Vortec 4.3 Rocker arms and studs

I have a 1999 Chevy Astro Van that was experiencing a very rough idle and misfire. After diagnosing the problem I determined it was a bad exhaust valve/seat. So I decided to replace the heads.


I purchased 2 remanufactured Vortec 4.3 heads, casting number 12557113. They came with everything except the rocker arms/studs and pushrods. I was expecting to be able to use the parts from the old heads. When I tried to assemble everything I found out the studs don’t fit.

Can anyone tell me what studs I need? Also, will I need new rocker arms and pushrods for these heads? Any tips or advice is greatly appreciated.



Thanks!

[Blue Bowtie]

If it were mine, I would prepare the new heads for screwed studs. If the old rocker arms and pivots are not worn or damaged, and the push rods are clean, straight, and not bent, you should be able to use them again.

Hi,

The studs are the screw in type. The problem is my old studs are not the same thread size. So I'm hoping someone can tell me which one I need.

The casting number is 12557113. I believe the heads came from a 2001 Model Vortec 4.3.

Thanks!