engine rebuild question

[JSD69Vette]

I'm getting ready to rebuild my '87 GN and have some questions about what I should do with the machine work.

I've spoken to Jack Cotton and he said unless the crank or rods are bad I can stay with the stock rotating assembly to suit my application of daily driver and mid-12 car. So that's what I'll do. I will get some forged pistons.

My question's are:

Should I have a stud girdle machined into the motor, I'm thinking about the RJC girdle?

If yes, will it interfer with clearance at the cross member?

Is there a good online source for detailed instructions on porting the stock heads and intake?

How about a source for checking lifter pre-load?

Thanks in advance for the advise.

 

[86 TR]

There has been some guys running high-tens with an unopened original engine!! The stock pieces are very strong as long as you don't detonate it.

If you want to go mid-12's I wouldn't buy a girdle.. Instead I would just buy the 2 center billet main caps and that should work fine for you. Ive heard of guys running the 2 center billet caps and stock cranks, and rod down into the high tens. But thats what everybody says: I only want to go this fast and then faster, faster, faster. Whatever fits into your budget.

Second when it comes to porting the heads personally I would buy a set from one of the vendors on this board. I know Champion makes some really nice cnc ported stock cast heads for about $1000. Weber makes some nice ported heads too. You could even scout out the parts for sale section too. Im not sure where you could get some porting templates though.

The best way I have checked lifter preload is get an adjustable pushrod from summit or wherever. On my car I adjusted the pushrod to zero lash then went one full turn tighter. That netted me about .020 thousandths lifter preload. Then I had a custom set of pushrods made for me. But you can buy a set of adjustable chrome-moly pushrods from some vendors. I think as long as you keep the lifter preload between .015-.030 you should be fine. If I remember correctly I think when GM originally built these engines they had alot more than that. My stock untouched engine had .060 preload. So once I had the block decked to true it up and the heads I had way too much preload.

HTH

 

[Tom Walker]

ARP's

for mid-12s, good bolts and a good tune is all you should need. tons of our 100k mile unopened motors are running low 12s/high11s with alcy, no Knock.

 

[Dustin27987]

preload

what is lifter preload