Is it common to break stock rocker shafts?

Well, just last night i broke my 2nd stock rocker shaft since ive had the car (July 3rd). The first time happened about a month and a half ago. The shaft broke in front of the front driver's side shaft bolt, inbetween the first and second rocker.

Last night, it broke on the passenger side. It split right in at the middle mounting bolt. The rear passenger bolt snapped in half and the whole rear half of the rocker shaft lifted up touching the top of the valve cover.... needless to say i killed the ignition right away when i heard it!!! :eek:

Is this a common occurance with stock shafts? It is getting really really annoying. Is it possible that my camshaft profile is a little too aggressive for the stock valvetrain? I have a flat tappet 218/218.

What what you guys suggest be a remedy for this? I already have a set of RJC rocker braces that i just installed. But is that really going to prevent this from happening again? Should i just bite the bullet and get a set of roller rockers? Or should i just go with TA rocker shafts?
 
never had a problem when i installed my rjc braces. but if you cant afford roller rockers just get heavy duty shafts. i have a set of stock shafts if you need them.
 
i broke one on my 455 but havent had a problem with the ones on my gn. ive heard of the stock ones breaking a few times before so id say that its kinda common.

buickbert
 
I had a stock one break.

I bought new ones from NAPA to replace both sides and they were made of heavier metal than the stock shafts.

That was in 1998 and if i remember correctly they cost $38.00 for the pair.


John :smile:
 
i ran the stockers for 10000miles(and a few passes at the track), with 125lb. spring pressure and a 206 roller cam, no failures here. ive since installed my solid shafts with new buttons and rockers. about 90 dollars for the shafts and buttons, dont remember rockers cost but it wasnt much. hth!
 
If you go with rollers you will need to notch the pedestals if they are not already notched to clear the rockers.
Cheaper and easier to go with heavy duty rocker shafts, bolt on and go.
I broke the stock shafts also, exact same place as you are describing.
I ran the HD shafts until I went to Champion heads, they were already cut to clear rollers.
HTH
 
Well, just last night i broke my 2nd stock rocker shaft since ive had the car (July 3rd). The first time happened about a month and a half ago. The shaft broke in front of the front driver's side shaft bolt, inbetween the first and second rocker.

Last night, it broke on the passenger side. It split right in at the middle mounting bolt. The rear passenger bolt snapped in half and the whole rear half of the rocker shaft lifted up touching the top of the valve cover.... needless to say i killed the ignition right away when i heard it!!! :eek:

Is this a common occurance with stock shafts? It is getting really really annoying. Is it possible that my camshaft profile is a little too aggressive for the stock valvetrain? I have a flat tappet 218/218.

What what you guys suggest be a remedy for this? I already have a set of RJC rocker braces that i just installed. But is that really going to prevent this from happening again? Should i just bite the bullet and get a set of roller rockers? Or should i just go with TA rocker shafts?

What valve springs are you using?
 
been there...

I broke a stock shaft on my previous '87 GN. The head of the pass. side rear shaft bolt just popped off and the shaft snapped in-two right at the middle bolt.

I was about half-way through a back-road drag race when that rocker shaft snapped - WOW!!! what a noise that was!! :eek: At first I thought I had thrown a rod! :p ScanMaster showed 33 degrees of KR!!! :eek: :eek:

replaced the stock shafts with a pair of HD's from Postons and never had any more problems with the rocker shafts. At the time, I did not install the RJC rocker-shaft braces, but after looking at the way that shaft bolt failed, I'm positive the RJC braces would have prevented it. I haven't ordered a set my current GN, but I probably will soon.

Rob
 
My experience has been that if you add a cam with much more than stock lift, you will break the stock shafts. Seems to be commom. If your not ready for roller rockers, find someone with solid shafts.
Broke several stock shafts and then added solid rocker arm shafts. Problem solved. This was many years ago so I don't know who sells solid shafts today.
 
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