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Old 10-07-2021, 10:47 AM
66sprint6 66sprint6 is offline
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Default 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.

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Old 10-07-2021, 10:53 AM
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b-man b-man is offline
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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.

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Old 10-07-2021, 11:07 AM
Formulas Formulas is offline
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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

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Old 10-07-2021, 11:14 AM
66sprint6 66sprint6 is offline
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Thanks, guys

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Old 10-07-2021, 11:30 AM
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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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Old 10-07-2021, 11:48 AM
66sprint6 66sprint6 is offline
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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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Old 10-07-2021, 02:29 PM
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Quote:
Originally Posted by 66sprint6 View Post
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.
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.

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