Breaking rocker arm studs

cadillac_al

Veteran Member
Apr 22, 2015
1,100
Maine
result of my push rod checker. valve on the left has the checker set at 7.122 and this is what the gm part number # 10241740 as 5/16 7.122 inch long. the valve on right has the push rod that i got from chevrolet performance parts that describes as being 7.122 also but the actual measurment is 7.195 rods measured with digital caliper. the lash was set with top dead center compression stroke on #1 cylinder which is the one in picture and since my lifters were pumped up i made a half turn after zero lash. would you agree the pic on the left is ideal and the one on right is to long. spring coil bind is ruled out i have more than. 060 clearance
Wouldn't those longer push rods eliminate your .060" valve spring clearance? A lot of people bend valves quite easily without damaging the rocker arm studs. I think you have some extreme contact going on somewhere.

I bent some valves a few years ago when I tried to install my timing gears witout my glasses on. I got my squares and circles mixed up on the timing gear and bent the valves before it ever started. No damage to the rockers at all.
 

biker

Veteran Member
Gold Member
Dec 7, 2014
5,067
Canada
Wouldn't those longer push rods eliminate your .060" valve spring clearance? A lot of people bend valves quite easily without damaging the rocker arm studs. I think you have some extreme contact going on somewhere.

I bent some valves a few years ago when I tried to install my timing gears witout my glasses on. I got my squares and circles mixed up on the timing gear and bent the valves before it ever started. No damage to the rockers at all.
Yes. Piston to valve hit won't break a stud. Has to be bottoming on the valve guide boss.
 

tom3

Veteran Member
Aug 1, 1999
14,660
ohio
Did that motor come stock with screw in studs? Machined and threaded bosses could be out of alignment putting major tension on the studs when installed?
 

JohnnyD

New Member
Aug 6, 2022
9
Im taking Rascals advice and pulling cam and inspecting and verifying for correct cam and any tell tell signs . I also got my hands on a set of original new GM rocker arms and comparing them to the aftermarket ones that i purchased was a difference. the travel slot for the valve tip on GM originals had a more profound travel while aftermarket were low profile and slot for valve tip were wider allowing more side to side movement than the gm rocker. Not sure if any of that would cause a problem but i feel better with original part. I need to take a week vacation to dedicate my time to this project cause i can only work on it in spare time. I bought this brand new in 97 put 400,000 miles on it and a lot of history and good memories. Promised it to my grandson. With the help with all you guys it will happen. Thanks
 




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