Pushrod length, 1974 400 engine
 

The engine in our '67 LeMans is a 400 from a 1974 Pontiac. Recently, I had an issue with a rocker arm coming off the stud and the exhaust valve stayed closed. Scared the heck out of me when the engine started running like crap.
I noticed that the pushrod has some scarring now and I was thinking of just replacing them all. But I see two different dimensions: 7.794 and 9.136. I know that I can pull the valve cover and pull one out but I just wanted to see if anyone knows off the top of their head which one is correct.

9.145”

9.136”

Either one would be correct.

Pontiac V8s never used a pushrod that was 7.794”.

1966 and earlier (some 1967) used shorter 8.715” pushrods.

Alot of aftermarket offerings are rounded off at 9.150 they are just fine
Make sure they are hardened 5/16 dia and 5/16 ball or swedged / inserts tips on ends

Thanks, guys

If the 9.145" lenght is true then that's a better choice for a high milage motor with some rocker ware .

Would it be prudent to replace the rocker arms as well? It's not like it's a huge cost.

What is the casting number on your heads?
1967 heads w/guideplates 2:nd design) takes the 9.145" lenght pushrod and the longer rocker than the 1967 heads (1:st design) not using guideplates.