camz28arro

iTrader: (12)

I figured if I used copper spray I wouldn't be one of the many people on here that had them leak..Wrong. Cometics suck and I'm done playing around with them. Also if I can see the one leaking this bad, who knows if the other is leaking coolant into the oil or cylinder too. I've decided to go with some good old, reliable, cheap GM MLS 0.051 gaskets and get my heads milled.

I have PRC LS6 1.0 heads and a TR224 cam so would I just need to take that 11 thousandths off to keep the 11.0:1 compression or would I need to take nearly 20 thousands off since it's a head chamber. I hear I shouldn't exceed 0.030 and I'm guessing there will possibly there will be PTV problems above that also.

Also how much would milling usually cost? I know it would have been free if I just got it done through TSP when ordering and I would have saved $100 on head gaskets and a lot less aggrevation Thanks.

JimMueller

iTrader: (9)

I've read about the problems also, but I guess I've been lucky. Re-used my first set of Cometic's using copper spray without any leaks. I'm going with GM gaskets on the next motor only because it gives me the compression numbers I want and is conveniently cheaper than Cometic.

If you want to maintain the same compression, just have the difference in compressed head gasket thickness milled off your heads.

The accepted standard seems to be .006-.007 to shave off 1cc. TSP quoted me $75 a few years ago to mill my 5.3's to 59cc before they shipped, but when we checked them at the machine shop they were 62cc. Each was skeptical of the other shops quality control, but TSP graciously sent me the amount quoted by the local shop to mill the heads to get 59cc. I want to say that was around $100.

camz28arro

iTrader: (12)

So I would need a 61cc combustion chamber to get about the same 11.0:1 compression as with the cometics, which did I mention I hate?

3cc = 0.020 in. milled

Which is 9 thousandths more than the thinner gaskets, but my cam is small so it should be fine right?

massls1guy

iTrader: (9)

As long as you aren't using nitrous or boost the GM graphite gaskets are a good option. Compared to MLS they are a lot more forgiving to imperfections in the block or head surface. I have about 55k miles on GM graphite gaskets with my current combo.

Fyi I had my stock 243's milled 0.015, I was shooting for a 62cc hamber size.

SweetS10V8

iTrader: (4)

Cometic gaskets have an RA(roughness average) requirement. Did you have you heads ann block machined to the required RA so the gaskets would seal?

vettenuts

iTrader: (4)

Cometics (and GM) also have flatness requirements. Has that been checked? Can't blame the gasket without knowing the condition of the block and heads. GM has similar, less stringent requirements. Better check both Ra and flatness before moving on or you could be in the same boat later down the road if something is out of specifications.

Also, if this is the first time installing those heads, you should have them check for porosity and cracks.

ATVracr

iTrader: (5)

What he said. ^

Has nothing to do with the gaskets, we have used them for years on many different engines and NEVER had a leak.

FRUSTRATED T/A

iTrader: (13)

Give the solid copper ones a try. Ill try and remmber the brand i used, but their half the coste. They have a sticky glue on them also. Arp head studs and retrurqe them every so often. If your looking for the best have the heads and block o-ringed. Dont know what bolts your using but the stock gm ones are not to be reused. YOU must make sure you dont over tighten them also as the bolt will over stretch and wont carry load as well.

ATVracr

iTrader: (5)

He's got some stock casting heads and a 224 cam, dont think he needs copper head gaskets and O-rings. LOL

02*C5

iTrader: (1)

lol...buahahahaha...wait unless those stock heads are milled and are amking like 15:1 compression


he will be fine with cometic or mls gaskets as long as they are set up correctly.

cencalrx7

iTrader: (7)

I also recently had a set of Cometics gaskets fail on me.....From now on only GM

corvet786c

iTrader: (6)

I am using gm mls gaskets on my afr heads and no problems. My heads are milled to 62cc too.

camz28arro

iTrader: (12)

I may try another cometic but I would like to know my original question of how much I need to mill the prc ls6 heads to get to a 11:0-1 compression. Then I will decide from there.

I'm guessing it would be 0.020 and how far down can I mill the heads with a small tr224. I saw one person had them milled 0.030 and had 0.068 PTV clearance, 0.051 gasket.

I hope everybody can understand why I am mad at the gaskets and why I would want to use Gm graphite ones.

02*C5

iTrader: (1)

You need 61CC chambers for 11:1 and Ls heads its .007 for every 1CC so your looking at .021 milled to get where you are wanting to be.

Now gaskets are only as good as there set up I don't know you, your ability or who ever did it, but again the gasket is only as good as the set up. Plenty of people running cometic or gm and many have had bad luck with both yet many more have found them to work just fine.

Good luck with the project.

FRUSTRATED T/A

iTrader: (13)

i mentioned the copper ones because they were much cheaper or close to the same as stock gm ones. So its no big deal to run them. I dont think he needs to 0-ring ither i just throught it out their. The copper is reusable like others also and you dont have to scrap left overs off the deck for ever.

camz28arro

iTrader: (12)

Thanks for the info, I did spend a real long time cleaning the block but didn't spend a lot of time on the head since it was brand new. There were a couple of tiny burrs but not from where it was leaking. Just finished cleaning the block, head, bolts, holes and getting the gunk out of the threads again, fingers crossed for try two.

camz28arro

iTrader: (12)

Does this head milling finish seem kind of rough? Usually the cutting lines aren't as noticable as on the stock heads to the right.

ss1

iTrader: (32)

The cut looks like that of a set of iron Vortec heads I bought that were right from GM a few years ago. Any time i've had a set of heads milled they have been much smoother in appearance than that.

Btw, why do you "need" 11.0:1 compression?

SweetS10V8

iTrader: (4)

It just means when they milled the heads, the speed they cut the head was faster. The speed they cut accross the head determines the RA finish. THis is what you need correct for cometics to work well.

cacmanjr

iTrader: (14)

SCE maybe?