Author Topic: cylinder heads  (Read 3250 times)

MarkB

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cylinder heads
« on: August 19, 2009, 04:01:48 PM »
Hi
Thanks for help the last time around.  We had a response that brings up another question.
The photo of a pair of cylinder heads show threaded rocker arm studs.  I think they should be pressed in for the 1969 Z28.  Which is correct?
MarkB



william

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Re: cylinder heads
« Reply #1 on: August 19, 2009, 05:17:35 PM »
'69 Z/28 heads used pressed-in studs. If the heads are hot-tanked during a rebuild it seems to affect the press fit. If one of them lifted the back-yard repair involved drilling a hole through the stud & boss and inserting a steel pin. If the stud lifts again it will break off the stud boss.

I believe some older Corvettes used a plain threaded stud; the '70 LT-1 used a screw-in shoulder stud with a push rod guide plate. Requires hardened push rods.

Were I to rebuild a 302 today it would not have pressed-in studs.
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Stingr69

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Re: cylinder heads
« Reply #2 on: August 19, 2009, 05:46:22 PM »
I would agree with William - There were no screw-in studs from the factory before 1970. They were used on LT-1's and I believe 350/350's from 1970 and after that. Also used on the L-82 Vettes which had the same 350/350 cam. It is a common and inexpensive mod. The pushrod holes will need to be drilled open and the bosses are milled down. The threads are then tapped and you will need pushrod guide plates.

-Mark.

Dusk Blue Z

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Re: cylinder heads
« Reply #3 on: August 20, 2009, 01:00:22 AM »
Mr. Gasket makes a replacement screw in stud that you don't have to mill down the bosses to install. Pull out the press in studs, tap the hole, and install with some J-B Weld. You get the peace of mind of the screw in stud with the original look. http://www.jegs.com/i/Mr-Gasket/720/1076/10002/-1
Mike
Mike

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1969 Z-10 Under Construction