Switching from Copper to Cometics

General engine tech -- Drag Racing to Circle Track

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la360
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Switching from Copper to Cometics

Post by la360 »

For simplicity, I am planning on switching from copper to Cometic head gaskets. My biggest question, am I going to have to machine out the o-ring groove in the blocks deck surface. Generally, what diameter wire is used?
Thanks
AL...
ICTCrob

Post by ICTCrob »

Deck the o-ring groove out of the block, try to find a wet stone grinding machine if you can. Order the cometics in whatever thickness to get your P to H and P to V where you would like. Smoother surface the better.

-Rob
Trev
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Post by Trev »

Hey LA

I had the same problem as you with my Holden, I couldnt deck the block as I had already ordered my pistons.
I flat filed the the stainless rings so they where just short of flush with the block, then wet sanded with 600 wet and dry.

Did 6 runs two weeks ago and not a problem.

Trev
John Haskell
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Post by John Haskell »

Al,

I have 'O' ringed tons of heads through the years & the file method is used all the time since the swich to Cometics. The main differance being, I recomend the customers remove any steel wire & install copper wire. The surfacing of the copper is fairly quick & may save the deck from damage just in the amount of time one doesn't screw w/the deck. The results are 100% good. The copper allows for spreading out in the groove a little more favorible if the grooves have been damaged & or irreglarities at the site as well.
la360
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Post by la360 »

I am not over fussed if I have to machine out the o ring groove, as I have to order custom length Aluminium rods anyway. I will just machine them 0.020"-0.030" shorter if need be.
AL...
Trev
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Hi

Post by Trev »

Thanks John

I might remove the stainless next time and use copper as you suggested.

Good luck with the rebuild LA
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