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Which one you guys prefer? I have always used Copper Spray for my MLS gaskets in my previous combos, but I have recently heard that a lot of people prefer the Holymar.
 

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whichever is handy and whichever is cheaper at the time....as far as I am concerned, spraying MLS gaskets is all about sealing up imperfections on the block/head surfaces and filling up any removal of the MLS gasket coatings after they are removed from their last use...
 

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You shouldn't be using sealer with them at all. They are made to be used as is. But....the heads and block also have to be properly surfaced, and generally require a substantially smoother surface finish than other gaskets.
 

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You shouldn't be using sealer with them at all. They are made to be used as is. But....the heads and block also have to be properly surfaced, and generally require a substantially smoother surface finish than other gaskets.
Some MLS gaskets are bare steel, and the water passages, etc can benefit from a light copper spray coating. Some have a little bit of a coating from the factory, and do not. I'm not up to date, but in the beginning, Cometics were bare, and when Fel-Pro came out with them, they had a coating on them, and did not need sprayed.
 

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Last three BBC I built and used Cometic head gaskets they had a coating on them, I never have used a sealer with brand new gaskets. I have even reused a set of Cometic gaskets and still didn’t use a sealer and no issues or leaks.

Steve
 

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on my 1st reuse. seperated & cleaned them. sprayed one layer at a time with hylomar. first layer sat it on. cleaned 2nd and sprayed it sat it on etc. that way gone tacky before tensioned it down. so far no leaks
 

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It is recommended by most, if not all, gasket manufacturers that MLS gaskets are to be installed dry, with no sealer. MLS gaskets are designed to move and slide across the sealing surface, that is why smooth head and block surfaces are so important. Sealer should not be used with these gaskets under any circumstances.
BTW, I have never seen Fel Pro, Cometic, nor any other brand of MLS head gasket that does NOT have coating of some sort on the surfaces . . . . . .
 

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It is recommended by most, if not all, gasket manufacturers that MLS gaskets are to be installed dry, with no sealer. MLS gaskets are designed to move and slide across the sealing surface, that is why smooth head and block surfaces are so important. Sealer should not be used with these gaskets under any circumstances.
BTW, I have never seen Fel Pro, Cometic, nor any other brand of MLS head gasket that does NOT have coating of some sort on the surfaces . . . . . .
 

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I recently spoke to Cometic about re-using their MLS head gaskets. While they recognize it’s being done, they do not recommend it as the problem is the raised beads have been crushed and do not offer the required crush the second time around. This is only AFTER the gasket has been through a heat cycle. Does not apply to mock-up engine assembly to check clearances.
And they did say that if you INSIST on a coating, then hylomar is the one to use.
 

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I recently spoke to Cometic about re-using their MLS head gaskets. While they recognize it’s being done, they do not recommend it as the problem is the raised beads have been crushed and do not offer the required crush the second time around. This is only AFTER the gasket has been through a heat cycle. Does not apply to mock-up engine assembly to check clearances.
And they did say that if you INSIST on a coating, then hylomar is the one to use.
Of course they said not to reuse them, they are in the business of selling new gaskets.
 

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I recently spoke to Cometic about re-using their MLS head gaskets. While they recognize it’s being done, they do not recommend it as the problem is the raised beads have been crushed and do not offer the required crush the second time around. This is only AFTER the gasket has been through a heat cycle. Does not apply to mock-up engine assembly to check clearances.
And they did say that if you INSIST on a coating, then hylomar is the one to use.
I typically test several sets of heads, using the same gaskets and never have a problem. This is with a minimum 220* water temp.
If we ever coat them, and we have in the past for various reasons not really related to sealing, we use copper coat.
 

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Anyone ever run into small block cometics having the rivet tab interfere with the motor plate in front? I bent the tab to clear, which I didn't feel great about.
 

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Anyone ever run into small block cometics having the rivet tab interfere with the motor plate in front? I bent the tab to clear, which I didn't feel great about.
I bend the all the time AFTER they are torqued in place, BBC must be done on 2 corner as it'll run big pushrods...
Sbc I haven't had to, there is none in the front, you must be talking LS based engines.
 

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so hylomar around the water holes ?

when people are coating are they doing between the layers or just on surfaces to the head and block?
 

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I bend the all the time AFTER they are torqued in place, BBC must be done on 2 corner as it'll run big pushrods...
Sbc I haven't had to, there is none in the front, you must be talking LS based engines.
Gen 1 sbc
Nothing with the pushrods. But they put the tabs in front and back of these gaskets. I would feel better about bending them after torquing. But if I am replacing in chassis, I'm kinda stuck.
 
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