99SLOWC5

iTrader: (8)

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

SS_bnoon_SS

iTrader: (3)

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.

99SLOWC5

iTrader: (8)

The milling is free as I will be doing it myself.

I'll look into some 5.3 heads though

JEFF

Xtnct00WS6

iTrader: (8)

https://ls1tech.com/forums/showpost....2&postcount=41

It takes .007" milling to remove 1cc from an LS1 head

GuitsBoy

iTrader: (4)

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/

99SLOWC5

iTrader: (8)

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

GuitsBoy

iTrader: (4)

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.

GuitsBoy

iTrader: (4)

I think its .006 for an ls1 head and .007 for an ls6 head due to the double quench pads.

99SLOWC5

iTrader: (8)

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

GuitsBoy

iTrader: (4)

I kept the 7.400 pushrods milled .040, but as it is, im 11 over the stock preload. im pushing it. you might need to tone it back down to 7.375 if you run a thin gasket.

vanilla89

iTrader: (8)

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

GuitsBoy

iTrader: (4)

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.

vanilla89

iTrader: (8)

if you want it to run right "caculations" are not close enough

GuitsBoy

iTrader: (4)

I strongly disagree. Plenty of people run perfectly fine having only to choose from pushrods in .050 increments. Some sponsors may stock .025 increments, but thats it. To get any more accurate than that, you need to order a custom set, or run adjustable rockers. Its a hard sell to tell 95% of the heads/cam guys out there that their motor are not running right / well. IMO theres no need for the added expense. If youve got some well organized data that youd like to share with us to build your case, please do, however these stock lifters take a wide range of preloads. Anywhere from .020 to .120 will work, even if its not the ideal setup. Some cam manufacturers actually suggest runing less preload as its suggested to reduce the possibility of pump up at high rpms. Different schools of thoughts will place "perfect PR length" all over the board. Running correctly becomes somewhat subjective at this point.

98REDZ

iTrader: (3)

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.

PREDATOR-Z

Yeah 7.40 will work

98REDZ

iTrader: (3)

and i'll have no PVC issues at all running that setup upwards to 7K RPMS?

PREDATOR-Z

PTV is no concern, as long as your shortblock can handle the rpm.
I would optimize DCR and quench on that setup

98REDZ

iTrader: (3)

explain if ya dont mind, of DCR and quench. Thanks. but yeah my shortblock is in the process of getting entirely rebuilt right now.