Stock head milling for raised compression
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Launching!
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From: milwaukee wisconsin
Stock head milling for raised compression I'm assembling my engine and was curious if there is an equation to figure out how much i can mill off the heads or if someone can guide in what should be decked off? Then what point do i have to switch to shorter pushrods? Does it even make sense to mill the heads if I plan on spraying upwards of a 200 shot?
I have a 99 LS1 block, Mahle stock bore forged pistons, Eagle rods in stock length, GM graphite head gaskets, Stock 99 heads, TSP 233/239 cam .605/.605 .
Thanks for the help
JEFF
I have a 99 LS1 block, Mahle stock bore forged pistons, Eagle rods in stock length, GM graphite head gaskets, Stock 99 heads, TSP 233/239 cam .605/.605 .
Thanks for the help
JEFF
I'd rather buy some 5.3 heads instead of cutting good LS1 heads myself. I got brand new 5.3 heads on Ebay for less than $300 shipped and they flow similar to stock LS1 heads stock vs stock, and they respond to porting and larger valves well too.
For the price, it's almost just as cheap to do 5.3 heads anyway because the milling will cost you money for machine work, plus you can sell off the used ls1 heads on ebay to further offset the cost.
For the price, it's almost just as cheap to do 5.3 heads anyway because the milling will cost you money for machine work, plus you can sell off the used ls1 heads on ebay to further offset the cost.
https://ls1tech.com/forums/showpost....2&postcount=41
It takes .007" milling to remove 1cc from an LS1 head
It takes .007" milling to remove 1cc from an LS1 head
With that cam, im not sure you can mill anything... Are you a machinest? Do you have a lathe? If so, make your own valve relief / flycutting tools. Its fairly easy, but you need a junk head with the valve seats removed. You can pick one up pretty cheap. Once you flycut, you can mill as much off the heads as you like (within reason) and not worry too much about the cam not fitting in there.
Pics: http://www.ihearyou.com/~tony/pictures/flycut/
Pics: http://www.ihearyou.com/~tony/pictures/flycut/
Thread Starter
Launching!
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From: milwaukee wisconsin
the MAHLE pistons have valve relief in them. off the top of my head I'd like to say .100" deep valve relief. I am a machinist as to why i'd be doing the work
JEFF
JEFF
Whoops, I should open my eyes a little wider. I read as stock pistons, missed the mahle part. Anyway, you can mill up to .050 off before you start running into problems with intake alignment. Im running around 11:1 compression with heads milled .040 and roughly 1 cc valve reliefs. Your reliefs are probably closer to 2 or even 4 cc. Id mill somewhere around .040 or possibly .050 if youre feeling saucy. Then run the mr. gasket .042 gaskets. A buddy of mine has these and has great results. The MrGaskets are dirt cheap, but if youve got the money you could get cometics.
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Originally Posted by Xtnct00WS6
https://ls1tech.com/forums/showpost....2&postcount=41
It takes .007" milling to remove 1cc from an LS1 head
It takes .007" milling to remove 1cc from an LS1 head
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Originally Posted by 99SLOWC5
thanks for the help, The pistons have 4cc valve reliefs in them. I was looking at milling .040" off. Does my pushrod length then change also?
JEFF
JEFF
Originally Posted by 99SLOWC5
Does my pushrod length then change also?JEFF
my heads are milled .030 and i have cometic .036 gaskets
Originally Posted by vanilla89
you need to check pushrod length when you change cam's,mill the heads,or change head gaskets.
my heads are milled .030 and i have cometic .036 gaskets
my heads are milled .030 and i have cometic .036 gaskets
Calculations are close enough. Stock lifters take a wide range of preload. Stock cam base circle is 1.550, comp cam grinds are usually 1.450, so a .050 smaller pushrod is usually needed. Although, stock pushrods are 7.380 not a true 7.400, so that factors in. Heads are right at 4.750" thick, but just keep track of how much you mill. Stock gaskets are anywhere from .052 - .060 depending on the year. 99's were still composite gaskets, .052 - .054 compressed thickness. Add it all up and decide.
Originally Posted by vanilla89
if you want it to run right "caculations" are not close enough
haha well thats a good peice of info, and i've gotta a question as well to boot. MS3 cam w/ stock heads milled .030 and stock multi-layer steel gaskets. I've got Mahle -2cc valve reliefs,...bout to toss it all back together, should i be good to go and run just fine? Also have 7.4 PR's.
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Joined: Mar 2004
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From: BFE
Originally Posted by 98REDZ
haha well thats a good peice of info, and i've gotta a question as well to boot. MS3 cam w/ stock heads milled .030 and stock multi-layer steel gaskets. I've got Mahle -2cc valve reliefs,...bout to toss it all back together, should i be good to go and run just fine? Also have 7.4 PR's.
