I spray both sides of gasket, motor and head with that stuff every time, no issues yet with MLS or even used 005 gasket.
I spray both sides of gasket, motor and head with that stuff every time, no issues yet with MLS or even used 005 gasket.
I used one the whole time I ran my built motor, and then ended up melting in on the dyno later on when I used it "for fun" on a test of using copper wire on an MLS gasket to make it work better. It did fail to seal which is why I took my built motor out and put a stock junkyard motor in to run 11's.
But as far as good MLS gaskets go, Cometic does not have a good fire ring around the cylinder compared to many OEM mls gaskets. Been shown that the mitsubishi OEM MLS clamps much harder then the Cometic when doing pressure film testing. The Cometic just has an embossed ring around the cylinder which is a complete joke. It adds no actual thickness to the gasket there.
Now, if you are looking for a fuze to make up for a bad tune, then sure, use a Cometic. If someone wants a fuse, use a crappy gasket IMO. I am now using Felpro composite gaskets because the 3.0 redesign gasket they did has a copper wire in the fire ring which clamps down and helps seal up when the deck tries to flex. It also puts up with changes a bit better.
Want to see a good headgasket, see what cosworth makes.
---------- Post added at 07:41 AM ---------- Previous post was at 07:38 AM ----------
At least this time I found what I was talking about.
This link is just a repost of the original information.
http://www.sfldrifters.com/forums/sh...ad.php?t=23323
Just because you guys are cursed with poor headgasket offerings doesn't make the Cometic good. You pay too much for what you get.
I would rather run a felpro on a 2.2 and learn to not detonate. People having so many headgasket issues turn into guys with engine problems when they seal things up.
I know the only reason the stock motor broke a ringland 2 summers ago was because I put steel rings in the composite headgasket when the headgaskets couldn't hold all that awesome detonation (20+ pounds of boost on n/a timine, 8.9:1, and running out of fuel). Oh yeah, those things sealed up. Oh no!
Look at the crap design of the cometic. It doesnt even seal at the edge of the bore so its promoting something to leak past eventually. Its like an O ring setup without the O ring.
I am not really sure which motor this is from. Might be Evo 4g63. DSM guys are often running composite OEM headgaskets instead of MLS
Last edited by Ondonti; 02-14-2011 at 10:01 AM.
Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56
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---------- Post added at 10:17 AM ---------- Previous post was at 10:17 AM ----------
http://www.cometic.com/files/CometicPhuzion.pdf
Gotta use the right cometic.
Its what these use. Those gas filled rings are the trick.
Ian Adams Function>Form 1990 shadow scrapped, too rusty:( 1991 Spirit R/T Scrapped, parts sold:( 1989 Turbo Caravan Daily beater with built-[I]ish [/I]engine slowly evolving into weekend turbo beater.
Melted motor? Copper wire? So how did the Cometic fail again?
By design, an MLS does not need excessive fire ring pressure as long as the deck and head are flat and torqued properly there is solid steel in the way of any pressure to get out.But as far as good MLS gaskets go, Cometic does not have a good fire ring around the cylinder compared to many OEM mls gaskets. Been shown that the mitsubishi OEM MLS clamps much harder then the Cometic when doing pressure film testing. The Cometic just has an embossed ring around the cylinder which is a complete joke. It adds no actual thickness to the gasket there.
Looking at the picture you posted, with the same clamping force, the Cometic has less area which means more pressure on the contacting surface, so in theory this should actually seal better.
True that a fiber gasket is a fuse, but any properly installed, with flat surfaces and proper torque, MLS gasket (Cometic or other) is typically not a fuse.Now, if you are looking for a fuze to make up for a bad tune, then sure, use a Cometic. If someone wants a fuse, use a crappy gasket IMO. I am now using Felpro composite gaskets because the 3.0 redesign gasket they did has a copper wire in the fire ring which clamps down and helps seal up when the deck tries to flex. It also puts up with changes a bit better.
JT
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LOL i've got a Cometic MLS gasket that i bought used. I've pulled the head on my car three times, using copper spray every time and pushing 18psi. So this gasket has been used 4 times and about 10k on it and not once have I had a problem. I've got ARP head studs and torque them to 85ft lbs.
I have to disagree, if an MLS behaves like you say, then its just as worthless as a copper headgasket with No oring.
The secret to sealing a headgasket is to concentrate pressure in a small area. The cometic results there might be a small line but not very much pressure is being exerted. Most good headgaskets exist because many cylinder heads suffer from deck flex. TD's get away with junk headgaskets because they probably have a very firm deck. You look into the world of Porshes and Pinto's and otheres, you will hear things about head pinning and cylinder head side O rings.
Cometic has repeatedly failed to make a headgasket for motors that actually suffer from cylinder head flex. Titan Headgaskets has failed at the same thing.
Piece of solid steel does no good when excessive cylinder pressure flexes the deck of your head. Having the clamping force farther away from the center of the bore also tends to expose cylinder pressure to weaker parts of the cylinder head.
