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
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If the 9.145" lenght is true then that's a better choice for a high milage motor with some rocker ware .
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Would it be prudent to replace the rocker arms as well? It's not like it's a huge cost.
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Quote:
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. |
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