Head gasket for 4agte

[BoostBoy]

Hey everyone. I am in the process of building my gen3 100kw 4age motor for a turbo conversion.

The block has been O-ringed and I was wondering how this will affect my choice for a head gasket. The motor will hopefully be able to make 200kw atw, so my first choice was to get a Cometic metal head gasket, but I have heard that if the block is O-ringed I will only be able to get a copper head gasket? Is this true and if so, why is this the case?

I should also mention that the block has been bored to fit 82mm oversized pistons...will this also affect my choice of head gasket, or will I be able to modify it?

While I'm on the topic...my block needed to be decked ***EDIT: by about .2 of a mm, because of corrosion. There is a chance that the pistons will now slightly sit above the bore. I know I can machine the pistons, but would it make sense just to get a thicker head gasket?

[fixeruperer]

i had o-ringed block but got them machined off good copper gaskets are hard to find and to get them to seal can be a problem.
you cant use any metal head gasket becuase it wont crush on o-rings and if you cant find copper just get a factory "toyota 4agze" head gasket

ive just gone no o-rings with cometic or felpro head gasket


id check ya piston hight, your compression would have raised aswell.

[Big T]

As said, a metal hg has its own crush areas so don't require o-ringing to seal.

You can see the raised areas on this hg



Generally, aftermarket hgs are slightly oversized to accommodate over-boring. The above one has an 82mm bore.
You might also want to consider HKS. They come in different thicknesses as well.

Eddie.

[Big T]

I just re-read and it says you need 80 thou off the block as well? That's a full 2mm off and i'm doubting you can get an off the shelf hg that's 3mm (minimum) thick. There was somewhere that made custom gaskets to any thickness you needed.... can't remember the name of it. Somewhere in Vic i think. I'll see if i can dig up the name.

Eddie.

[oldcorollas]

80 thou is a fair bit.... perhaps it's time to look for a new block instead?
as well as pistons almost definitely sitting proud of the block by a long way (and needing a very thick headgasket so they don't HIT THE HEAD!!!), you may have timing belt tension issues as well... 2mm is a lot!!

[Big T]

Found it.... Ridgecrest Engineering. They specialise in copper hgs.

And Oldcorollas is right... the best option would be to source another better condition block.

Eddie.

[30psi 4agte]

BigT : what brand is that HG and how thick is it?
Is it a cometic

[Rallystanza]

With the 4AGTE i have been building for oh so long now...I have in the end decided to go for a standard thickness ~1mm Cometic Multi layer steel head gasket. This has proved to be a popular and strong choice for many an American 4A turbo running up to 42psi of boost for over 2 years....

I had a thread where i discussed all the options and opinions on O ringing and how it would be unsuitable for a road car and that a MLS HG would clearly be the best option. Have a search for it under O-ring.

Oh and get a new block and engine builder too, 2mm is shit house of the top of the block.

Have a look here for all the 4A Cometic MLS HG's that are availiable.

http://www.paradiseracing.com/gaskets-toyota.htm

Jeremy

[Big T]

BigT : what brand is that HG and how thick is it?
Is it a cometic

Not a cometic one. It's a HKS 1.6mm bead type. I got it for just under $180 which i thought was pretty cheap.

Eddie.

[BoostBoy]

I'm an idiot!! It wasn't 80 thou off the block...I was sleepy when I typed this.

I can't remember how much exactly...it was something like .2 of a mm....but in any case a very small amount.

It would be a shame to machine the rings off after getting it all done...I would like to keep them and work around it if possible, but I guess if it becomes too much of a headache then I might have to.

[fixeruperer]

yeh i thought that too, then i machined them off .
if u have orings go copper and only copper.

[LeeRoy]

You prob mean 0.02, which is more likely what they would take off and around what one pass removes. Still thats like the hair on a bee's dick.
- LeeRoy

[cri_ag]

mate i know the general opinion on here is not to use a standard type gasket with fire rings on an o-ringed block and that you have to use a copper gasket. But ive been told from two different performanced based mechanics that is ok to do so and they have done it with succes before. my engine had o-rings and a standard type gasket when i pulled it down and there was no aparent signs of anything leaking or not sealing. perhaps you should have a chat with some performanced based workshops and see what they recomend.

[fixeruperer]

all standard headgaskets have a steel ring around the cylinder and this is not so good for the seal of the o-ring, the cheaper the gasket the worse the steel ring some arnt even round and the 2 middle rings in the center sometimes overlap.
i have had o-rings with 3 different gaskets 2 cheaper ones then the toyota one, the toyota one was the best (non copper) gasket looking at the o-ring indents on the gasket.
o-rings and copper is only combo there made for each other.

[BoostBoy]

But is a copper gasket going to be much weaker than a MLS gasket?