Cometic head gaskit

[neal]

Hey

Im about to put One in my 7M. What sort of surface preparation i need to consider.
Heads been machined, I have cleaned the block pretty much.

Any suggestions welcome. i have searched the net and also on other forums they reckon i should get the surface machined down to below 25 RA mirror finish. Is this really necessary.

Im also using ARP's.

cheers

[abently]

You really need a mirror finish on the block also..... Get a 50cm metal ruler and some feelers and check how flat the top of the block is. Someone else here will then be able to let you know if you'll be able to get away with it or not.

[The Real Roadrunner]

You really need a mirror finish on the block also..... Get a 50cm metal ruler and some feelers and check how flat the top of the block is. Someone else here will then be able to let you know if you'll be able to get away with it or not.

its pretty obvious that if the deck isn't flat the block should be machined and tunnel bored. Even if you dont get the tunnel bored then you should check it out because if the deck isnt level then chances are the crank tunnel isn't either

cheers
linden

[DeftAnesthetik]

not sure about the cometic but the copper head gaskets work best when sprayed with a few coats of high tack..... (spray on gasket maker if you dont know) permatex makes the high tack but you should be able to find other brands. just ask for spray on gasket at the autoshop they should know.

[jimmmayyy]

No need for sealant with a metal gasket. I had my block decked before I installed the Cometic... You're asking for trouble if it's not flat.

[abently]

Just clean the top of the block well and check the straightness. Cast Iron reacts different to aluminium when it comes to "over-heating" so it might actually be ok if you caught it early and shut it off.

[amichie]

The cometic head gasket is like a giant spring. A bit like the lid on a tin of paint.

If you have your gasket already you can see the raised section that seals around the bores and all the water and oil passages. If you find any spots that are low or corroded where this part sits on the block then you will need to have it decked.

Cometic is by far the most forgiving of all the metal head gaskets.

[DeftAnesthetik]

all good to know, ive never seen a cometic in person, all i knew is they were constructed by layering.

[neal]

abently: My original head was soft when i bought the car with rod knock. It (rod knock) wasn't that bad when i drove it home...

amichie: Its been neglected before, i do have corosion on my block, but right next to water gallery...only one spot..

Im planning on using a sharping stone to prep my block..smooth at first and the rough for the final at 45 degree angle.

A quick question can the cometic gaskits be reused.

cheers
neal

[jimmmayyy]

yep. 10char

[neal]

^Awsome stuff

[allencr]

My original head was soft

Im planning on using a sharping stone to prep my block..smooth at first and the rough for the final at 45 degree angle.

A quick question can the cometic gaskits be reused.

Soft?
45 degree?
Reused - Sure, no more or less then any other gasket can be reused.

[neal]

allencr : mate im just a little confused, you are asnwering my question or asking one.

[jeffro ra28]

MLS gaskets CAN be re-used. This also depends on the way its removed, and if there was any sealant used on it previously. Obviously, a good inspection of the black "tacky" surface needs to take place, if thats still well in tact. Iv re-used these gaskets up to 4 times without any ill affects at all.

Copper can be re-used even more times if it is prepared correctly and re-annealed.

Amichie- Im taking it you have personally used every make of MLS head gaskets???? to name a few, HKS, tomei, ACL, felpro, and all the OEM's?

[neal]

cheers for that jeff...i dont plan on using any sealant...