4T80E/Turbo-S/C... TIME FOR A NEW THREAD?
Thread Starter
Senior Member
Posts like a Turbo
Joined: Jan 2005
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From: Atlanta, GA. USA
Originally Posted by 2000SilverBullet
Even 85 seems low.
The head bolts on my V8 are 130 ft-lbs. :?
The head bolts on my V8 are 130 ft-lbs. :?
I'll go with 80, but i am using a different tq wrench to eliminate that as a possibility.
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Joined: Jun 2002
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Go with the manufacturers specs for sure. 
The 130 ft-lb head bolts are 9/16" so yours are probably 1/2" but you can torque them to higher than 75%. They chose 75% to be safe based on torque wrench and friction variations.
Turn of the nut method is now preferred and I see even GM specs it that way in the Service Manuals. You can safely go to 85%.
Some fasteners are even torque to yield for one time use but they are made of a special metal.
You could do a simple calculation to determine turn of the nut if you knew the value of the studs yield strength and the number of threads per inch, the rest is engineering physics
The 130 ft-lb head bolts are 9/16" so yours are probably 1/2" but you can torque them to higher than 75%. They chose 75% to be safe based on torque wrench and friction variations.
Turn of the nut method is now preferred and I see even GM specs it that way in the Service Manuals. You can safely go to 85%.
Some fasteners are even torque to yield for one time use but they are made of a special metal.
You could do a simple calculation to determine turn of the nut if you knew the value of the studs yield strength and the number of threads per inch, the rest is engineering physics
Thread Starter
Senior Member
Posts like a Turbo
Joined: Jan 2005
Posts: 368
Likes: 0
From: Atlanta, GA. USA
Originally Posted by 2000SilverBullet
Go with the manufacturers specs for sure.
The 130 ft-lb head bolts are 9/16" so yours are probably 1/2" but you can torque them to higher than 75%. They chose 75% to be safe based on torque wrench and friction variations.
Turn of the nut method is now preferred and I see even GM specs it that way in the Service Manuals. You can safely go to 85%.
Some fasteners are even torque to yield for one time use but they are made of a special metal.
You could do a simple calculation to determine turn of the nut if you knew the value of the studs yield strength and the number of threads per inch, the rest is engineering physics
The 130 ft-lb head bolts are 9/16" so yours are probably 1/2" but you can torque them to higher than 75%. They chose 75% to be safe based on torque wrench and friction variations.
Turn of the nut method is now preferred and I see even GM specs it that way in the Service Manuals. You can safely go to 85%.
Some fasteners are even torque to yield for one time use but they are made of a special metal.
You could do a simple calculation to determine turn of the nut if you knew the value of the studs yield strength and the number of threads per inch, the rest is engineering physics
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True Car Nut
Joined: Sep 2006
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From: Indianapolis, IN
Can someone give me an update about where to get more info? It has almost been 20 days since the last post. I know this is aiming for the archives, but where can I read more about the finished head gasket repair and posted videos?