Singing praises to Cometic is like singing praises to base model ARP head studs. Unless you order h11 or L19 tool steel bolts, ARP is worse then many non TTY OEM bolts.
Singing praises to a headgasket when a piece of refuse could seal your head is uncalled for.
A 2JZ supra is the same way. You never hear them talk about headgaskets. DSM guys, all the time. Porshe guys, all the time.
Just because its easy to seal your head doesn't make the headgasket good.
I think the paper headgaskets would seal fine if people were not constantly ignoring the fact that their ECU is constantly pulling timing because of knock. The OEM gasket for a 2.2/2.5 and the MP obviously don't appreciate being knocked on constantly. They start to fatigue and fail. That doesn't need to happen.
For me, Cometic sells an absolutely stupid 95mm headgasket, going back to the days when there was not even a 95mm motor to install in. So to go along with their poor clamping, the head seals like you have a 95mm bore when the OEM bore is 91.1
Imagine overboring your motor .150" and trying to seal the head. It makes a big difference.
I know you didn't post it but I don't understand what some fancy headgasket that is not sold for your vehicle really has to do with any of us. Titan sells a gas filled O ring headgasket that is a complete failure for anyone who actually needs a better headgasket.
If you want a ten thousand dollar headgasket, you have to pay 10,000 dollars. If you buy the 300 dollar version, it won't work.
Cometic is really detached from their market. They might make you a custom size headgasket, but they won't solve your head sealing issues if you have a real problem.
Now, if someone nukes multiple motors and is still using the same headgasket, I might say their are more important things to worry about then putting sealant on the headgasket. I would not install a cometic on a TD that has poor tuning control or an owner who is apt to ignore knock.
I have seen a cometic combined with ARP be completely worthless as the ARP just stretched (like they always do) when put under stress. A low buck OEM would have failed with much less risk to the motor.
Last edited by Ondonti; 02-20-2011 at 04:35 AM.
Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56
FTW! First year I had the Charger out with the 57 trim I blew the HG @ just over 25psi boost (never had a problem with the MP HG's up until then.)
Now, granted, the deck was original and pretty rough looking to boot, which is what brought me to use the copper spray. The rest is history, in over 5 years I've only changed the HG once from a 40+PSI boost spike 3 years ago. I will never Not use it again!
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Brent, you missed my original question. You have such hatred for Cometic, please explain exactly how your Cometic gasket failed on your vehicle?
What? The pink/white plot is binary so only shows that some minimum pressure is acheived to make it pink so there is no information showing if any are higher.
Pressure = Force / Area so with the same clamp force, a smaller contact area will produce a higher clamping pressure.
ALL head gaskets exist because of deck flex and thermal expansion, without those, we wouldnt need a HG.Most good headgaskets exist because many cylinder heads suffer from deck flex.
MLS gaskets were invented to help with more difficult sealing applications. But for each application, there are many variables from number of MLS layers to clamp force distribution, deck/head flatness, etc. etc.
Maybe you recall MP making O-Ring gaskets for TMs too? This is nothing new, but it was what was available in the 80's before MLS gaskets were common.TD's get away with junk headgaskets because they probably have a very firm deck. You look into the world of Porshes and Pinto's and otheres, you will hear things about head pinning and cylinder head side O rings.
Is this like your DSS hatred where you hate DSS but nobody esle makes better axles for our cars?Cometic has repeatedly failed to make a headgasket for motors that actually suffer from cylinder head flex. Titan Headgaskets has failed at the same thing.
The stronger steel material beind the fire ring bolsters it when fiber material cannot so it can prevent damage like this:Piece of solid steel does no good when excessive cylinder pressure flexes the deck of your head.
Nobody is saying that Cometic is the bestest headgasket in the world, just that in general they make good gaskets and work well on our TM's. I am noticing a trend tho with your ARP comment that you seem to hate all the companies that generally make good productsSinging praises to Cometic is like singing praises to base model ARP head studs. Unless you order h11 or L19 tool steel bolts, ARP is worse then many non TTY OEM bolts. Singing praises to a headgasket when a piece of refuse could seal your head is uncalled for.
What forum are you on? Do we care if a gasket works on a 2JZ or DSM?A 2JZ supra is the same way. You never hear them talk about headgaskets. DSM guys, all the time. Porshe guys, all the time.
Just because its easy to seal your head doesn't make the headgasket good.
Actually if a head gasket does seal my head easily, it does in fact make it a good head gasket in my book.
For 99% of TMers out there the stock MP fiber head gaskets are good. Hell, they are great for the given application. For those pushing more cylinder pressure, an MLS such as Cometic works better. That is all.
JT
SDAC Director
SDAC-Chicago President
JOIN SDAC and your local Chapter TODAY! - SUPPORT the CLUB that supports YOUR HOBBY!
87 Shelby Z - 10.50@141.66mph
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