1967 NASCAR International Stock Car Racing Rule Book NASCAR Grand National Championship Circuit Section 20-12 -- Engine

a. See Rule 1-a.

b. Numerals indicating the cubic inch displacement of engine must be painted on both sides of hood in numerals at least eight inches high.

c. Internal polishing, porting, altering and/or relieving of motor parts permitted.

d. Oversized oil pans and oil coolers are not to be used unless approved by NASCAR. Oil pans must have a minimum ground clearance of five inches.