Breaking rocker arm studs

66canbuilt · Veteran Member

Breaking rocker arm studs

66 Beau · Poncho Master!

How much cam are you running? Any chance you've got springs binding? Have you checked to make sure your springs will compress enough to suit cam & lifter ratio?
If you ran old springs, did you add spacers under them to get spring load back up to par? These will increase spring pressure but they reduce spring compressed height.

66canbuilt · Veteran Member

2drpost wrote:
whose rocker studs? GM, aftermarket?

aftermarket - Pioneer Automotive

66canbuilt · Veteran Member

not sure

-it gets worse -- I noticed the push rod on that rocker is sitting lower than the rest of them. When the engine is cranked over -that push rod does not move. It is not bent and seems to be sitting in the lifter???

66 Beau · Poncho Master!

Hmm. Sounds like the cam lobe is wiped? Are these hydraulic lifters? Are you running really high RPM's? How long has the engine run since rebuild? DO you have engine/head/cam specs? h

66canbuilt · Veteran Member

they are hydraulic lifters , never rev it high (over 3500 to 4000) not sure how long ago the engine was rebuilt - not more than 10,000 miles , it a 350 stroked to 383 with 1966 camel hump heads 3782461 , comp cams 12-242-2.

I thought about the cam lope - but why would that break the rocker stud?

66 Beau · Poncho Master!

A wiped out cam lobe and a broken rocker arm... hmmm.

Maybe the rocker was jamming - not pivoting so there was a lot of resistance on the push rod (high load on the cam - and the rocker shaft). Is there any sign or indication rocker was not 'rocking'? Are they stock rockers? If they're used, did you mix and match, or keep the same rocker & rocker ball together?

Is there wear on the valve side of the rocker?

66canbuilt · Veteran Member

It looks like a broken lifter,that somehow pushed up and broke the rocker stud.

Will know for sure when the intake comes off

66 Beau · Poncho Master!

To got my curiosity piqued now. Let me know what you Fong.

66canbuilt · Veteran Member

Car is in my friends shop now.

It is now looking like bad rocker studs. Can't find any strange wear on anything,it all looks good.

As he was taking the rockers off the other side of the engine from where the studs broke(to replace with 7/16 studs i bought) another old stud broke in his hand!