1972 gmc 402

[backagain]

hi
issue is this: 1972 gmc pick up 402 th400.
low compression # 5,7,6 at 25 lbs
pulled valve covers and on rt side 3 rocker arms loose and sideways.
intake pushrods bent. left side #6 same thing
only intake pushrods look bent but will pull all rockers off to check all.
the truck has only run to drive home 6 miles 1-1/2 years ago.
this is a project so wont pull heads now, but know I have to.
any good mechanics out there might have idea?
thanks

[LockDoc]

Originally Posted by backagain

hi
issue is this: 1972 gmc pick up 402 th400.
low compression # 5,7,6 at 25 lbs
pulled valve covers and on rt side 3 rocker arms loose and sideways.
intake pushrods bent. left side #6 same thing
only intake pushrods look bent but will pull all rockers off to check all.
the truck has only run to drive home 6 miles 1-1/2 years ago.
this is a project so wont pull heads now, but know I have to.
any good mechanics out there might have idea?
thanks

Check the rocker arm studs to see if they have pulled out of the head.(check the length above the head with a couple that are still tight) I had two of the intake studs pulled on my '70 C-20.(#1 & #6) I replaced one of them and double nutted the other one and drove it back in with a brass hammer. Been running great for the last 3 years.

LockDoc

[hamjet]

I thought all bbc heads had screw in studs, may be wrong. Has the cam been changed, too high lift they could be touching the pistons, bending the push rods. a motor with high mileage with heavy valve springs could have worn the rockers or broken rockers causing them to lean sideways which will bend the push rods. once they lean like that the rockers cut into the studs, time to check them all out...