Metal Head Gasket and Torque Specs

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SupraTrbo89

Member
Sep 21, 2006
229
3
18
West Chester, PA
My 89 MK3 turbo is currently in the shop and the head is off and at the machine shop. I am having the head resurfaced and I am wondering about the block. I stopped into the shop today and spoke with the mechanic and checked out the block. The mechanic put a straight edge across the block and it is 100% flat. Upon closer inspection there are VERY small impressions in a few areas from the copper around the rings/water jackets from the stock head gasket. Due to the fact the block is straight do you think I can get away with a MHG? Are some MHG brands more forgiving than others? I was thinking Titan 1.4MM - after checking with the machine shop to see how much they shave off but I'm not anticipating much.

Also, the stock head gasket blew from the water jacket into cylinder number 6 because the copper around the water jacket separated from the gasket material. The car was still drivable and actually drove stong after it warmed up, but I wanted to have the work done before it got worse. I am pretty sure the head gasket was on its way out when I bought the car. The motor in the car is JDM as the previous owner blew the original.

Lastly, I purchased a set of ARP head studs and the directions in the box say torque to 90lbs. I have read people torqueing to 75 or 80, but not as high as 90? What are your recommendations?

I have always run stock boost in the car and my goal is 10psi.

Thanks for the help
 
supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
4,231
36
48
Atlanta
Not sure if you were asking if you could use an MHG without surfacing the block.
If you were, then no. Have the shop deck the block with a fresh cutting bit, so you get a very smooth surface.
And have the lower rear timing cover installed on the block when it's done. The cover must be shave as much as the block, so that it's ALL flush.
 
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SupraTrbo89

Member
Sep 21, 2006
229
3
18
West Chester, PA
Yea....I was asking if you can get away without resurfacing the block. Mechanic said the labor goes from 12-13 hrs to 20-25hrs plus the cost of the decking at the shop....at a $100 an hr it bumps up my $2,000 job to a $4,000 job. At $4,000 I'd rather go 1jz, but at this point its too late.

I talked to Aaron at Driftmotion and he said if I use a stock head gasket its only a matter of time befofe it eventually blows again.

Anyone run a stock head gasket with a resurfaced head and ARP studs at 10 psi reliably without decking the block if its not warped?
 
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Dan_Gyoba

Turbo Swapper
Aug 9, 2007
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Alberta
www.gyoba.com
FWIW, I ran a Toyota stock HG with ARP studs in my '89. (Didn't get the block decked, but I did have the head surfaced appropriately.)

I ran that on a stock turbo at 13PSI for one year and a 60-1 turbo at 18 PSI for 2 years. Spearco replica IC, Lexus/550s, Aeromotive AFPR. 1987 TCCS, no tuning devices.

3 years, 45,000km, no problems. At the end of the third year, I developed rod knock, but the HG is still fine. The car never lost any coolant, ever.

I'm not the most aggressive driver out there, but I didn't drive the Supra as a commuter car, I drove it like I wanted to have some fun with it, so it saw high boost most drives, though redline was less frequent.

Basically, it CAN be done, it's going to depend on how you drive, how hot you run it, and if you take care of the cooling system. I also know that Reg Reimer ran his 7M-GTE on stock head bolts (at 72 ft-lbs) and a stock Toyota HG at 21 PSI on the HKS turbo with VPC, F-CON, Lex/550s and a Techtom ECU. To the best of my knowledge, that factory HG is still the one in the car now.
 
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SupraTrbo89

Member
Sep 21, 2006
229
3
18
West Chester, PA
Dan_Gyoba;1957485 said:
FWIW, I ran a Toyota stock HG with ARP studs in my '89. (Didn't get the block decked, but I did have the head surfaced appropriately.)

I ran that on a stock turbo at 13PSI for one year and a 60-1 turbo at 18 PSI for 2 years. Spearco replica IC, Lexus/550s, Aeromotive AFPR. 1987 TCCS, no tuning devices.

3 years, 45,000km, no problems. At the end of the third year, I developed rod knock, but the HG is still fine. The car never lost any coolant, ever.

I'm not the most aggressive driver out there, but I didn't drive the Supra as a commuter car, I drove it like I wanted to have some fun with it, so it saw high boost most drives, though redline was less frequent.

Basically, it CAN be done, it's going to depend on how you drive, how hot you run it, and if you take care of the cooling system. I also know that Reg Reimer ran his 7M-GTE on stock head bolts (at 72 ft-lbs) and a stock Toyota HG at 21 PSI on the HKS turbo with VPC, F-CON, Lex/550s and a Techtom ECU. To the best of my knowledge, that factory HG is still the one in the car now.
Click to expand...

Your driving habits sounds very similar to mine and I only put about 4k miles on my car per year. As far as my cooling system goes everything is brand from the hoses/thermostat/water pump and I have a new Fluidyne radiator. As far as mods go I'd like to run what you were running on the 60-1. I didn't know you could go 18psi on stock pistons though??

Also, is there any break in period with the car after the head resurfacing/arps and stock head gasket are in?
 
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