I thought I had all the big questions sorted out for my rebuild but I just picked up my head from the motor shop and I think I've got a problem. I dropped it off to have it hot tanked and 'checked out' and when they told me it needed shaving I said to go for it, although I did tell them it had already been shaved at least once and I wasn't sure if that would be a problem. Well I got it back and it's between .1" and .15" shorter than spec! I've only got a 3" mic so I'm measuring with a good metal square rule, I only trust it to about .05 but that's enough to tell me I've got an issue... I don't think the shop even measured it before shaving cause I assume if they had they would have checked with me if it was worth working on. Guess it's my fault for not checking myself.
So, can I work with this? Right now I just need this truck to stop sucking up money and start helping earn it. I'm not worried about a little lost power as long as I'm not going to damage the engine. I am worried about piston clearance and timing issues. Can someone with more experience with these engines offer some advice? Everything else on the head is in pretty good shape so I really want to use it if I can. This is one area where the FSM gives me nothing, it doesn't even have a max deviation listed with the head height.

 

Oh, this is a 1975 20R

 

Ask the machinist about head shims as per the other thread.