Honda-Tech - Honda Forum Discussion

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- Engine Machining & Assembly (https://honda-tech.com/forums/engine-machining-assembly-164/)

- - Head Gasket Bore (https://honda-tech.com/forums/engine-machining-assembly-164/head-gasket-bore-3332516/)

Head Gasket Bore

I have a stock b18c that is bored to 82mm. I was curious as to whether the OEM head gasket would work with this bore size.

Re: Head Gasket Bore

Quote:

Originally Posted by racerguy (Post 51829329)

I have a stock b18c that is bored to 82mm. I was curious as to whether the OEM head gasket would work with this bore size.

i wouldn’t think you would want a gasket to over hang into the cylinder, I would recommend getting a 82mm gasket

Re: Head Gasket Bore

You don't want too much overhang because it can act like a hot spot and cause preignition and detonation under some circumstances. With that said, being only 1mm over on a stock engine, you should be fine.

Re: Head Gasket Bore

I'm pretty sure that the OEM gasket is designed to work up to 82MM bore. So that the dealer can service the engine up to 82MM.

Re: Head Gasket Bore

Quote:

Originally Posted by civic-steve-94 (Post 51829817)

I'm pretty sure that the OEM gasket is designed to work up to 82MM bore. So that the dealer can service the engine up to 82MM.

The factory "B" series head gasket is .50mm larger than the stock bore. Specifically, B16A, B18A/B, and B18C1/5 OEM head gaskets are bored at 81.5mm and the B20B/Z OEM head gaskets are bored at 84.5mm.

It is never a good idea to have gasket material hanging out into the combustion chamber... meaning the block bore is LARGER than the gasket cylinder opening. The offending material gets red hot during operation and promotes detonation/pre-ignition and increases the chances of blowing a head gasket. It is always best to use a gasket that is the same size as the cylinder bore or slightly larger... as in .5mm larger at most.