MHG cometic

PynkEye

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Mar 30, 2005
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hi, since im not resurfacing the head or block, im going with the cometic
or something, was just wondering in the 3 they have, wich one do I choose....bore size and thickenss ??? i dont really understand, i would want 1.2mm but they hav eother numbers.
If you could point out the code and price of the one I need, id appreciate, dont wanna make a mistake.

Thanks guys

http://www.horsepowerfreaks.com/viewproduct~Toyota~Supra_86-92~~Engine~Head_Gaskets~.html
 

souprat

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Mar 30, 2005
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just get whatever closest is what everyone says. but i would urge you to resurface the head at least, your really supposed to resurface both. i managed to get away with only surfacing the head, hasnt blown yet. but aluminum heads warp so easaly thats its kinda a must as far as i know. btw, i'm running a 1.2mm,86mm bore ater taking .007" off the head.
 

TONY!

Habitual Supra Killer
Mar 30, 2005
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PynkEye said:
hi, since im not resurfacing the head or block, im going with the cometic...
A Cometic is a metal gasket. You still need to have the surfaces smooth. Less than a RA (roughness average) of 50. See pic below.

PynkEye said:
....bore size and thickenss ??? i dont really understand, i would want 1.2mm but they hav eother numbers.
If you increase your bore (have it bored out) you get the bigger one in that sense.
IIRC, OEM HG thickness is .056" or .054" The more you have milled off of the head & block combined, the more you will need a thicker gasket.

The following is what Cometic recommends in terms of smoothness.
p16602_1.jpg
 

PynkEye

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Mar 30, 2005
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damn so im doomed, this car is the only car i have, and I cant take it appart and let it stand for a week to get thte head resurfaced and shit.

whats my alternative ??? OEM gasket ??? from Toyota ? will I be able to run 350hp on those torqued 72lbs
 

empera

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listen man, if u have taken off the head, check the block, make sure theres no warpage or pitting. Clean the mofo with gasket remover and a gasket scrapper, which can all be found at autozone, the both work wonders...
Send the head out to get machined, it wont be much!! ...then get the 84mm 1.31 (i believe) Cometic HG, ARP Studs, torque it at 80-95lbs, and ur pretty much set...i would include more details but i dun think ur that dumb to miss small details.
 

souprat

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PynkEye said:
damn so im doomed, this car is the only car i have, and I cant take it appart and let it stand for a week to get thte head resurfaced and shit.

whats my alternative ??? OEM gasket ??? from Toyota ? will I be able to run 350hp on those torqued 72lbs


the machine shop that i took my heads to only took a couple of days to mill the heads. and a few days added ontop of a two month long job(2 month for me anyway) is not alot. and yeah i agree with empera, clean that block real good. maybe hit it with some 1000 grit sandpaper to polish it up real nice. it will be worth it.
 

PynkEye

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empera said:
listen man, if u have taken off the head, check the block, make sure theres no warpage or pitting. Clean the mofo with gasket remover and a gasket scrapper, which can all be found at autozone, the both work wonders...
Send the head out to get machined, it wont be much!! ...then get the 84mm 1.31 (i believe) Cometic HG, ARP Studs, torque it at 80-95lbs, and ur pretty much set...i would include more details but i dun think ur that dumb to miss small details.

Do I have to take out the SparkPlugs ???

K, ill check out the shops around here that are ''competant'' and maybe arrange to have my moms car for a week :kloguck: , whats the max they should take off ?? if they ask.

And just for personnal info, how much hp can a OEM gasket take ? hp
 

empera

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im sure the oem gasket can take a good amount, not too sure wats max...but 1. i wouldnt risk it and 2. why not get it done the right way while ur in there...

you need to take everything off the head to get it machined...but dont hafta take everything off to take out the head from car. to make things easier remove the hood.

hopefully u have a garage and good amount of resources (tools and such).
Let us know, how everything goes.
Also, where are u located?
 
M

MisterTurbineTwister

Guest
spark plugs should be the least of your concerns for component removal.

Once you have taken the head off of the car and have disconnected everything else, removing something like spark plugs should be a walk in the park.

The stock head gasket, with new bolts can withstand about 9 PSI of boost torqued at 70ft lbs. Any higher and you're asking for trouble.

I would say no more than 300hp on a new stock replacement gasket MAX. I wouldn't trust anything above 280-300.

The best thing you can do is drive something else while you do the job and DON'T rush it. If you do, you will forget something as simple as cam position sensor placement or connecting a simple hose and the car will hate you for it.

