So wich head gasket

[cruzinbill]

There are so many damn metal head gaskets what do you guys think would be the best?

 

[NDBoost]

i personally went with a 1.2 MHG from HKS

 

[cruzinbill]

how much are you boosting and how long have you had it

 

[NDBoost]

12lbs ive had it for a month or so, i torqued to 95 ft lbs. I only machined/cleaned the head, i cleaned the block up real good and used copper spray.

 

[shaeff]

Cometic MHG. most forgiving in terms of RA. i've got over 1k miles on my build, pushing 15psi on a stock CT, and i have a lead foot. no problems.

HKS, TITAN, and GREDDY metal headgaskets all require an RA of 10 or less, whereas the Cometic requires an RA of less than 50. much more forgiving than the others.

i'm torqued to 90ft lbs with ARP studs, using the moly lube. when i did my HG, i cleaned the block super well, until it was shiny, coated my Cometic MHG with permatex brake quiet, put it on, then torqued it in sequence. works like a charm.

-shaeff

 

[cruzinbill]

ok RA? having a dumb moment what is it and this is always the part i suck at choosing the right gasket.
I want to go with the Cometic but wich size.
Do I have to wait till after my head is decked to find out wich to go with.

 

[mkIIIman089]

Roughness Average, I don't know the exact definition or measurement, but the lower the number the harder it is for most machine shops to get to.

Correct, you need to find out how much was taken off, then add that to 1.2mm (stock thickness) and buy the closest size available to that total.

 

[shaeff]

^ correct. RA is the roughness average, basically, a high RA wont be as smooth as a low RA. the lower the RA, the closer to a MIRROR finish you get.

also correct on the HG size.

-shaeff

 

[Supra5MGTE]

do you need to spray the metal head gasket with copper spray? what's that do exactly?

 

[shaeff]

do you need to spray the metal head gasket with copper spray? what's that do exactly?

no, you're not supposed to have to spray a MHG with ANYTHING. i prefer permatex brake quiet, as it wont melt and get into the water passages. all the coatings do is help the MHG to seal better.

-shaeff

 

[cruzinbill]

ok this is still kicking my ass and i dont know why lol. so the head was strait ass hell so im going with a stock thickness HG. So what HG should I go with there are so many types. like bead stopper. and is our stock bore 83 or 84. Id like to go with the Toyota Supra 86-92 Bead (1.2mm thick, 86mm bore), 4715. But would it work since it says 86mm bore