Metal Head Gasket

[Devils_Advocate21]

Do you recommend that this should be under the FI quick reference guide so other users that may want to follow these things are able to easily find out the answer?

MODS?

[Duncan]

why on earth would all japanese gaskets be good and all local gaskets be bad? is there some magic in gasket manufacturing in Japan that locals don't know?

[Cubes]

Carl,

I believe it comes down to the competency of who's fitting the headgasket, I had my block decked as it was required to achieve the comp ratio I was after, the head was checked for straightness and it was apparently perfect so it was left as is.

I've had my cometic headgasket on for close to 2yrs and 45,000km's without a problem. Bl4ck32 has had his on for the same duration but slightly less kays and a heap of other blokes here in AUS run cometics without issues.

Saying that the bloke who machined and assembled out motors used cometic gaskets on everything, so clearly he knows the gasket. I too did a little search prior to approving the use of cometic headgasket and found lots of ppls had leaks etc.. He told me not to worry he knows what he is doing and never has had a problem using a cometic gasket.

Its most likely similiar as to having your engine builder recommend using a forged piston that he is familiar with then insisting he use forged piston on a brand he has no experience with... I do remember one case where one person did this and ended having a motor fail within a few hundred km's as the builder wasn't aware of a little pin securing quirk the pistons had.

I've attached a few pics of the surface finish.

[carl h]

agreed...the head and block have to be absolutely perfect for it to seal right with a cometic if it isnt then it wont seal worth a damn, mainly because since its mls composition it doesnt have the ability to fill small imperfections in the head and the block like the stocker.

i have heard of people spraying the cometic gasket, head, and block with copper spray a gasket to aid in sealing for those people who's head and block arnt quite up to snuff...

glad to hear your engine builder knows what to do, some do some dont.

I believe it comes down to the competency of who's fitting the headgasket, I had my block decked as it was required to achieve the comp ratio I was after, the head was checked for straightness and it was apparently perfect so it was left as is.

Saying that the bloke who machined and assembled out motors used cometic gaskets on everything, so clearly he knows the gasket. I too did a little search prior to approving the use of cometic headgasket and found lots of ppls had leaks etc.. He told me not to worry he knows what he is doing and never has had a problem using a cometic gasket.

[Col-GTSX]

Yeah i used copper spray last time i did my head gasket in the black skyline i had...

Its not cheap and was hard to find... (Only because most people had no idea what i was talking about when calling shops)

I have always used a little copper spray when doing a head gasket... I just its just what i was taught at tafe...

[Cubes]

On the cometics its apparently bad to use any spray.. Its what the person who assembled my motor told me.

The cometic I ran had a rubber type covering over the top and bottom layer...

[r33_racer]

We used an ACL mls headgasket for the rb30det....no problems at all..though the head and block were decked/faced.

[proengines]

There is absolutely no problem with the Cometic gaskets. Like any MLS gasket, the surface finish needs to be spot on, any decent machine shop should be able to give you a suitable finish. Don't use any goo or spray on them, they have a viton coating which works better than any spray. A lot of the sprays will stop the viton sealing properly against the block and head.

No MLS gasket will seal properly if the block or head is not flat. You can file any high spots off if you are fitting the gasket in the car, use a straight edge and a feeler gauge to check. Most blocks will pull up slightly around the head bolt holes which you will need to rectify before fitting the gasket.

I've used cometic gaskets on engines making over 150Kw per cylinder without the gasket failing. I've also used one on an SR20 which detonated so badly it ate away the quench pads on the head and the alloy at the top of the bore but the gasket did not leak or even look damaged.

The ACL race series MLS gasket is made by Cometic, they won't put their name on anything they dont think is top of the line.

[discopotato03]

The story I've always had is that its best to have a fresh working surface on the deck of the head . I've almost always had the usual 3 thou taken off particularly if things got a bit hot . I believe it works because head gasket fire rings will compress slightly the head material when bolted down . When its time to replace the gasket there is a much better chance of it sealing if its flat . Should mention I used Nismo gaskets on the L and genuine gaskets on the FJ20 - never had any problems .

When the RB30 gets built I'm thinking of trying the brass rings with the fire rings removed from which ever is the apropriate gasket though this obviously would be difficult to do to an engine in situ . Don't know , depends on what sort of cylinder pressures its likely to run . I should do a search and see if Cometic or Nismo do a gasket to suit the 87.5 bore I want to run . If I get the CR/cams/turbo to my liking it probably won't need much more than mild boost to make the torque I want so maybe just a good conventional one will do .

Cheers A .

PS : A fello I used to know was using the brass ring system on FJ20's that were running 30+ lbs boost and cranking out around 720 Hp on Dave Handleys engine dyno without problems . Definatly super duty system ! This was a few years back though , don't know where he's up to now .

[Devils_Advocate21]

Ahh cheers guys this is some good responses which are coming through, and decided on what i will be doing

[Wilkie]

anyone with anything?

I'm not sure if im in the right thread or what not but I have some issues with my R33 skyline with all the mods I have I am only putting 175.6 RWKW running on 8 psi boost, just spent over 2 thousand on it at a place i wish not to mention... never going there ever again. But here is a list

740 cc injectors

highflow turbo

greddy front mount

2.5" piping

bosch o44 fuel pump

power fc ecu

dump pipe

3" front pipe

3" from cat back

exhaust

Any ideas on WTF is going on would be appreciated as im getting seriously frustrated.

[Keeper]

At what horsepower should you look at a metal gasket? Or is it just a taken that if you rebuild or head off you should???

[Humbla]

A couple of years back valve guides went on my 33,head reco,so i thought i'll get a better head gas,got a acl tripple layer fitted,mechanic said to only run water for 1000 kays as they tend to leak if you put coolent in strait away,did this and put top coolent in then no leaks all good.