I compression tested the 98 LS I have the ghetto way - hooking up flywheel, trans, starter and jumping it. I got around 175 all the way across except for one of around 160-165. We put some oil in that cylinder and got like 185, let it sit for a bit then did it again and got 175. Is that variance a big concern?

My dad thought that maybe we weren't getting the comp. tester tightened consistently so we rigged up a pipe to replace the hose and got like 175 all across.

I guess just the fact that the one cylinder jumped when we put oil in it is my concern but is it enough to take the engine back and have to find another one?

 

15 psi is acceptable range for all cylinders. you would be in the recommended factory specs.

hence 160-175 psi is ok.