Headgasket Boresize

[siccdragon]

I've done some searching and i just wanna verify what I've read. First of all I just had my entire engine rebuilt, bearings, decked and milled, everything. But I didnt have to bore it at all and stayed with stock pistons that are ~83m but i was wanting to put an HKS bead gasket on but the only bore size i can find is 86mm, in other posts they said some ppl just run them with the larger sized HG. Is there a MHG that is stock bore size or should i use the 86mm one?
Thanks

 

[hvyman]

86 is fine.

 

[siccdragon]

Alrighty, thanks!
Another real quick question, when the MLS says 1.4 thick is that compressed or uncompressed? Cause the machine shop said it was minimal that they milled off (gonna call for exact) but should a 1.4 be fine or am i gonna have to get a 2mm. Cause when I asked them the size i should get they shrugged and said 1mm which is think is real skinny.

 

[gaboonviper85]

Take the head back to them and demand they measure from the deck too the valvecover gasket surface....stock legth is 116mm...my head that was just rebuilt measures 115.95mm so I'm safe too use a factory thickness hg...

Toyota doesn't list it's tolerance from the factory for this...my machinist swears he took off ruffly .008" but my measurements say I'm only .001" shorter....you may be fine....If you have access too a vernier caliper you can measure it yourself.

 

[jdub]

The stock HG is 1.37mm compressed. A MHG does not compress

 

[siccdragon]

The stock HG is 1.37mm compressed. A MHG does not compress

Silly me for some reason I was thinking there would be a crap ton of viton adding to the thickness

 

[radiod]

Silly me for some reason I was thinking there would be a crap ton of viton adding to the thickness

Negative, the thickness on the metal HG is what you get

 

[siccdragon]

One last question... were they supposed to machine the top of the rear timing cover cause it looks like it sits 1-2 mm higher than the block...

 

[jdub]

Yes. If it is not level with the block deck (or slightly less), the HG will not seal. Also, 1-2mm difference is an awful lot....how much did they take off the block deck?

It's a good thing you noticed it now

 

[siccdragon]

They were vague... said enough to make it level... I'm gonna see if maybe when I bolted it to the block like that tomorrow morning. I know they are reliable cause they build race engines for chevy's and stuff but seems like the 7m may have been a whole nother world to them. I think im gonna call them tomorrow :icon_evil

 

[jdub]

If you can feel any "lip" between the block deck ant the timing cover, it's too high and will not seal. I am 100% sure on this one.

You want to lay the MHG on the block deck a look at the rivets holding the MHG together. If an rivet touches the deck, remove it or the same thing will happen.