so i got back my head from the machine shop and they said they took off 4 thousandths of an inch which i realize is very little. what size heasgasket should i get and what type (felpro or cometic) i e apr studs. i plan on running 550s, afm .57 ct26. i noticed cometic had one thats 5 thousandths of an inch thick would this be fine ?
which headgasket
- Thread starter RiyadYar
- Start date
It would be best to go with a metal head gasket like HKS. So you dont have any chance of blowing a head gasket.
i took only the head out the motor and the block was still in place so thats why i decided not to go metal because only the head was machined. the block it still pretty smooth but i would never put a mhg unless i had the block and head done.
^^^ You've been reading 
I prefer the Toyota OEM HG, but a lot of guys are using the Felpro with success. I'm sure a Cometic composite HG would also be a quality gasket. Both Toyota and Felpro have head kits that include all the gaskets/seals you will need to replace. Don't use the Felpro EGR cooler gasket...it's crap. If you did not have a valve job done (that would be a good idea), you will need cam seals, intake/exhaust gaskets, and valve cover gaskets at minimum.
Since your machinist took off such a small amount, a stock thickness HG would work well. I would use copper spray on an OEM type HG...a couple coats, then carefully lay it down on the block using the index pins for alignment. Be careful, you get one chance
Don't forget to put RTV on the top of the rear timing plate where the TSRM shows. Otherwise you will have an oil leak.
I prefer the Toyota OEM HG, but a lot of guys are using the Felpro with success. I'm sure a Cometic composite HG would also be a quality gasket. Both Toyota and Felpro have head kits that include all the gaskets/seals you will need to replace. Don't use the Felpro EGR cooler gasket...it's crap. If you did not have a valve job done (that would be a good idea), you will need cam seals, intake/exhaust gaskets, and valve cover gaskets at minimum.
Since your machinist took off such a small amount, a stock thickness HG would work well. I would use copper spray on an OEM type HG...a couple coats, then carefully lay it down on the block using the index pins for alignment. Be careful, you get one chance
Don't forget to put RTV on the top of the rear timing plate where the TSRM shows. Otherwise you will have an oil leak.
jdub;1307165 said:^^^ You've been reading
I prefer the Toyota OEM HG, but a lot of guys are using the Felpro with success. I'm sure a Cometic composite HG would also be a quality gasket. Both Toyota and Felpro have head kits that include all the gaskets/seals you will need to replace. Don't use the Felpro EGR cooler gasket...it's crap. If you did not have a valve job done (that would be a good idea), you will need cam seals, intake/exhaust gaskets, and valve cover gaskets at minimum.
Since your machinist took off such a small amount, a stock thickness HG would work well. I would use copper spray on an OEM type HG...a couple coats, then carefully lay it down on the block using the index pins for alignment. Be careful, you get one chance
Don't forget to put RTV on the top of the rear timing plate where the TSRM shows. Otherwise you will have an oil leak.
When I got my engine done my head and block were milled to a combined .5mm. My cylinders were also bored .5mm oversize too. I put on a hks 2.0mm mhg because that's all I had. Is the compression ratio significantly lower now? I feel like there is less low end power than before when I had a 1.2mm mhg on there with the block and head not milled. Thanks
yz-125;1307225 said:
No...the stock HG is 1.37mm compressed. You took off 0.5mm, requiring a HG 1.87mm thick...2.0mm will reduce compression slightly, but will also allow a higher boost level (with a proper tune).
The 1.2mm HG actually raised compression...what you perceive for low end now is probably correct. The lower compression from the 2.0mm HG will have an impact on low end power (off or at beginning of boost). Compared to the 1.2mm HG, it would be a noticeable difference.
jdub;1307262 said:
Jdub, what would be the most a machine shop can take off and still use a stock HG. If more was taken off you'd need to get a different head gasket to make up the difference, I was just curious.
jdub;1307262 said:
oh, I thought the mhg has a bigger bore so they made it thinner to keep stock compression. Is there a 1.7mm mhg out there?
Teal - The TSRM max allowed warpage is:
Head - 0.0039"
Block - 0.0020"
Implying both can be machined out to produce a flat surface, otherwise it says to replace the head/block. That would be the most I would remove, but would still try to get it back as close as possible to the stock height with a thicker MHG. Playing with compression using HG thickness is fine if it is relatively close. Otherwise, you will start having issues with the timing...i.e. the cam gears and crank indexes will not line up correctly.
yz - Cometic can make a MHK at any custom thickness. Like I said, the 2.0mm you have on there now is close enough.
Head - 0.0039"
Block - 0.0020"
Implying both can be machined out to produce a flat surface, otherwise it says to replace the head/block. That would be the most I would remove, but would still try to get it back as close as possible to the stock height with a thicker MHG. Playing with compression using HG thickness is fine if it is relatively close. Otherwise, you will start having issues with the timing...i.e. the cam gears and crank indexes will not line up correctly.
yz - Cometic can make a MHK at any custom thickness. Like I said, the 2.0mm you have on there now is close enough.
Running an upgraded CT26, you'll be fine...the best useful boost you'll get out of that is 14-16 psi.
Keep in mind, you'll need a Lex AFM or some sort of fuel control (or both) to run those 550's...it all depends on how you tune as to how long a OEM HG will last.
Keep in mind, you'll need a Lex AFM or some sort of fuel control (or both) to run those 550's...it all depends on how you tune as to how long a OEM HG will last.