Head gasket

[SupraTuned]

Ok, for some reason nobody likes to respond to any of my questions, but thats ok. Anyway, I am beginning to become very very angry at the fact that none of the after market metal head gasket companies make a head gasket in the stock 7mgte bore. My car only has 38,000 miles on it and I have absolutely no intention of boring it out just because. I have been looking for a variable array of thicknesses in metal head gaskets and have been unsuccessful, since I am having my head skimmed a touch. Where can I find one?

[bgrieger]

stock is roughly 1.2mm thick. Your machinist will tell you how much they removed. Add that to the stock thickness and away you go.

If you are looking at bore, how about measure the stock gasket bore and match it...I havent' had one apart in a long time and cant remember off the top of my head what it is. Since you have it apart, I'm sure it won't take long to find out.

[Jeeves]

You are also misinformed that the bore of the cylinder and the HG bore need to match. They don't.

[SupraTuned]

Well thats strange, because I know that altering the bore of the head gasket by 1 mm or more will cause your compression to go the way you don't want it to.

[Jeeves]

Originally Posted by SupraTuned

...will cause your compression to go the way you don't want it to.

Which is what way? On a boosted engine you sure don't want to raise compression. That'll increase your chances for detonation. Even then, you're talking very minor amounts of compression change.

[bgrieger]

regardless, as Jeeves said already, the headgasket is still almost always larger in bore diameter than the bore of the cylinder. It is called the quench area and it needs to exist. There is a huge physics and chemistry lesson in it and while I've read it I still have trouble understanding it well, but I do know that since every engine designs it in, I'll keep running with it until a very large brain tells me otherwise. Anyhow, I chose a good builder and rely on him to let me know what I need and why for these measurements...I ask questions where I may have heard or read something, but he's always happy to follow up or let me know what I may have missed...and that is why I pay him.

Anyhow, I've never heard of any engine without an overbore needing a larger bore gasket. I'd confirm it with your machinist as well, but since they will tell you how much they removed to select the gasket thickness I'm sure they can help here.