milling my 95 gst head

[bstaley]

Hey guys new to dsm forums, first post. Anyways, I have recently purchased a 95 gst with a blown head gasket. So I sent it to a local machine shop to check the integrity, if its was wrapped ect. Turns out it was 1/3000ths wrapped. also since it had a blown head gasket it needed to be milled. The machine shop is wait for my ok to mill it because the machinist didn't know if I could get a shim. Turns out I can't... so my question is should I have it milled and get a thicker gasket like a cometic and arps or just get a new head? Sounds extreme to get a new head but I have my eye on a jdm for around 350 shipped... also if its being milled 1/5000th would a 1.6mm thickness be fine?

 

[fourgsixthree33]

How much are you paying to get the head milled?

 

[bstaley]

Havn't heard for my machinist yet but I'm guessing around 70-80

 

[insanebum]

At the shop that i work at we send out heads all the time for straightening. i dont know exactly how the do it, but when they come back they are straight without needing a mill. might be a possibility for you.

 

[307dsm]

-U don't need a new head if it looks like this...

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-U see the circles that i circled... that is the limit that u can cut your head.
-So if that whole circle looks completely flat with the inner circle then u may need
a new one.

-I don't think u need to use 1.6 thickness gasket, unless u are super cutting your head and your block.
which by the way check your block deck to be in spec because if u just cut the head and install a cometic gasket there is a chance for your engine to leak oil...

-Since u are wanting to use cometic gasket its
better if u mill cut the head and block
you will get a nice mirror finish like my second pic..
and a good sealed engine....

 

[bstaley]

At the shop that i work at we send out heads all the time for straightening. i dont know exactly how the do it, but when they come back they are straight without needing a mill. might be a possibility for you.

At beginning of this process I talked to him, just to find out some more info he actually said that if it was wrapped bad enough they bolt it down to this plate and stick it in an oven to staighten it. But I thin he mainly needs to mill it because of thed blown head gasket, though I'm not sure. Thanks for the reply.

-I don't think u need to use 1.6 thickness gasket, unless u are super cutting your head and your block.
which by the way check your block deck to be in spec because if u just cut the head and install a cometic gasket there is a chance for your engine to leak oil...

-Since u are wanting to use cometic gasket its
better if u mill cut the head and block
you will get a nice mirror finish like my second pic..
and a good sealed engine....

Honestly, I have no brand favorite.. but cometic was the only reasonably priced thicker gasket. I believe that the stock thickness of a hg is 1.5mm or .51"(please correct me if I'm wrong) so the next step up is 1.6mm or .66".

I was told for the block to just clean it up with a wire wheel? Any thoughts?

 

[Arthris]

I would use a buffer wheel for removing gaskets. They work very well. I would take a straight edge to the block first and see if it is warped at all. You can find the specs in the Manuel. I would also check the cylinders for out of round. check the Manuel on that also. If the out of round is good at least have the shop hone the cylinders.

 

[bstaley]

I would use a buffer wheel for removing gaskets. They work very well. I would take a straight edge to the block first and see if it is warped at all. You can find the specs in the Manuel. I would also check the cylinders for out of round. check the Manuel on that also. If the out of round is good at least have the shop hone the cylinders.

Thanks for the advice.. I definitly need to check the block for staightness still, but as far a the cylinder walls I can stll se from before where the last owner had it honed

 

[Palmetto_TSi]

use a wire wheel that attaches to your battery drill. Battery drills don't spin fast enough to allow the steel wires to gouge into the aluminum head. Use light pressure and some light oil... Air tool oil works great. It helps loosen the gasket material and also helps keep the steel wires from gouging the head. Once you are done you can buff it, but the truth is the little brush marks on your head will actually help it seal by cutting into the gasket.

now, did the machinist say it was off 1/3000" or 3/1000"? I'm betting the second one, because 1/3000 is well within spec.

 

[bstaley]

now, did the machinist say it was off 1/3000" or 3/1000"? I'm betting the second one, because 1/3000 is well within spec.

He said it was a 3000th off and he was gonna mill it a 5000th

 

[Palmetto_TSi]

ok, that's what I thought. .005" = 0.127mm and unless you are really building an all out race engine, a stock thickness gasket will work fine.

 

[bstaley]

I'm assuming that milling it a 5000th is to take care of where it had slight imperfections from where the hg was blown. Because when I recently talked to him he seemed to shurg the 3000th off as it were no big deal. Ill get ahold of him in a little bit and post exactly what he said

 

[Palmetto_TSi]

3 thousandths isn't much at all, but it is just barely out of the flatness call out of 2 thousandths. Another thing that you have to take into account is if this head has been milled before, and if the block deck has been milled before.

here is a link: Mitsubishi 4G63 & 4G64 Engine

pages 11F14-11F15 have the flatness call out. If the deck and or head have been milled before, you may need the thicker gasket. Even then, I doubt it will hold a lot of boost.

 

[bstaley]

Even then, I doubt it will hold a lot of boost.

I'm hoping with the cometic and some arps at least 15-20

 

[Palmetto_TSi]

yeah you should be fine.

 

[bstaley]

Well after searching for hours online I think I finally found out that the stock gasket size is around .051 inches. Which would make the stock in mm's around 1.3. So I def should be fine with cometics stock thickness of 1.5 matter of fact that may be a little too much but o well little less compression will save me in the long run. If anyone can prove me wrong please do!!