Intermediate.

The specifications for the Grand National Division, in essentially the same form as listed here, have been accepted by the Automobile Competition Club of the United States -- FIA and by the FIA for inclusion in the Appendix J. They will be listed in Category 5B of the special touring sedan section.

Category 1--Standard size cars.

Limited to cars with a minimum of 119-inch wheelbase, a maximum engine size of 430 cubic inches piston displacement, standard body size and complying with minimum weight requirement as set forth in paragraph 1b. (OVERBORING: A total maximum of one cubic inch will be permitted for overboring because of cylinder wear).

The following 1970 cars have been classified in Category 1 --

The following 1969 cars have been classified in Category 1 --

The following 1968 cars have been classified in Category 1--

Category 2--Intermediate size cars.

Limited to cars with a minimum of 115-inch wheelbase, and less than 119-inch wheelbase, a maximum engine size of 430 cubic inches piston displacement, standard body size and complying with minimum weight requirement as set forth in paragraph 1b. (OVERBORING: A total maximum of one cubic inch will be permitted for overboring because of cylinder wear.)

The following 1970 cars have been classified in Category 2 --

The following 1969 cars have been classified in Category 2 --

The following 1968 cars have been classified in Category 2--

Category 3--Compact or GA Cars. (Not eligible in this division)

Limited to cars with a wheelbase of less than 115 inches, with a maximum engine size of 335 cubic inches piston displacement.

Category 4--Sports cars. (Not eligible in this division)

Category 5--Grand American cars. (Not eligible in this division)

b. Minimum weight Category 1 and Category 2 cars. 3900 pounds for all cars, with gas, oil and water, ready for racing without driver.

c. Eligibility.

(1) It is mandatory that a street version engine be produced by the manufacturer as a regular production option for installation and sale to the public in a regular product offering. For 1970 the eligibility quantity for bodies will be 1000 minimum or a figure equal to one-half the number of franchised dealers, whichever is the higher. Engine production requirements will continue to be 500 engines installed in cars before approval to compete is granted.

(2) Production models and production engines introduced by January 15, 1970, will be classified eligible for competition in 1970. New models or engines introduced after January 15, 1970, will not be eligible for competition until April 15, 1970. Any equipment introduced after April 15 will not be eligible during 1970.

The following characteristics must be identical with the production engine upon which recognition of type has been granted:

CYLINDER BLOCK
Material
Number of Cylinders
Angle of Cylinders
Number of Main Bearings
Integral or seperate Cylinder Sleeves
Location of Camshaft
Overall Configuration

CYLINDER HEAD
Material
Number of Valves per Cylinder
Type of Combustion Chamber
Location of Spark Plug
Orientation of Spark Plug
Arrangement of Valves
Type of Valve Actuation
Number of Intake Ports
Number of Exhaust Ports
Center Distances of Intake Ports
Center Distances of Exhaust Ports
Shape of In & Ex Ports at mating faces of manifolds
Angle of Port Face relative to mating face of Head to Block

GENERAL
All parts must originate from stock production castings and forgings which have been machined according to the normal machining schedule utilized for standard production parts. They may be subsequently refined, modified and improved by further machining or rework.

(3) The ACCUS car classification committee will determine if the eligibility requirements have been met.

(4) All eligible engines can be used in the standard size (Category 1) or the intermediate size (Category 2) cars.

(5) There will be no weight or displacement handicap on any car or engine in 1970.

(6) Maximum engine displacement for Category 1 and Category 2 cars is 430 cubic inches, with a total maximum of one cubic inch permitted for overboring because of cylinder wear.

(7) All model, engine or equipment changes or modifications not governed by NASCAR rules Section 20 c (1), (2) and (3) must be submitted for consideration of approval, not less than 30 days prior to the date of intended usage in NASCAR competition. The applicant will be notified of approval or rejection no less than 15 days before the date of intended use. Any equipment which does not conform to specifications or tolerances contained in the NASCAR Rule Book, will not be eligible for approval during 1970.

No changes from standard production automobiles or component parts will be permitted except as specified in following specifications: