Head Gasket thickness selection

Grandavi

Active Member
Authorized Seller
Joined
Sep 25, 2008
Messages
2,657
Likes
0
Location
Calgary, Alberta, Canada
I wouldn't worry about it, unless it happens. Easy enough to monitor. You may be lucky and not have any issues at all.
However, if you get bit by the power bug (which usually happens) and want to up your boots to 14-16 psi, Im not sure the stock headgasket would hold. but for 10 psi from everything I read (meaning.. I'm not a mechanic) I think it will be fine. The internals will hold that easily enough if they are in good shape. I wouldn't worry about the BOV too much unless your going to be doing an intercooler upgrade.

My car with a similar setup to what you just listed was a really big surprise when I got it on the road. Amazing feel. I, however, rebuilt everything and have a 2.0 Cometic metal head gasket and forged pistons. Figured I would overbuild rather than just go with OEM.
After doing everything though, I would have stayed with OEM pistons if I knew what I know now. The forged are better if your going to track the vehicle.. for street and under 500 at the wheels, the OEM are actually better suited imo.

Anyway... if you don't have to, just leave the head alone (after you check the compression and do a leakdown test to make sure everything is actually tight.

And again.. I am a Supra enthusiast/owner.. not a mechanic.
 
Last edited:

Tysan

New Member
Authorized Seller
Joined
May 5, 2013
Messages
44
Likes
0
Location
Lexington, NC
I thinking about putting a JDM 7mgte in my 89 mkiii shell. From what the ppl at the dealership says it has less then 65k on the motor. I don't know how hard its been driven so I just have to take my chances. Do you think I should replace the HG even if its good or get some ARP studs and retorque it. If I do replace it even if the HG is still good would I still have to resurface the head and block? Im new to the scene so please go easy on me.
 

TheMechanic253

New Member
Authorized Seller
Joined
Aug 11, 2014
Messages
35
Likes
0
Location
Puyallup
My machinist told me to install the piston and rod and torque it to the crank journal. Then set the piston at TDC and put a flat edge over it since it sits above deck. then use feeler gauges between the straight edge and the deck of the block. You take that number and at +.035" and that's the minimum head gasket thickness you want to run. This is closest safe distance to maintain quench. I believe that it will change your compression ratio from stock, this is the tolerance that the engine should be able to handle with a tune of course.