What does everyone use for a bottom end that has been overbored? Commetic is the only one I can find that makes these gaskets. On their site I can only find one for .040, I have a .020.

I believe Howell Automotive sells a bottom end gasket kit made to fit various size overbores ... .I'm not sure of their number, but their link is always in the banner up above ^^^^, check them out, you should find what you need.

I used a stock MLS headgasket w/ my .020" over bore. I don't think it matters at all. You'd just be changing the the combustion chamber volume at insignificant levels, not changing the shape of anything.

The 0.040" over gasket will work just fine with your 0.020" over bore.

I have a .020 overbore and the stock MLS gasket works good for me.

Originally posted by Scandelous
I have a .020 overbore and the stock MLS gasket works good for me.

Same here.

Wait. No it doesn't. Damn thing's been leaking for more than a year now, but that's got nothing to do with the bore. When you think about it, the average human hair is about four thousandths of an inch thick (0.004"). So yank a hair off your head, cut it in half, and then place those two strands of hair against the cylinder wall. Now throw them elsewhere and go get the OEM MLS from the dealer.

:wavy

Originally posted by DR1665
When you think about it, the average human hair is about four thousandths of an inch thick (0.004"). So yank a hair off your head, cut it in half, and then place those two strands of hair against the cylinder wall.

Brian, what comparison are you trying to make?

0.004" is not 0.040"

Originally posted by dougie2
Brian, what comparison are you trying to make? 0.004" is not 0.040"

Shit. I blame that damn statistics class I was forced to take in college. Messed me up good. ;)

What I was getting at was that we're talking thousandths of an inch, here. Given the average human hair being four thou, twenty thousandths is roughly the width of five hairs. In this instance, I don't see it as being such a great problem. Hell, if you're going forty over, I think you have bigger issues.

:shrug Sorry about the confusing math.

That's what I thought you were getting at... just want to make sure everyone here understands. The main thing is to make sure your head gasket's bore is larger than the actual cylinder bore. You can run a 0.040" over gasket with a stock bore diameter, but do not use a gasket if the diameter is less than the actual cylinder bore diameter. You DO NOT want gasket material in the cylinder bore. Most gaskets I've seen are 0.040" over.

There's nothing wrong with boring a block 0.040" over... it's just a pain to find out-the-shelf pistons for it. Easiest way is to call a manufacturer... they can usually manufacture a set fairly quick.

No worries, Doug. Good info in this thread. :thumbsup

you could also try overbore.com... they are buildin my motor right now, and they do a lot of 420a an 4g63 work, im sure they can create somethin for ya...