What will a stock head gasket hold with 12mm studs? How long will a o-ring head gasket last and what pressures will it hold? Same with fire ring how long and how much pressure? My head is ok except for a couple of valves and seats but has to go to the machine shop do i do o-rings or leave it stock with studs? Thanks guys!!

 

depends on what you do if I recall i think a stock gasket hold about 50psi with studs

 

There's guys running alot of power with stock gasket and studs only. I was told a few times that 800rwhp and the stock gasket and studs are about as far as you should go.
If you already removed the head and are having work done, I'd talk to some builders about what they recommend. Now's the time to do it...

 

I ran 90psi and only blew the HG barely because I was running water/meth and 30 degrees of timing advance....and even then it took quite alot of hard runs. With studs properly installed it should hold 70psi. Once you go to O-rings you are down to a 2nd gen gasket and with fire-rings ....same thing. IF you were tapping the block for 14mm studs I'd get a set of fire-rings...IF you were planning on big twins someday. O-rings are more a 2nd gen thing where they didn't have a MLS gasket. ks

 

yeah i wih they would come out with a MLS gasket for us 2nd geners

 

In a conversation with Greg Hogue who was the former driver of the world's fastest diesel pickup,... he told me he doesn't recommend "o"ringing or fireringing and that the Dr. P truck runs the stock headgasket. I think that means it's good enough for most of us.

 

I regularly see 50-60 plus psi on a stock HG with no studs...they have been on my bench for 2 months already. I run a Silver bullet on my truck w only the smarty doing timing. It has held up very well and quite a few other trucks too. The 12v and the 24v isb have more to address as far as the head is concerned bc there is no current MLS HG. The stock 3rd gen peice is quiet capable...just watch your timing!

With studs (12mm) and a FLAT machined head surface, 70 plus is not a problem.

Richard

 

Thanks a lot guys sounds like stock head gasket will work better and cheaper!!

 

What do you mean by mls?

 

multi-layed steel, MLS

 

I agree I think the main step most miss is having the head decked at a machine shop. I had some valve seat issues so while it was off I had it machined flat. Its kind of a pain but with a flat head good gasket and studs I would say 70psi isnt a problem.

 

The Key is a flat head to block deck surface...Mine had a low spot between 5 and 6 cylinder on the deck and the head was within spec but you add the two tolerances at their worst up and you have a loose head. I sanded my block deck and was able to get it within 1 thou over a 2 foot straight edge accurate to 1 thou....starting off it was +-5 thou and one low spot of 8thou. When I ended I had the low spot within 2 thou of the surrounding foot and 1 thou within the stud spacing. The head was machined to 1 thou and it was out at the limit of spec but still within spec. For me it was just a matter of time until it blew. If you are lucky and your interface is nice and flat ... or the low spots on the deck match the high spots on the head...the mls will easily hold 70psi with studs and 50psi with stock...Not all of us are lucky enough to have a perfectly flat interface. With stock pressure....the MLS head gasket has a good margin of safety. Greg Hogue only ran 60psi on his external wastegate....with a ton of nitrous keeping the temps cool. The MLS would last forever at this as drive pressure is limited to what the external wastegate is set for. Put on a set of twins that only wastegate to the big turbo and drive pressure can spike. ks