now that I have my heads off, my buddy suggested getting them milled. my uncle ownes a machine shop so i got to thinking that it might not be that bad an idea <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> . questions though- i have aftermarket pushrods to go in- same length as stock, along with 918 springs. decent cam is going in too. how much is safe to mill it with everything else remaining stock. ive read about .030? not sure on what head gaskets im gonna get either. prolly just pick up some stockers or whatever speedinc. has in stock.

second question- if he is able to p/p the heads, what are some suggestions for doing it? i dont think hes over done ls1 heads before (or any heads for that matter). anything that i can tell him which may help a little would be greatly appreciated <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

also- now that i have the heads off, am i going to need new head bolts <img border="0" title="" alt="[Sad]" src="gr_sad.gif" /> wasnt planning on taking the frickin heads off, but you know how that goes.

 

If you want to still use your stock length pushrods, I would only take off ~.015".

If he has never messed with a set of heads, don't let him mess with them. It could actually hurt you more than it helps. I would only let someone experienced with porting heads mess with them.

Yes, you do need new bolts. The bolts are not reuseable.

 

only .015 <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> is that even worth the trouble then?

i wasnt expecting him to fully port them, just clean up some of the imperfections a little. hes obviously not an idiot if he owns a machine shop so i have a little faith in him <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

<small>[ June 30, 2002, 07:48 PM: Message edited by: DriveATransAm ]</small>

 

.15 would be worth it but I have mine milled .30thous and have shorter pushrods for my heads.

 

Heck, if you want compression just have them milled .030 and use 7.35 pushrods.

 

Hmmm...too many H/C cars around our area these days. Maybe it's time I call ATI <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

Roy, I think you'd be better off just getting some heads (already filled ported, pocketed and polished) by someone who knows LS1 heads. The real only benefit of milling them would be to gain compression which can be done with a filled in combustion chamber that is ported and polished (like most head people do). With Milling of them not only do you run into the problem of valvetrain geometry (provided you already aren't putting in a mountain cam <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> ) but I'd be concerned about upseting the roll, swirl and tumble effects of the combustion chamber by cutting it down. Not that it would, just something to think about.

Just my $.02. For the money, I think you'd see better results from a properly set up set of heads.

Of course a cheap alternative if you were adimate on milling them, would be to pick up some stock, used LS1 heads and play with those.

 

obviously a set of "real" heads would be nice. but seeing as how i dont have the money for a real set <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

Dump the G/F, that'll eliminate the cashflow problem. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

Sorry I wasn't there on AIM yesterday, I was running around like a chicken with my head cut off.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by CMNTMXR57:
<strong>Dump the G/F, that'll eliminate the cashflow problem. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">already did <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

picked up the cam today.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DriveATransAm:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by CMNTMXR57:
<strong>Dump the G/F, that'll eliminate the cashflow problem. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">already did <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

picked up the cam today.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You are leaning towards the darkside everyday young one I see we have trained you well. <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />

 

Good Boy, Roy!

It comes down to a matter of priorities. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

after the cash i plopped down today, i think the gf was cheaper <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

No, no, no!! Trust me, the G/F if not now, would at some time become more expensive. Especially when jewelery and other expensive gifts start adding up.

In the end, a standard accounting measure of R.O.I. (return on investment) will favor the car. That is unless the two of you screwed like jackrabbits 24-7.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by CMNTMXR57:
<strong>Roy, I think you'd be better off just getting some heads (already filled ported, pocketed and polished) by someone who knows LS1 heads. The real only benefit of milling them would be to gain compression which can be done with a filled in combustion chamber that is ported and polished (like most head people do). With Milling of them not only do you run into the problem of valvetrain geometry (provided you already aren't putting in a mountain cam <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> ) but I'd be concerned about upseting the roll, swirl and tumble effects of the combustion chamber by cutting it down. Not that it would, just something to think about.

Just my $.02. For the money, I think you'd see better results from a properly set up set of heads.

Of course a cheap alternative if you were adimate on milling them, would be to pick up some stock, used LS1 heads and play with those.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The best advice here is that you need to get some professionally done heads.

If you wanted to play and you can get the heads milled a set of 6.0L truck heads would work really well. They have a better port then the LS1 heads. Still a good set of CNC heads is the way to go.

BTW: welding in the combustion chamber is not the common way to increase compression. Flat and angle milling are. As for the geometery you would only have to change the pushrod length if the hyd lifters can't make up fo the difference. As for affecting the swirl. True some combustion chambers like the GMPP Fast Burn heads have a chamber that is optimized and milling can hurt it. Cutting down a combustion chamber can help the swirl and quench. The swirl is determined somewhat by the chamber but more by the intake port on the head.

 

well ****, now heres a situation. my uncle closes for a long weekend tomorrow at 4. that means i wont be able to get them milled till next week <img border="0" title="" alt="[Sad]" src="gr_sad.gif" /> . i dont think i can wait that long, i need my car now <img border="0" title="" alt="[Sad]" src="gr_sad.gif" /> . ugh. how much is .015 worth exactly? 10.5-.6? whats that equal in hp. would i be better off going with a thinner gasket? i hate when **** like this happens.

 

Something is better then nothing. I would rather have a small mill and port clean up then nothing. However, you should consider the head and cam swap. You wont be disappointed if you get them from a quality supplier i.e. MTI/ARE/ThunderRacing etc.

 

CAM IS BEING SWAPPED

I HAVE NO MONEY FOR HEADS SO EVEYRYONE QUIT SUGGESTING IT <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Well, this weekend, I installed a 216/216 cam and my own ported heads. Some people think that LS1 heads are magical. They are not. Sure, places more familiar with them will be able to extract more power. I D shaped the exhaust port, removed the rocker boss on the intake port and slightly enlarged it. I also smoothed the valve guides and swirl ramp. I never did flow test these heads, but I know they flow much better than they did and it was free. I'll have to report track times soon. As for milling, one full point in compression will add 3% more hp. So on an LS1, if you raised the comp. to 11.1:1 on a 300hp motor, it would add 9 hp. Not a large return, but hp isnt everything. It also improves engine efficiency and throttle response. I personally didnt mill mine. I wanted to save the $100 it would cost and didnt want to run into detonation issues. I was going for a budget buildup.

Brad

FWIW, I personally looked at GMs ported LS1 and LS6 heads. My heads looked just like the GM LS1 heads, except mine were smoother since they were not CNC'd. I measured the ports and took careful note of what was exactly machined.

<small>[ July 03, 2002, 05:37 PM: Message edited by: MyLS1Hauls ]</small>

 

If you mill the heads you will probably want to go with a 7.350 push rod.

If you want to spend a little $$$ I might know a place that will do some stuff to your heads.

PSJ