1999T/A30th1336

iTrader: (1)

I am building my ls1 i have mahle flat tops with 4cc valve reliefs im want my compression between 11:1- 11.5:1. i have stock heads (66.67 cc) i want to know how much i can mill off before i need to worry about my intake alighment. i was also wondering who makes the thinest head gasket and whats the thickness??

moeZ28

iTrader: (7)

My 853 heads from Lingenfelter have been milled a total of around .070" and I have just a little bit of a fit issue with the intake. You kind of have to push it into place but it doesnt crack or break or anything, its just really tight.

Slo_240sx

iTrader: (17)

Wow how is your PtV clearance on that setup?! .070 mill with a 2.02 valve 249/249 cam... Jebus.

.050 is where you should start to worry. Thinest gasket I have seen is the Mr gasket .042 but I believe they do make thinner ones.

Pwebbz28

iTrader: (31)

Mill as little as possible and use a .030-.040 cometic headgasket. After you mill so much you start to hurt the headflow.

N4cer

iTrader: (11)

Moe's pistons have valve reliefs the size of pumpkins!
Seriously, he's got some major valve reliefs.

GuitsBoy

iTrader: (4)

.050 is the rule of thumb before the intake starts to fit funky. Like the others say, a thinner gasket will increase compression more quickly than milling, plus it will tighten up your quench which is better for fuel charge mixing and reducing knock. FWIW, My heads are milled .040 and I have no fitment issues at all.

slow trap

iTrader: (22)

i's say mill .030-.040 and use an .040 gasket.that should get you alittle over 11 scr i'd say off the top of my head.

moeZ28

iTrader: (7)

I used a stock gm graphite gasket (.056") b/c they are proven to work good on higher hp than I have. And like N4cer said, I have -4cc valve reliefs in my pistons so piston to valve clearance isnt an issue. My cam is just a TREX, although a little larger than a normal TREX, which fits stock heads, and my valve reliefs are much deeper than .070". I figure my compression ratio is somewhere around 11.5:1, but I am not really sure exactly where its at b/c I dont know what my combustion chamber volume is to make a good estimate. I am guessing around 57cc though. On 93 octane pump gas, I made 453 rwhp with 500 miles on the motor with this setup. I know its got more in it, especially if I run some 110 or so octane. We will see what happens soon. My rings are also gapped for nitrous and I am gonna spray a big shot when i get some more miles on it, and get my new clutch in since mine is fried.

N4cer

iTrader: (11)

I fear Moe's car now. I'll not leave my house once he gets his bottle.

moeZ28

iTrader: (7)

There is nothing to fear with my pickled clutch, non-posi one-legged rearend thats still sportin a 3.23 gear, and of course my no-driving *** behind the wheel.

brent98gt

Do you guys think I will need to flycut my pistons when using a set of 98 heads that have been very well worked over...ferrera 2.02/1.60 valves...milled 35 thousanths...while using a tr224 112 cam?

Pwebbz28

iTrader: (31)

I highly doubt it. Checking PTV is VERY easy though.

moeZ28

iTrader: (7)

I wouldnt think there would be any cause for concern with this setup as far as PTV clearance. It should be really fun on the street with all the power under the curve you will have with that cam and ported heads. Your gonna hurt some bigger cam guys' feelings when your done.

brent98gt

I would be using tr 7.4 pushrods and a commetic gasket (thinner mls gasket). I just realy dont want to flycut, compression should be up near 11:7.

TWINK

iTrader: (10)