New M20 Head Gasket Option

[TobyB]

Corteco head gaskets are quite good, generally speaking.

t

[digger]

Thanks AWDBOB,

Part of me thinks, "might as well go bigger if I need to buy new pistons

with a turbo engine this makes sense as off boost it will be better and the turbo efficiency when chosen can help the top.

If NA you would not want the biggest cubes of trying to make power as unless you improve the breathing correspondingly as you just you end up with a mismatch in parts that dont work together that is why 3 to 3.1L doesn't make any more power than 2.8/2.9 and sometimes makes less when used with a stock head and intake with a very mild cam and it just makes more torque

[kyleconstantine]

Last may when I got my 2.9 stroker going I had lots of problems with my hg leaking. I pulled the head 5 total times and tried every brand. It turned out that I just needed to keep heat cycling and retorquing the arp studs. It probably took about 15 times and I also used the anerobic sealer in a couple spots. I think any of the gaskets would have worked if I stuk with it. So just don't give up on the new hg so easy.

McGyver I have a torque plate for the m20 if your machine shop hasn't got that far yet. What shop are you using for the work?

[McGyver]

digger , It makes sense that that an NA engine struggles to flow with 20% more volume. I'm definitely going to stick with the 2.7i approach.

Last may when I got my 2.9 stroker going I had lots of problems with my hg leaking. I pulled the head 5 total times and tried every brand. It turned out that I just needed to keep heat cycling and retorquing the arp studs. It probably took about 15 times and I also used the anerobic sealer in a couple spots. I think any of the gaskets would have worked if I stuk with it. So just don't give up on the new hg so easy.

McGyver I have a torque plate for the m20 if your machine shop hasn't got that far yet. What shop are you using for the work?

Oh yeah, I forgot you had that! They already align honed the main bearings. Is a torque plate needed for that step? The block is currently getting magnafluxed. I'll text you about that torque plate!

I went with BMS (Budz Motor Sport) in Plymouth Meeting. They were suggested by several independent sources and seemed knowledgeable. Definitely going to be slow and pricing is somewhat of a mystery, but I'm hoping it all works out fine.

[kyleconstantine]

Always curious about the machine shops around here. I went to bison motorworks on someone's suggestion and they did good as far as I can tell. Yeah let me know if you need it I'm happy to lend it out locally. I wasn't cheap and it will be years before I need it again.

[digger]

Last may when I got my 2.9 stroker going I had lots of problems with my hg leaking. I pulled the head 5 total times and tried every brand. It turned out that I just needed to keep heat cycling and retorquing the arp studs. It probably took about 15 times and I also used the anerobic sealer in a couple spots. I think any of the gaskets would have worked if I stuk with it. So just don't give up on the new hg so easy.

McGyver I have a torque plate for the m20 if your machine shop hasn't got that far yet. What shop are you using for the work?

IMO its the same issue with VC gaskets, periodically retorque until they nolonger "budge" and the leaks will stop.

From a HG perspective this is one advantage to the ARPs as you can keep retorquing, you could argue that the TTY factory style bolts arent as sensitive but anecdotally the same issue with leaky oil return occurs on factory bolts and ARPs from what it seems

[TobyB]

...but M20 head bolts aren't tty... ?

t
just the rods, ma'am, just the rods.

[digger]

...but M20 head bolts aren't tty... ?

t
just the rods, ma'am, just the rods.

idk for sure, but if you are doing a "snug tight" and then angle tighten with a bolt that is waisted in the middle and a one time use thats normally TTY

[TobyB]

Aha- it's a 'crush to spec' head gasket!

So doing lots of M54s with tty bolts, they get 3/4 a mm or so of stretch. 180 degrees in 2 90's.
VW gets 1.5- 2, and it makes me want to throw up, that 'soft' feeling.
You know what I mean, that 'it's gone soft, now I've stripped it' feeling.

But what's happening with M10 and M20 head bolts and gaskets is that the BOLT isn't
tty (it's way too big) but the head gasket CRUSH is what they're adjusting with the '25 degrees and another 25 degrees'
thing.
If you go too far, you can feel the resistance (which has been pretty constant for the 25 degrees) spike as the head bottoms.
I tend to think of it like the crush washers on spark plugs- you can feel it touch, then crush at a constant pressure, then when
you've re- used them too many times, they bottom and now feel like a Ferd.

'Course, if people are now using M54 stretch bolts (or similar) on E30's, ignore me.
But last I did it, the bolts weren't tty. And yes, it's been 15 years or so, maybe there ARE tty's for the M20?
They weren't when they were new.

t

[82eye]

Aha- it's a 'crush to spec' head gasket!


But what's happening with M10 and M20 head bolts and gaskets is that the BOLT isn't
tty (it's way too big) but the head gasket CRUSH is what they're adjusting with the '25 degrees and another 25 degrees'
thing.

i've never seen a head work or gasket diy that didn't include new head bolts. i've done them on both m10's and m20's. can you show me one where it says it's ok to reuse the head bolts ?