Cometic issues!

[turbovanman²]

As some of you know, the last time out, I was pushing out water. I just took the head off and well, its easy to see where. #3 cylinder was the worst, you can see the dark area around the coolant holes, #2 was almost there. Also, between 2 and 3 the area was dark. I forgot to use spray gasket but I can't see how that would stop this from happening. I am using the thinnest Cometic. Should I just go back to regular gaskets or if I reuse this with some copper spray, will it seal?

[Juggy]

im runnin a copper intake/exhaust manny gasket

i happened to ask the machinist if i should use any sealer and he said YES.
gave me a bottle of sealer, thats non hardening tacky finish. its got the cotton swab ball so i just goop it on BOTH sides of the mating surfaces and let it cure for 5 mins then assemble...dont know what cometic recommends to use tho...

arent u using ARP studs?? what do u have the head torqued down too???? i blew out all 4 cylinders on the headgasket on only 18 psi and 70-75fpt on the studs....

[slasky]

I have reused my cometic 4 or 5 times. I just clean it us and use copper spray and I have never had a problem with it.

[BadAssPerformance]

Head Gasket in a can...

http://www.badassperformance.com/mrides/z/04_specs/permatex_hgiac.jpg

[bakes]

If you are lifting the head there not much you can do but find some way to improve clamping.
I cant remember if the block and head have to be machined with a special finish to run Cometic Gaskets to there full potential.
What about o-ring the block?

[rx2mazda]

+1 on the permatex

still using a old 3 layer cometic on my R/T with that spray.

[turbovanman²]

ARP studs torqued to 85 ft/lbs.

Guess I'll clean it up, take it apart and spray all sides and see what happens.

[Pat]

Are you sure everything is flat? Are you detonating?

[88_pacifica]

How smooth is the block and head? Cometic's tolerances are much lower than a traditional HG. It must be mirror smooth...

http://www.cometic.com/faq.aspx

"What surface finish is required to us an MLS head gasket?

A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design. "

[contraption22]

I've never had my block or head surfaced in a special way to use the cometic, but I always use copper spray liberally.

I think you may need a bit more fastener torque too, but im not sure.

[black86glhs]

Spray it and clamp it down to 90 ft lbs. You should be ok as long as there is no perforation of the cometic around the edges.

[cordes]

At the levels you are at slight detonation will lift the head. I'm not getting down on you at all, but you just don't have the margin for error which was there a couple years ago. I'm sure you know that already though.

[turbovanman²]

Are you sure everything is flat? Are you detonating?

Yep, head was fresh when I put it on and block has been trued and checked.


I've never had my block or head surfaced in a special way to use the cometic, but I always use copper spray liberally.

I think you may need a bit more fastener torque too, but im not sure.

Ack, 85 seems pretty damn tight, so I'll guess I'll spray the crap out of it and torque higher.


At the levels you are at slight detonation will lift the head. I'm not getting down on you at all, but you just don't have the margin for error which was there a couple years ago. I'm sure you know that already though.

Yeah, I know, :o

I had detonation issues at the track but not on the street, weird.

[black86glhs]

Ack, 85 seems pretty damn tight, so I'll guess I'll spray the crap out of it and torque higher.I think I said that.:confused2:

[Ondonti]

Simon, i would still take a thin feeler gauge and steel ruler to both surfaces.

I have reused my cometics, but not after pushing coolant.

IMO, cometics have a really weak fire ring. Thats why people who have MLS gaskets stock don't like them. Usually factory is better. Cometic just has some crappy embossment on the outside layers, no actual increase in material thickness to put extra clamp loads around the cylinder.

I would try a receiver groove and steel wire that protrudes .004" or so (any more and it probably won't seal the coolant passages) Or try copper wire that protrudes slightly more.
MLS + O ring was all the rage in the DSM world but it seems many doing what I just did, O ring a composite gasket.

If you leave the Knock sensor plugged in, you might be okay with nothing added to your cometic setup.

[cordes]

There's no way Simon should need to O-ring it given the power level he's at.

