HeadGaskets....OEM Vs All
Number one, the stock head gasket is a very stout piece and it is more forgiving then the Cometic, however that is not to be taken as an attack because cometic does build good head gaskets, stock is very, very good though.
Yes, an iron block will need to be decked. The high pressure gasses with "erode" the surface somewhat if it leaks for any amount ot time. You will probably not be able to see it, but your machinist will definatly be able to measure it....
Yes, an iron block will need to be decked. The high pressure gasses with "erode" the surface somewhat if it leaks for any amount ot time. You will probably not be able to see it, but your machinist will definatly be able to measure it....
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Originally Posted by EVO8LTW
No need to be like that. It was an honest question. Why do you need to check the deck on an iron block? Can detonation or head warpage deform the deck, or would it be a case where the block wasn't flat in the first place and that caused the gasket to blow?
On a side note I can't stress enough that the extra money spent on a HKS stopper is better insurance against a headgasket failure.
John
Originally Posted by joeycoates
Number one, the stock head gasket is a very stout piece and it is more forgiving then the Cometic, however that is not to be taken as an attack because cometic does build good head gaskets, stock is very, very good though.
Yes, an iron block will need to be decked. The high pressure gasses with "erode" the surface somewhat if it leaks for any amount ot time. You will probably not be able to see it, but your machinist will definatly be able to measure it....
Yes, an iron block will need to be decked. The high pressure gasses with "erode" the surface somewhat if it leaks for any amount ot time. You will probably not be able to see it, but your machinist will definatly be able to measure it....
Hit it on the nose. The stock head gaket is DAMN good for an OEM piece. If you want to usethe Cometic you will need to ensure thatthe head and the block are perfectly machined to ensure a perfect seal.
Originally Posted by badlooser
My cometic held 34psi the other day when testing with the br580 turbo kit and race gasthe other day.
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I have had all of the above a few others in the past few years.
I have since stayed with the Power Enterprise unit. 1.5 mm with head studs.
Best looking one so far. Quality gasket that has seen a tremendous amount of abuse from me.
I have since stayed with the Power Enterprise unit. 1.5 mm with head studs.
Best looking one so far. Quality gasket that has seen a tremendous amount of abuse from me.
One thing that noone seems to mention is that an OEM headgasket doesn't blow out because the gasket failed, it blows out because either the headbolts stretched a bit or because of detonation. There is no "better" than OEM. What matters is how it is held together. The material of the headgasket is made of stainless steel layers, just like Cometic, just like HKS, just like OEM. They may look different but they are all made of layered SS. The only way to get an even better seal than an OEM gasket would be o-ringing the block with copper wire.
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Joined: Sep 2004
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From: In my house
Originally Posted by 3240
I've been through three Cometic gaskets. Since then we've O-ringed the head.
Could it have been after you blew the first gasket, you didn't have a smooth enough surface to get a good seal, hence you contiued to blow gaskets?
Hopefully the o-ring on the head maybe some copper spray would help.
Originally Posted by propellerhead
I would second the Cometic but only if you're going to have the head and deck resurfaced. Also you've got to make sure you're dealing with a machine shop that is familiar and has FIRST HAND knowledge with the surface finish required for a good seal with the Cometic. The Cometic gasket requires a very smooth and very flat surface to seal properly as there is only .001" of Viton seal. Since the gasket is steel it will not compress at all so any surface imperfections could cause a coolant leak. Coolant leaks are the most common issues I've come across when researching the Cometic gasket.
Copper gasket spray is an inexpensive way of ensuring the head gasket won't leak coolant. I've read reports of great success spraying down the Cometic gasket with a couple coats of copper spray. The copper spray probably adds just enough compliance to the gasket surface to help prevent coolant leaks.
Copper gasket spray is an inexpensive way of ensuring the head gasket won't leak coolant. I've read reports of great success spraying down the Cometic gasket with a couple coats of copper spray. The copper spray probably adds just enough compliance to the gasket surface to help prevent coolant leaks.
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Joined: May 2004
Posts: 705
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From: Colorado
Originally Posted by Big Boost
See the quote below from propellerhead. I've been told the exact same thing by other engine builders about the Cometic.
Could it have been after you blew the first gasket, you didn't have a smooth enough surface to get a good seal, hence you contiued to blow gaskets?
Hopefully the o-ring on the head maybe some copper spray would help.
Could it have been after you blew the first gasket, you didn't have a smooth enough surface to get a good seal, hence you contiued to blow gaskets?
Hopefully the o-ring on the head maybe some copper spray would help.
What kind of gasket are you running with the o-ringed head? The stock MLS gasket or the Cometic? Based on ZERO experience on my behalf it looks like you could get away with an o-ring onthe OEM gasket. I'm not so sure with a Cometic.
Evolved Member
Joined: May 2004
Posts: 705
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From: Colorado
Originally Posted by propellerhead
What kind of gasket are you running with the o-ringed head? The stock MLS gasket or the Cometic? Based on ZERO experience on my behalf it looks like you could get away with an o-ring onthe OEM gasket. I'm not so sure with a Cometic.
Newbie
Joined: Mar 2005
Posts: 30
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From: Malaysia
hey guys,
its about time for me to change my metal head gasket too and i am considering aftermarket gasket like Tomei, HKS or even Cometic.
but i am confused about the sizes;
HKS - 1.0, 1.2, and 1.6
Tomei - 1.0, 1.2, 1.5 and 1.8
Cometic - not sure of available sizes
i was informed by my mech to skim the head (decked?) before replacing the gasket; but i am not sure which size to purchase?
care to help?
its about time for me to change my metal head gasket too and i am considering aftermarket gasket like Tomei, HKS or even Cometic.
but i am confused about the sizes;
HKS - 1.0, 1.2, and 1.6
Tomei - 1.0, 1.2, 1.5 and 1.8
Cometic - not sure of available sizes
i was informed by my mech to skim the head (decked?) before replacing the gasket; but i am not sure which size to purchase?
care to help?