Tell the machine shop to take as little off of the head as they need to in order to acheve the finish for a MHG. The idea of a thick metal head gasket is that it is stronger and it lowers your initial compression ratio for accepting higher boost levels.

I would go with a 2.0mm if you can afford it. It adds a little streingth and lowers the compresion a little more for more boost.

http://www.andysautosport.com has an HKS 2.0mm gasket for $256.50 as well as other sizes/ thicknesses from HKS and GReddy.

The direct link to the head gasket is:

http://www.andysautosport.com/products.php?id=To86Supra&make=Toyota&mcat=Engine&scat=Head Gaskets

Good luck with your ride! Just double check everything before you move on to something else.
 

Idealsupra

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Mar 31, 2005
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www.tampabaysupras.com
empera said:
listen man, if u have taken off the head, check the block, make sure theres no warpage or pitting. Clean the mofo with gasket remover and a gasket scrapper, which can all be found at autozone, the both work wonders...
Send the head out to get machined, it wont be much!! ...then get the 84mm 1.31 (i believe) Cometic HG, ARP Studs, torque it at 80-95lbs, and ur pretty much set...i would include more details but i dun think ur that dumb to miss small details.

wow this sounds VERY familiar :bigthumb:

why do people INSIST on cutting corners? god damn...dont resurface shit and youll be back here btichign about another bhg for sure.... i just dont get it... :icon_roll
 

souprat

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Dont worrey about it. doing the hg for the first time seems like a reallly big deal but when you get it over you realize that it wasnt that hard. like everyone said, take you time, do it right. and yeah, after you wrestle with the turbo, or finding all those bolts one the bottome part of the intake manifold, the you wont even think of the sparkplugs.
 

souprat

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and one more thing, the machine shop will not ask how much they should take off, they dont know. they shave off metal untill it is flat and no more. be shure you ask how much they took off, you need to know this when you order your hg so you know what size to get.
 

PynkEye

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Mar 30, 2005
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lol guys, the spark plus was a job :p lol

I dont wanna cut corners, im just trying to learn stuff, like how much oem gasket can take, and if i needed to resurface absolutely etc....

Ill probably get a car for 1 week, so hopefully the machine shop can do It then.

How do I sand down the Block, what grades ??? finished with 2000 ok...but do I start out with 500 or something ??? and a big sanding board ??
 

kamil

87T Targa
Apr 4, 2005
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I personally wouldn't sand the block, theres no way you're going to take identical amounts off every part that you sand... The OEM gasket has been known to handle 350rwhp just fine when torqued to 72-75ft/lbs on a head/deck that are not warped and are properly cleaned & prepped. Now, your mileage may very well vary if you do not check for warpage, don't prep well enough, don't torque in the proper order, etc. ARP hardware is highly recommended since our bolts have had 15+ years of extreme temperature changes on a daily basis.

Like everyone has said -- your best bet is to send the head off to get milled until it is flat (machine shop will know). Have them tell you what they took off, order your gasket accordingly to compensate for the material removed from the head. Prep the block deck with some really good solvent and fine steel wool, check for warpage (autozone tool)... Keep your cylinder walls oiled so they don't rust. When everything is back, use either ARP head studs or bolts (studs are preferred). Torque to 85ft/lbs using the procedure in the Supra tsrm (www.supratsrm.com). Don't use any kind of gasket spray. Never worry about bhg again.
 

lagged

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Mar 30, 2005
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The stock head gasket, with new bolts can withstand about 9 PSI of boost torqued at 70ft lbs. Any higher and you're asking for trouble.

so says toyota expert mister turbine twister....

how did you reach that figure of 9psi being the limit? also, who told you to torque the bolts/studs to 70ft lbs? IIRC ARP reccomends torquing the studs to 72ft lbs.
 

antman

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Apr 6, 2005
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good judgement comes from experience.
experience comes from bad judgement.
 

shaeff

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lagged said:
so says toyota expert mister turbine twister....

how did you reach that figure of 9psi being the limit? also, who told you to torque the bolts/studs to 70ft lbs? IIRC ARP reccomends torquing the studs to 72ft lbs.


AND, if you do everything correctly, you can go higher than that. its all in the tuning. you could run 400hp off a stock headgasket, as long as you make no mistakes in tuning the car. first sign of detonation, and you're looking at another HG....

take a good long look at bishop's car...

-shaeff
 

billspreston01

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Jun 2, 2005
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my ARP's said to torque them to 80ft lbs, and I'm using a stock hg on a brand new head (well...glass beaded with allll new parts and seals) and I cleaned the s*** outta my block deck. I hope it holds more than 9psi...
 
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