head gasket specs

[lou schmouder]

I have a 1995 block with 100MM crank. .20 pistons and a 1999 head. what head gasket do I need to use???

 

[brass420]

You do not "need to use" any particular head gasket unless you have a 1995 2.4 block, which I can't tell by your post. And even then you have options.

There are a quite a few variables including what block you have, what compression ratio you want, MLS or factory organic, how much you want to spend, how much boost you want to run, what kind of head studs are you going to use, etc., etc..

 

[Tyeler18]

You do not "need to use" any particular head gasket unless you have a 1995 2.4 block, which I can't tell by your post. And even then you have options.

There are a quite a few variables including what block you have, what compression ratio you want, MLS or factory organic, how much you want to spend, how much boost you want to run, what kind of head studs are you going to use, etc., etc..

He's asking size. If I remember right STD bore is 85.5mm? Someone correct me if I'm wrong, but you're bored out.

 

[dsmtunz]

85mm should be good man ^^ this dude is right

 

[talondave]

STD bore is 85mm and .20 over bore is 85.5mm, so when you go to order the head gasket, just tell them you need a 7bolt head gasket with a .20 over bore, they will know what to send you!

I'm pretty sure the 6bolt, and 7bolt head gaskets are the same, but not 100% sure, cause I have never searched it...

 

[gofer]

Headgasket bore sizes are as follows...

Standard - 85.5mm
.020" over - 86mm
.040" over - 87mm​

I hope you didn't actually get .20" over pistons.

 

[nitrouskris]

Headgasket bore sizes are as follows...

Standard - 85.5mm
.020" over - 86mm
.040" over - 87mm​

I hope you didn't actually get .20" over pistons.

I have a 1995 block with 100MM crank. .20 pistons and a 1999 head. what head gasket do I need to use???

85.5mm

 

[gofer]

Are you ensuing that I'm incorrect here or do you just feel like slamming your head into the wall? The OP is asking for the correct bore size of the headgasket with .020" pistons so he needs a 86mm HG. Sorry...

Like I said, the standard headgasket is 85.5mm so if you went .020" over then you need a 86mm. If you don't believe me try ordering one from STM and select the correct HG from the drop down.

STM: Cometic HG
​

I think this is easily confused because the standard piston bore is 85mm, so when you go .020" over pistons they become 85.5mm, is this why I keep seeing 85.5mm?

To the OP, if you're shopping for a HG and you're running .020" pistons then you want an 86mm headgasket.

 

[Calan]

Like I said, the standard headgasket is 85.5mm so if you went .020" over then you need a 86mm.

That's pretty confusing. Most of the vendors I've seen refer to them based on the cylinder bore.

Here is the same gasket at extremepsi...notice they list the same sizes, but refer to the bore size:

EXTREME PSI : Your #1 Source for In Stock Performance Parts

Here is another example at MAPerformance. Notice they reference the smallest sized gasket as 'Bore - 85.5mm (.020" over)' :

http://www.maperformance.com/cometic-multi-layer-steel-head-gasket-dsm.html

I've always bought them based off the bore size and never had an issue. (I'm running the 86mm version of that exact gasket on my .040" bore). It's a bit strange that neither one offer the stock bore size for that gasket though, if that's really what they are referencing.

On MAP's page, it says this:

In the event that the 85.5mm gasket is not available we will send out the 86mm gasket in its place. There are no adverse affects from running a larger bore gasket. We have confirmed this by running the 86mm bore gasket on both stock and .020" overbore engines

To me that implies that they consider the 86mm gasket to be for .040" bores, but it will work for both stock and .020" bores as well.

EDIT:

I just measured the ID of the fire rings on a brand new Cometic 86mm gasket (PN#C4234-066), and they measure 86.35mm.

 

[gofer]

So which ones correct, STM clearly says standard bore is 85.5 and .020" is 86mm? Here is another example so I don't think its a typo just for the Cometic HG.

STM:Head Gasket Kit

Now that I read through the MAPerformance website, really it doesn't matter whether he runs the 85.5mm or 86mm HG anyway. The quote below is pulled directly from MAP's website...

*In the event that the 85.5mm gasket is not available we will send out the 86mm gasket in its place. There are no adverse affects from running a larger bore gasket. We have confirmed this by running the 86mm bore gasket on both stock and .020" overbore engines.

 

[Calan]

So which ones correct, STM clearly says standard bore is 85.5 and .020" is 86mm? Here is another example so I don't think its a typo just for the Cometic HG.

STM:Head Gasket Kit

Now that I read through the MAPerformance website, really it doesn't matter whether he runs the 85.5mm or 86mm HG anyway. The quote below is pulled directly from MAP's website...

I beat you to that quote. Did you even read my post? (Just kidding..I was ninja editing. )

You're right though...it won't matter too much. FWIW, the Fel-Pro Permatorque MLS only comes in one size which is 87mm.

Just for giggles, I went out and measured the old Cometic C4234 that I pulled off last week, and it measures about 86.20mm on average. So that means I saw about .15mm of ID lost to crush, which still left enough room for my .040" over-bore.

I would probably recommend either the 85.5mm or the 86mm for a .020" over-bored engine.

 

[gofer]

... I beat you to that quote. Did you even read my post?

...not after you ninja edited it!

The SCE Titan HG's that FFWD only come in two sizes "small" bore and "big" bore. The small size bore is recommended on engines between 85mm-85.75mm and the big bore is for engines between 85.75mm and 87mm.

 

[Calan]

...not after you ninja edited it!

Yeah... I'm pretty bad about that.

I was actually ninja editing my last post to explain that I was ninja editing, while you were accusing me of ninja editing in the above post.

 

[talondave]

I thought I was stupid, and was giving bad information, on my post!
Was looking at JE pistons and they say .020 bore is 85.50mm, and .040 over is 86.00mm...
I also have a .020 over bore on my motor, and I'm running a 86mm head gasket!

 

[Calan]

Was looking at JE pistons and they say .020 bore is 85.50mm, and .040 over is 86.00mm...

Fixed.

.040" = approximately 1mm

 

[talondave]

Fixed.

.040" = approximately 1mm

Yes yes, kept forgeting the first 0..

 

[Diamond Star Werks]

Came across searching for some info on something. Found this could be confusing to anyone that doesn't know better since your all unsure or at least were at this time. Stock bore is 85mm, .020" 85.5mm, .040" 86mm, .060" 86.5mm(standard bore for a 4g64), .080" 87mm.