Copper head gaskets
Turbo Mini Forums

Cometic do a larger bore 998 gasket for those of us who have punched big holes in the block, great.

The drawback is that it is a pure copper gasket, which appears to have a few eccentricities in use...

Anyone got any direct experience of them, or copper head gaskets in general ?

Metric is for people who can't do fractions.

Gr4h4m has experience with those. I'm sure he will be along shortly

So far on Shaunas, the standard 998 copper headgasket has been fine, the cheapo fibrey one that was first fitted lasted about 6 months and failed through no fault of the engine.

What size bore is that on ?
I've got three on the bench to do - one at +.080", one at +.100" and one at 68mm.

The current +.080" engine which is being stripped for either a rebore at +.100" or 68mm will need one too, and it had an appetite for std 998 gaskets.

Metric is for people who can't do fractions.

Edited by Sprocket on 3rd Jan, 2017.

The Cometic copper gasket is indeed solid copper.

The copper Payen sandwiches don't seem to be as good as they used to be. I'm wondering if the varnish they're applying is gash.

Metric is for people who can't do fractions.

Yep I have a solid copper cometic gasket it never came with any instructions that were specific to the solid copper, just the standard ones.
I tried all sorts with it, gasket spray, well seal, two gaskets and the copper, all to no avail, but I will say that the car was running very badly at the time with the sc ecu so the failures are likely to be with that.
I went for a 940 head and plugged the afending waterways, and a 1275 cometic gasket at a thinkness that suited the cr I needed. I will never run anything else now.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I still have it if you want to try it.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I've got one on order from Burton Power (it worked out cheaper than having one shipped from the USA) and will try it before irreversibly blocking off and redrilling waterways in the block and head for a 1275 gasket.

Metric is for people who can't do fractions.

Shame you could of had this one cheap

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Are you still using a 998 head? Is that why you need a 998 gasket?

Is it boosted?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I've got a std 12G295 that's been enlarged to just over 29cc for the +.100" 1098 engine to get the compression ratio under control. It's not boosted luckily, or I'd need a gert big sandwich plate or one of the .080" Cometic gaskets...

The fallback plan is to use a 1275 gasket, but I really don't want to start blocking up and redrilling waterways unless I absolutely have to.

Having said that, if it was a matter of a moment to dry-deck a 998, I would.

Metric is for people who can't do fractions.

You need the head and block surface guiding to make sure they are 100% flat and level to use a copper head gasket.

What im told by local engine builder

To use the 1275 gasket you need to block a couple of water holes in the head. You can get away with leaving the block as it is, but there are a couple water ways that it's beneficial to block.

If it's not boosted, I reckon the solid copper gasket will be fine.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

That is on a bog standard 998 bore with a 12g295 fitted running 10psi, bog standard head studs, I didn't realise he meant a different gasket altogether, learn something new every day!

The gasket arrived this afternoon, and it is truly a thing of beauty - well, a lump of copper with holes in it.
Offering it up to the 68mm block, it feels like it will work quite nicely so ought to be fine on the others too.

The instructions that have come with it specify a flatness/finish standard and also recommend the use of Gasgacinch to help seal it, so I've ordered some of that as well.

Pictures once it's all underway.

Metric is for people who can't do fractions.

with the steel cometics your supposed to surface grind the block and head to get the correct finish, but I assume the copper is less fussy.