Cylinder base gasket

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Jul 16, 2020 | 08:34 AM

#11

Adam76

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From: out there

Quote:

Originally Posted by Hillsidecycle.com

We glass bead that paper gasket off, then into the lathe fixture to establish flat/perpendicular to the bore C/L.
.005" is a typical cut.
Scott

Quote:

Originally Posted by prodrag1320

if it is the cometic steel gasket,it should come right off,if its a paper gasket,bead blast it off (or machine it like stated earlier)

Thanks Scott and Kirby,
I'm thinking it may be the factory gasket because there were signs of light brown silicon used the inside of the engine case and even a bit stuck to one of the rods. Did they do that at the factory?

Anyways, I've taken it to the machine shop to be done. They are blasting it off.
Cheers.

** Also want to pick your very knowledge brains on how to factor in new base gasket thickness when calculating zero deck height. Do I place the new base gasket in place, torque cylinder down fully? To check deck height? Or do I use a generalised assumption of how thick or thin the gasket will be once compressed?
Hope that makes sense.

Last edited by Adam76; Jul 16, 2020 at 08:36 AM.

Jul 16, 2020 | 08:35 AM

#12

Max Headflow

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From: poway

Yeah, It may be stainless steel and not aluminum. I generally set up without the base gasket then gust add it as most cometics have embossed sections that crush. Some have gotten away with reusing crushed gaskets but I've had leaks from even good cometic gaskets.

Jul 16, 2020 | 08:38 AM

#13

Adam76

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From: out there

Quote:

Originally Posted by Max Headflow

thanks max, so generally how thick would you say a used / compressed base Cometic gasket would be?

Jul 16, 2020 | 09:09 AM

#14

Max Headflow

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From: poway

Quote:

Originally Posted by Adam76

thanks max, so generally how thick would you say a used / compressed base Cometic gasket would be?

Cometic make all kinds of thickness of base gaskets. As to to how much they compress, I'd say only 1 or 2 thou from new measured at the non embossed(thinnest) part.

Jul 16, 2020 | 03:47 PM

#15

60Gunner

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From: Dubuque, IA

I've reused the cometic mls head and base gaskets 3 times and never had a leak.

Jul 17, 2020 | 05:55 AM

#16

prodrag1320

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From: deland,florida

if your going back to the OEM gaskets,you should have measured for deck hieght before having the gasket removed

Jul 17, 2020 | 06:27 AM

#17

Adam76

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From: out there

Quote:

Originally Posted by prodrag1320

if your going back to the OEM gaskets,you should have measured for deck hieght before having the gasket removed

no, not going back to oem - using a new Cometic base gasket (see a few posts back). Just wondering how to calculate an accurate deck height without ruining the new gasket?
Thanks.

Jul 17, 2020 | 06:29 AM

#18

Adam76

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From: out there

Quote:

Originally Posted by Max Headflow

Cometic make all kinds of thickness of base gaskets. As to to how much they compress, I'd say only 1 or 2 thou from new measured at the non embossed(thinnest) part.

ok thanks, that sounds easy enough.

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Aug 13, 2020 | 07:42 AM

#19

Adam76

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From: out there

Quote:

Originally Posted by Hillsidecycle.com

We glass bead that paper gasket off, then into the lathe fixture to establish flat/perpendicular to the bore C/L.
.005" is a typical cut.
Scott

Thanks Scott, now that I've cut .005" of the bases -- I want to install cylinders to check piston deck height with new pistons..... How do I do this without crushing the new Cometic .020" base gaskets when torquing down the cylinders?
Thanks for your advice.

Aug 13, 2020 | 04:44 PM

#20

60Gunner

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Joined: Sep 2017

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From: Dubuque, IA

Quote:

Originally Posted by Adam76

Dont worry about crushing them. You can reuse them repeatedly after til the black starts to wear off.
Made me cringe reading how some removed that paper gasket.

Last edited by 60Gunner; Aug 13, 2020 at 04:48 PM.