Just wondering if any of you guys have solved any "blowing the headgasket" problems by going with a .5mm over bored hg? I have an built 87mm h22a4 closed deck, 6266 running 26 psi in 4th, 1200cc injectors, s300 and boost-by-gear. The tune is spot-on...11.5's across the board and really conservative timing, so please no "you need to have it tuned" replies...its not the tune. It actually does perfect for months on end, its just a random thing. It has no overheating issues or anything, just a missfire when it happens....I can actually tell when it has happened now. I was going to order the new S.S. JE ProSeal Headgasket but they dont make one for an h series yet. Any positive info would be appreciated. Thanks in advance.

 

I could be wrong but with that much pressure you may need to Oring the head? or block.

 

Yeh, by not running a .5mm over bored headgasket lol all aftermarket head gaskets (besides custom bore gaskets) are designed to allow for .020(.5mm) over bores.

Use one of the following...

FEL-PRO Part # 26411PT
VICTOR REINZ Part # 54241

 

That would depend entirely on the amount of horsepower he is making.

 

I was wondering if that .5mm over cut gasket would help tuck away the edge of the gasket and give it like a "buffer" area?

 

Its close to 550-600hp

 

Most of the problems with overbored gaskets occur with how much material there is in-between the cylinders. It's the same concept when you over bore the block itself, you take away from the material on the joint between the cylinder walls, making it more likely to fail at the thinnest point. Do you know where exactly your gasket is failing?

 

Realistically you should be looking at o-ring's, IMO.

 

Ive been using the stock Honda headgasket. And it seems that its right on the edge. It always as a small burnt area on the edge every time

 

Damn... I kinda figured that. I guess I might have been in denial. lol

But ive seen several setup pull about that much on a stock gasket. Idk really. I guess its right on that edge of needing to do something different

 

There is no need to o-ring for your application.

Are you sure nothing is wrong with your heads studs? As in, they are bad or the holes are bad. Also, is the head and block in spec?

Stick with what works, OEM gasket/Golden Eagle.


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What does your head gasket surface look like? (head and block side)

Can you feel any grit with your fingernail?

 

You don't need o-rings for that power. Start looking elsewhere.

Bent block or head or even a sunken sleeve(which can be minimal).

 

check flatness. copper spray new gasket. go at it again lol.

 

I'm not a fan of copper spray. In terms of using a sealant on the headgasket, less is always more. Just use a very light amount of RTV sealant or Hondabond on the key areas outline in the Helms manual.

Also, no sealant is going to prevent a head gasket from blowing, this OP has a larger issue at hand.

 

you should never need to put anything on a MLS head gasket, and ill stand by that for as long as i continue to build engines. There is a specific reason they are coated in viton and you shouldn't try to interfere with that, this isnt the 1960's.

 

This block is an FRM closed deck so I dont have sleeves to sink, and the last time I had the head off I straight edged it with feeler gauges and it is still flat from the last resurface. I was reading that the head and block surface need to have a certain RA (Roughness Area), and not a real slick/smooth surface. A place for the hg to grab I guess. Kind of like sanding/priming is to car paint. So I will look at that too.

 

Are you sure the head isn't lifting? High HP/boost level sohc's love to lift heads

 

im curious what cures this set up myself