1970 NASCAR International Stock Car Racing Rule Book NASCAR Grand National Championship Circuit Section 20-15 -- Cylinder Head

a. Must be standard production. Internal changes permitted.

b. A cylinder head is considered to be a "Standard Production" head if:

(1) It is the required cylinder head for a previously approved complete engine, said engine being available as an optional engine for a regular factory product offering.

(2) It does not change combustion chamber, type of valve action (Push Rod) or number of valves, used in the cylinder head assembly of the approved engine.