That-Guy

iTrader: (1)

hey guys, i'm getting conflicting info all across this board and other boards, so i want to clarify.

What is the thickness of the STOCK TT (2jzgte) headgasket?

Thanks guys.

Gunnar

I've always read 1.3, what else have you seen on it?

That-Guy

iTrader: (1)

well that confuses me even more. I always thought it was 1.0 mm for some reason, can't remember where i read that, but that was the impression i had, then i heard that the stock tt headgasket would bring the cr of a ge engine down to 9.0-1 and that conflicted with the theory that the cometic 1.3 mm (1.3 being thicker than 1.0) brought the cr down to 9.2 or 9.3 to 1. So i did some more research and found a few places or boards saying that the stock tt was 1.6mm which made more sense with the cr everyone was saying for both the tt and the cometic 1.3. So i thought i'd figured it out with this new 1.6 info so i called my lexus guru/ mechanic to confirm and he said he thought the stock tt was actaully 0.7mm. So now i'm totally lost. Is there any definate source on the web for this info?

lexforlife

iTrader: (7)

tt hg is in fact 1.6mm but when trq down to 86ft lbs on the headbolts it compresses to about 1.3mm so on a ge block with na pistons effective compression would be 9:2:1 which is nice imo only f you have standalone if running more then 15lbs of boost for controlling timing and precise fuel delivery is criticial to ward off detonation..


my plans when i build a fresh block is to effectively run a even 9:0:1 compression with cp custom forged pistons .. because of using a aem my tuner recc this for off boost driving will be peppy as hell , it will spool turbo quicker and provide for better power band

Gunnar

The higher the compression the better gas mileage you get out of boost, also. Good info on the beginning thickness v. compressed thickness, didn't know that.

That-Guy

iTrader: (1)

called cometic today, asked about the stock thickness of the 2jzge hg, but i think they thought i was talking about the tt, they said the compressed thickeness of the stock was 1.3 which matches what lexforlife was saying. Hoever i also picked up some very unsettling news. Cometic said their headgaskets are coated with a sealant material that requires the head and the block to be machine milled to an extreme "glass" smooth, far smoother than stock, for the gasket to seal idealy, There is no way i am going to pull the block and go get the head machined. I don't know if this is for 200k plus mile longevity purposes or if this is normal and that people who do their hgs do this?

I can't remember hearing anyone talk about this before,, any info???

5sp_jzz30

iTrader: (2)

if you are going to do a metal head gasket then decking the head and block to make ideally smooth is a must. stock head gasket can be used without the need to machine the block and head. just make sure it is extremely clean and bare.

aftermarket HG are stiffer then stock and wont seal well on a rough surface.

doesnt seem like you have done any research at all since there is a thread about 10 threads down from yours that just discussed some issues with the HG. reading it would answer at least half your questions.

in all honesty, not to be a d1ck, but i dont think you should be doing this on your own if you can even do all the research. doing a HG is not hard at all but it is very easy to screw it up. i do all my stuff myself and i love DIY people but if you cant find all the info and cant do it right then maybe you shouldnt be doing it. the info is out there. sometimes google, and not here, is your best friend....aka search more...

btw, i think you will probably ask this, and if you dont then you definitely shouldnt do your own work, but the stock head bolts should not be reused and ARP would be a preferred fastener.

That-Guy

iTrader: (1)

all the info is out there and so is a lot more incorect info, i specifically said i was getting conflicting stories which is why i posted this thread for clarification and confirmation, not because i hadn't read all the other threads 5-6 times over. Thank you for you're input, this info is what i was looking for because truly i am not up to the task of pulling the engine and doing all that work myself. This is why i ask for clarification on whether or not this needs to be done.

SC300_704

iTrader: (5)

i always thought it was 1.3mm

5sp_jzz30

iTrader: (2)

^^^head gasket advertised thickness is always its compressed thickness. it really doesnt matter how thick it is out of the box. as long as it compresses to whatever the specification is then youre fine. multi layer metal head gaskets will be "fluffier" when out of the box but compress nicely. its usually not as simple as taking a digital caliper and measuring the thickness. it can work as a guide but its not accurate.