Rocker Arm Studs

[dan lephart]

I know this is not a Buick question but... My Dad just had his Pontiac 400 engine redone in his '70 Grand Prix. (I restored the under hood for him). Less than 200 miles a rocker arm stud broke. It was replaced. Less than 200 miles more and different stud broke. They replaced it. Another one broke 150 miles later. Any ideas what might be going on? The engine builder tells him "weak studs, I will replace all of them for you". He reused the original studs when he did the engine.
I have been arround the Buicks for thirteen years and I have never heard of this problem with our motors.
Any input you have will be appreciated. Thanks in advance.

 

[dan lephart]

ttt

ttt

 

[turbo nasty]

Are they screw in or press in studs?

Where are they breaking off at?

Is he getting coil bind?

Was the guides cut down for the bigger camshaft profile (if he has it)?

Does he have to large a ratio rocker arm?

Sounds like something is binding a peak lift. Ie- some of the above mentioned items?

Now if they are the original studs and the builder has went back with a bit more than stock cam set up w/higher spring psi's and left the original studs in, Makes me wonder on this persons capability.

 

[dan lephart]

short slot

Thank You for your responses! Sure enough the builder cracked the valve covers off and told my Dad "...there is scoring on all the rockers. This is because the rocker slot is too short." Prior to that his associate had come to the home to replace the broken studs. He has ordered new rockers. Now the next question. Has any damage been done? What to look for? I must add that when the rocker studs broke my Dad was very close to home and not going over 30mph. He crawled the car home.

 

[86bluet]

broke studs

Are you using roller rockers? if so did the machine shop slot the pushrod hole to allow for the extra lift. On a 389 we did not do that and bent half the pushrods be fore we figured it out