Headgasket thickness question?

[Oldmactech]

Got my cylinder head back from machine shop shaved .011. I was told I need a gasket .2 thickness. Is that normal, extreme or a average?

Good source for a quality gasket that SPEC.

Thanks.

[oldskewel]

What units are those numbers?

A standard head gasket on the M54B30 is 0.7 mm thick. That's what comes as the original HG. I had my head surfaced to fix slight warping, that was causing the same problem you seemed to have. After that, I was told that he did not need to remove too much, and that I could replace with a 0.7 mm HG, and that's what I did. Working fine like that.

As far as I know, the only other option is 1.0 mm. I never saw anything bigger than that, although I was not looking for it. I can believe that at some point, a gasket can be too big. For example milling off 1 cm and replacing it with a 1 cm thick gasket would definitely not work, of course. I don't know what the cutoff is, but maybe 1.0 mm is the max for a good reason.

[Oldmactech]

The .011 is in inches. . Which is .279 mm

I see lots of 1.0 for sale, nothing taller.

[oldskewel]

Originally Posted by Oldmactech

The .011 is in inches. . Which is .279 mm

I see lots of 1.0 for sale, nothing taller.

OK, so if you started at 0.7 mm and he milled off 0.279 mm, then 0.979 mm would be the new ideal thickness, so the 1 mm HG would be a fine choice and is readily available.

But what's the .2?
"I was told I need a gasket .2 thickness."

I'd check to see what he meant by that. 0.2 inches is is 5.08 mm, which is not going to work. Maybe he meant "0.2 mm thicker" ???

These HGs come size in metric - 0.7 or 1.0. His milling machine is probably in inches ???

[andrewwynn]

It would only be for curiosity sake to define what was the miscommunication, there are usually two common gaskets, one if no machining was done and one of there was machining done. As the math above shows, the thicker one looks like about perfect.

The point in the thicker gasket is to not throw off the geometry of the inside of the cylinder: eg without it you will increase your compression and bring the pistons closer to the valves.

[bcredliner]

Originally Posted by andrewwynn

It would only be for curiosity sake to define what was the miscommunication, there are usually two common gaskets, one if no machining was done and one of there was machining done. As the math above shows, the thicker one looks like about perfect.

The point in the thicker gasket is to not throw off the geometry of the inside of the cylinder: eg without it you will increase your compression and bring the pistons closer to the valves.

[Oldmactech]

Thanks.

I guess I didn’t ask the correct question. He wrote .011 on the side of the head as what he removed. Measured in inches. I ask him what gasket to get and sorta vaguely said .2. Didn’t know enough to ask for explanation, figured it was a common thickness.


I called him back later and he said he doesn’t do the gaskets that the shops he deals with know what to use based on his measurement.

I gthe 1mm will likely have to do.

[oldskewel]

Sounds good. So just ignore the ".2"

A 1 mm thick gasket will be perfect.

BTW, when my head was machined (and the only problem I had was warpage), not enough came off to warrant going up to the 1 mm thickness, according to the machinist.

[Oldmactech]

Thanks. Ordered timeserts and will be ordering a gasket.