[Ondonti]

Cometics are not as good as most factory MLS gaskets. So its not really a matter of "should"

He is running a 2.5L TIII so I don't think anyone can claim "should" based on experience. Since there is no experience.
I would love to see simon hit the dyno so I can see what his powerband looks like with the 2.5L and his ported heads and stock? cams.

[bakes]

There's no way Simon should need to O-ring it given the power level he's at.

I think the power levels are a little higher than you think . this is a full weight van so his motor has to work harder than say a l body

[cordes]

Cometics are not as good as most factory MLS gaskets. So its not really a matter of "should"

He is running a 2.5L TIII so I don't think anyone can claim "should" based on experience. Since there is no experience.
I would love to see simon hit the dyno so I can see what his powerband looks like with the 2.5L and his ported heads and stock? cams.

You have a very valid point there. I'm basing my statements off of other high HP TIIIs, but the 2.5 could be making a difference, and certainly all the other work he has done is making a difference.


I think the power levels are a little higher than you think . this is a full weight van so his motor has to work harder than say a l body

As far as I am aware people have made more power with the TIII (albeit 2.2s) that what Simon is currently making. Larry made over 400WHP with a pretty much stock long block if I'm not mistaken.

[rx2mazda]

You have a very valid point there. I'm basing my statements off of other high HP TIIIs, but the 2.5 could be making a difference, and certainly all the other work he has done is making a difference.



As far as I am aware people have made more power with the TIII (albeit 2.2s) that what Simon is currently making. Larry made over 400WHP with a pretty much stock long block if I'm not mistaken.

>500whp for Larry. I think 535 on spray and stock block with cometic.

[Ondonti]

You have a very valid point there. I'm basing my statements off of other high HP TIIIs, but the 2.5 could be making a difference, and certainly all the other work he has done is making a difference.



As far as I am aware people have made more power with the TIII (albeit 2.2s) that what Simon is currently making. Larry made over 400WHP with a pretty much stock long block if I'm not mistaken.

And we also know simon's propensity to run too much timing, which is even more dangerous on a 2.5 8v so who knows on a TIII 2.5.

Maybe if he suffers more serious failure he will back off the timing :)

[turbovanman²]

Maybe if he suffers more serious failure he will back off the timing :)

Suffers a serious failure, have you seen my carnage threads???? :confused:


And we also know simon's propensity to run too much timing, which is even more dangerous on a 2.5 8v so who knows on a TIII 2.5

I never had the ability to adjust my 8 valve cals so the timing was what Rob put into the cals.

[rx2mazda]

And we also know simon's propensity to run too much timing, which is even more dangerous on a 2.5 8v so who knows on a TIII 2.5.

Maybe if he suffers more serious failures again he will back off the timing :)

Fixed:D

[Aries_Turbo]

was the 85 ftlbs with oil on the threads or moly? if its just oil, id do at least 90. the paper that came with my studs said 80 with oil and 65 with their moly lobe. thats low imho though.

he is lifting the head with detonation cause he wont take the time to tune it till its totally right :)

"F-it, im going to the track, ill tune out all the knock later!!!!" ;)

brian

[cordes]

Suffers a serious failure, have you seen my carnage threads???? :confused:



I never had the ability to adjust my 8 valve cals so the timing was what Rob put into the cals.

I know it's been a while, but you have been know to write about adjusting the dist. back when. That was back when though. :thumb:

[turbovanman²]

I only ever ran 12 deg's on the TIII combo, 14 on the 8 valve, :D

Anyhow, took the cometic apart, cleaned it and used a can of copper spray, torqued to 95 ft/lbs, so if this doesn't fix it, nothing will, :o

[black86glhs]

I only ever ran 12 deg's on the TIII combo, 14 on the 8 valve, :D

Anyhow, took the cometic apart, cleaned it and used a can of copper spray, torqued to 95 ft/lbs, so if this doesn't fix it, nothing will, :oAnd it is finally back together!!!:amen:
Have it running yet?

[turbovanman²]

And it is finally back together!!!:amen:
Have it running yet?

No, not yet, I need to fix up my crankcase vent system first before putting the intake back on and still waiting for my tranny parts, :(