Aluminum Head torque specs????
Thread Starter
Hoon
Joined: May 2000
Posts: 718
Likes: 759
From: Krypton
Aluminum Head torque specs????
I had my original LT4 heads ported and polished. When re-assembling the engine, I decided to use ARP head studs instead of the oem bolts. My question is......What do you guys use for toque settings with head studs?? I have heard several different recommendations from various people.
ARP says that with their 7/16 SBC head studs, use 80 ft/lbs on all of the nuts (using SAE 30 oil as a lubricant).
Various aluminum head vendors recommend 70 ft/lbs on bolts or studs.
In the Corvette service manual, Chevrolet recommends different torque for the short, medium and long bolts.
I tend to trust ARP, but 80 ft/lbs sounds sounds like a LOT of torque to apply to aluminum heads. The guy at ARP said that if you use their moly thread lube, you can torque the nuts to only 65 ft/lbs and get the same clamping force as using 80 ft/lbs with SAE 30 oil (due to frictional losses).
I am using the OEM chevrolet LT4 head gasket, which appears to be a very good gasket.
I do not want to do this job a second time to replace a blown head gasket, so any advice woould be appreciated.
thanx............GSVette
ARP says that with their 7/16 SBC head studs, use 80 ft/lbs on all of the nuts (using SAE 30 oil as a lubricant).
Various aluminum head vendors recommend 70 ft/lbs on bolts or studs.
In the Corvette service manual, Chevrolet recommends different torque for the short, medium and long bolts.
I tend to trust ARP, but 80 ft/lbs sounds sounds like a LOT of torque to apply to aluminum heads. The guy at ARP said that if you use their moly thread lube, you can torque the nuts to only 65 ft/lbs and get the same clamping force as using 80 ft/lbs with SAE 30 oil (due to frictional losses).
I am using the OEM chevrolet LT4 head gasket, which appears to be a very good gasket.
I do not want to do this job a second time to replace a blown head gasket, so any advice woould be appreciated.
thanx............GSVette
Melting Slicks
Joined: Aug 2001
Posts: 2,516
Likes: 0
From: Lockport NY
Re: Aluminum Head torque specs???? (gsvette)
In the Corvette service manual, Chevrolet recommends different torque for the short, medium and long bolts.
Shoot, common sense dictates that a 3" stud/bolt will stretch more than a 2" stud/bolt when heated...Which equates to less torque on that 3" stud/bolt when hot compared to the 2" stud/bolt...*If* they're set at the same cold pre-torque...
I'd follow GM's advice...
Ok; let's hear it... :smash:
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Re: Aluminum Head torque specs???? (Rich B.)
I would go with ARP since it is their hardware. I would think that once you introduce a wild card into the OEM equipment-then their specs may not apply. I would confirm with ARP about the different lengths as I have done cast iron heads there is a difference.
gsvette: Did you pull the engine to do the head swap? Wondered if you can pull a head with studs as it seems pretty tight...
gsvette: Did you pull the engine to do the head swap? Wondered if you can pull a head with studs as it seems pretty tight...
Safety Car
Joined: Jun 1999
Posts: 3,570
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From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Re: Aluminum Head torque specs???? (gsvette)
Use ARP specs.
The factory bolts are Torque to Yield (TTY) which require a completely different procedure than regular bolts or head studs. I used the factory bolts and was not very happy with the whole TTY procedure.
The factory bolts are Torque to Yield (TTY) which require a completely different procedure than regular bolts or head studs. I used the factory bolts and was not very happy with the whole TTY procedure.
