Head Gasket ?

boostjunkie95 · Post by **boostjunkie95** » June 05, 2007

Ive seen quite a few builds where people are using oversized head gaskets, usually .5mm bigger then their bore. Are there any advantages in doing this? Just curious why they wouldnt use one that is the same size as the bore.

Secret Squirrel · Post by **Secret Squirrel** » June 05, 2007

using a bigger headgasket serves to purposes.

1. they had the block or head, or both machined, and the thicker HG is to compensate for that.

2. Changing HG size can vary compression ratio. So for example, a 1.2mm hg gave a 8.5:1 comp ratio and a .9mm HG gives a 8.2 compression ratio. **this is ficticious numbers**

SS

boostjunkie95 · Post by **boostjunkie95** » June 05, 2007

I didnt mean the head gasket thickness, I meant the size(diameter) of the cylinder bore on the gasket, example..... using a 76mm head gasket on a block with a 75.5mm bore.

Secret Squirrel · Post by **Secret Squirrel** » June 05, 2007

oh, ive never once heard anyone doing that....why would they?that would move the fire ring away from where it needs to be....s

GSR-Pimp · Post by **GSR-Pimp** » June 05, 2007

i dont think there is an advantage its probly not good also watch for leaks

miyagi · Post by **miyagi** » June 06, 2007

i've heard of it as well, but never did it. Always using the correct size ... never had a headgasket problem on any of my motahz