How much can you safely mill your stock LS1 heads without worrying about the intake manifold matching up? I've heard .03500 is the safety net for a lot of people, but I'm not totally sure that's accurate.

What is the resulting compression ration?
i.e .010 = xx.x CR
.020 = xx.x CR
.030 = xx.x CR
<img border="0" alt="[Firebird]" title="" src="graemlins/formula.gif" /> etc., etc...

Would I need custom tuning if I were to do this to a basically stock car? How much power gain are we talking about if I go to the maximum safe limit?

Pros? Cons?

 

Would you be able to run stock length pushrods?? I'm running an XER grind and taking .030 off. I thought a 7.350 pushrod would be needed.

 

You really need to measure a cams base circle, but it seems [most] of these aftermarket cams have somewhere between .025" - .030" less base circle (distance from the centerline to lobe heal) than the stock cam. That in itself would require longer pushrods.

However, milling the heads .030" would require a shorter pushrod.

The combination of the two (milled head & cam combo) brings the lifter preload back to stock with the stock 7.40" pushrod.

<small>[ October 07, 2002, 11:07 PM: Message edited by: Kimchee and Rice ]</small>

 

I dont know for sure... but I think these are valid:

.030 = 10.8:1 (i think this is the same as 5.3 liter heads)
.050 = 11.1:1

 

You can safely mill .050 from an LS1 head with 7.350 pushrods. I did <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Reckless:
<strong>You can safely mill .050 from an LS1 head with 7.350 pushrods. I did <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Did you notice any power increases? Any leaks from the intake manifold or other problems? No pinging, I hope...

I run 93 octane all the time and I have the stock cam.

<small>[ October 08, 2002, 05:25 PM: Message edited by: NJones ]</small>

 

I have heard that in general milling 0.010 will drop about 1cc of cylinder volume. Not sure if that is true, but it seems to make sense. For the overall compression, it will depend on the heads starting volume.

 

I measured stock 2001 5.7 chamber and it was 67cc, i had my heads cut .035" and they measured 62cc after, if 67cc is 10.1 to 1, then 62cc is 10.7 to 1. I have no pinging issues with head work and cam, even with HPP3 power programming installed.

 

Actually there are publications out there that say that the LS1 heads have a 66.67cc head which gives 10.1:1 and the LS6 heads are 64.45cc or 10.5:1. If that's true a 62 cc head would be around 10.95:1. However I had my heads milled .015 and it produced 65.8cc (10.25:1) which was not enough. Milling an additional .008" will give me the desired 10.5:1 and help compensate for the smaller base circle of the 02 LS6 cam. Also a good valves job will make the valve tip sit higher and help correct the geometry of the higher lift.