Cometic sucks...how about milling these heads?
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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![Bang Head](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_banghead.gif)
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Thanks.
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
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Last edited by camz28arro; 05-16-2010 at 07:16 AM.
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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.
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.
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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?
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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?
Last edited by camz28arro; 05-16-2010 at 08:31 AM.
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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.
Fyi I had my stock 243's milled 0.015, I was shooting for a 62cc hamber size.
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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.
Also, if this is the first time installing those heads, you should have them check for porosity and cracks.
Last edited by vettenuts; 05-17-2010 at 04:18 AM.
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Cometics (and GM) also have flatness requirements. Has that been checked? Can't blame the gasket without know 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.
Also, if this is the first time installing those heads, you should have them check for porosity and cracks.
Has nothing to do with the gaskets, we have used them for years on many different engines and NEVER had a leak.
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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.
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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.
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.
Last edited by camz28arro; 05-16-2010 at 06:25 PM.
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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.
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.
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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.
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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.
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.