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1985 gmc 1/2 ton rocker arm studs
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lowboy99
New User
Jan 20, 2013, 4:43 PM
Post #1 of 8
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1985 gmc 1/2 ton rocker arm studs
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i have a 1985 gmc sierra with a 350 2 bolt main has mild rv cam my problem is motor has less than 500 miles on rebuild and it keeps pulling the rocker arm studs and breaking push rods. i have tied drilling the rocker arm guide and pinning it but then another one does it any suggestions
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Hammer Time
Ultimate Carjunky
/ Moderator
Jan 20, 2013, 5:21 PM
Post #2 of 8
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Re: 1985 gmc 1/2 ton rocker arm studs
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Are the cam, lifters and valve springs OEM?
Does it run good before they break?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Jan 20, 2013, 9:48 PM
Post #3 of 8
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Re: 1985 gmc 1/2 ton rocker arm studs
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Been there many times and nothing broke but all OE. Those studs for rockers must be the right stuff not hardware things. That 9/16th nut is the pre-set for adjustment and didn't think there was that much stress on those but it things are breaking something isn't to spec.
These are Iron Horse engines that don't usually throw surprises. Something or wrong non OE something is going on??
T
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lowboy99
New User
Jan 21, 2013, 6:53 AM
Post #4 of 8
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Re: 1985 gmc 1/2 ton rocker arm studs
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lifters and cam are after market and yes it runs fine before
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Hammer Time
Ultimate Carjunky
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Jan 21, 2013, 6:57 AM
Post #5 of 8
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Re: 1985 gmc 1/2 ton rocker arm studs
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The aftermarket cam you have could very well have too much lift and the studs can't handle it. If you went to solid lifters, that makes it even worse.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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lowboy99
New User
Jan 21, 2013, 7:00 AM
Post #6 of 8
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Re: 1985 gmc 1/2 ton rocker arm studs
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heads are stock all original
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Tom Greenleaf
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Jan 21, 2013, 7:54 AM
Post #7 of 8
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Re: 1985 gmc 1/2 ton rocker arm studs
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Something went wrong This engine dates back to th 1950s. Bulletproof in a way but changes along the way too,
Any changes to how it was intended are only going to mess up the whole show.....................
Tom
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re-tired
Veteran
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Jan 23, 2013, 10:35 PM
Post #8 of 8
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Re: 1985 gmc 1/2 ton rocker arm studs
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THis may sound dumb. How are you adjusting the rockers ? If your doing it right then you may need to pull all studs and tap holes and install threaded studs and guide plates.
LIFE'S SHORT GO FISH
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