hey my brother has an 2002 silvy and wants to put a cam and mill head that he has a set of 317s that he was wonder if u can mill them down farn enought to raise the cr in a 5.3? if u guys could help out thanks alot

 

can you mill them yes to get the cr up no! the stock 5.3 heads are 61cc and the 317's are 72 cc chambers!

 

If ur brother has a 5.3 and he wants to mill his current heads just to let u know they r not 317s.. now if he has 317sa well I don't think its a good idea to put those on. U will need alot of milling to get it back to stock compression. Don't think u can even mill that much!

 

Ok thanks he was just wondering I figured u could mill the like .60 to make them better for it.lol thanks again

 

ok guys now my bro wants to know if he can mill 243 heads to get more cr out of his 5.3 cuz he wants like 10.1 ish for it any ideas for him? thanks

 

That you can do. mine are milled .030 and I'm going to run a .040 head gasket, should put me at somewhere around 10.15:1... If I would have been the person to do the machine work to them, I probably would have milled them another .010

 

personally id do the 243's .040 , thats what im about to do soon as i find a shop local to do the milling

 

I believe like. 28 returns them to stock compression so .40 sounds about rt.. pick up ur compression a bit

 

all right thanks guys glad to have ur help and what thickness gasket .40 or thicker and ill tell him to take .40 off the heads thanks again

 

Stock gasket, I believe it's .051.

Shaving .040 and running a .040 gasket would be too tight for my liking, it'd be like shaving the heads .051

The only reason that I'm using the .040 gasket is because I bought my heads already milled .030 and I don't feel like going and having them milled another .010 since the nearest machine shop I trust to do it is over an hour and a half away.