ARP Head Stud torque specs needed
I have just completed a 2.5 hour tour of the Earnhardt-Childress Racing Engines shop in Welcome, North Carolina.
During that visit I had a discussion with their R&D Shop Foreman about cylinder head attachment for the LS engines. ECR has determined that the LS heads move around on the engine, even when naturally aspirated, when the cylinder heads are torqued using the method shown above. What they now do using ARP 12mm studs that have been turned down to 11mm outside of the threads that go into the block, is to torque the studs 85 lb-ft. Then they loosen the nuts completely, reapply ARP's thread lube, and retorque the studs to 85 lb-ft. again.
They stated that the retorquing eliminates head movement, and shows a significant improvement in gasket sealing and a more uniform distribution of the clamping load across the gasket. The important thing to take away from the information that ECR Engines provided is - AFTER YOU HAVE COMPLETED YOUR INITIAL TORQUING OF YOUR CYLINDER HEAD STUDS, REMOVE THE NUTS, APPLY A FRESH COATING OF THREAD LUBRICANT - BEING SURE YOU DO NOT GET ANY LUBRICANT BETWEEN THE WASHER AND THE CYLINDER HEAD, AND RETORQUE THE NUT.
During that visit I had a discussion with their R&D Shop Foreman about cylinder head attachment for the LS engines. ECR has determined that the LS heads move around on the engine, even when naturally aspirated, when the cylinder heads are torqued using the method shown above. What they now do using ARP 12mm studs that have been turned down to 11mm outside of the threads that go into the block, is to torque the studs 85 lb-ft. Then they loosen the nuts completely, reapply ARP's thread lube, and retorque the studs to 85 lb-ft. again.
They stated that the retorquing eliminates head movement, and shows a significant improvement in gasket sealing and a more uniform distribution of the clamping load across the gasket. The important thing to take away from the information that ECR Engines provided is - AFTER YOU HAVE COMPLETED YOUR INITIAL TORQUING OF YOUR CYLINDER HEAD STUDS, REMOVE THE NUTS, APPLY A FRESH COATING OF THREAD LUBRICANT - BEING SURE YOU DO NOT GET ANY LUBRICANT BETWEEN THE WASHER AND THE CYLINDER HEAD, AND RETORQUE THE NUT.
How does a head that's doweled (roll pins) to the block move around? Agree w/ better gasket sealing, but, other than thermal expansion, how can it move? Would also limit the 85 ft/# suggestion to those using studs... or on iron blocks when using bolts. Bolts add a torsional load to the block threads where studs do not.
Old thread, but, needed comment.
On The Tree
Joined: Dec 2004
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From: Northville, Michigan
How does a head that's doweled (roll pins) to the block move around? Agree w/ better gasket sealing, but, other than thermal expansion, how can it move? Would also limit the 85 lb.-ft. suggestion to those using studs... or on iron blocks when using bolts. Bolts add a torsional load to the block threads where studs do not.
Old thread, but, needed comment.
Old thread, but, needed comment.
According to Earnhardt-Childress Racing Engines both assumptions are bad.
Haven't assumed. Am sure that lifted, spread, opened, gap increase between head & block...etc. was meant in the ECR post, but, not used. The term moved is vague. I noted thermal expansion. There can be no lateral movement between dowels other than from the thermal expansion occurring over the entire head. This has nothing to do w/ head stud torque.
This entire bolt torque thread is all over the place & can cause someone w/ an aluminum block to damage their block threads. If using bolts in aluminum, do not over torque.
There's only one main kit for the (factory) LS, #234-5608. I had to call ARP and verify this, as that PN shows "Chevrolet Small Block LS1 cast iron Main Stud Kit" (the tech I talked to said he's been after their web dept to change that description for years). The sheet I have (and it's current) shows 60/50 on the 10mm bolts and 20 on the 8mm bolts. Not saying it won't work, but 90# is a huge increase from 60/50# and could possibly deform the bores...
I think also at some point the stock cylinder head has not enough thickness to take advantage of this higher torque. The aftermarket heads have thicker deck surfaces and can take more clamping force. I have an ERL block and they recommend another 10 ft pounds or so on after market heads. On the ZR1 motor the heads/block have a 12 mm stud and I think are like 120 pounds of torque - I am sure that is a lot of fun to do in the car.
Standard ARP studs Sorry for the confusion! Didn't know there were two levels now. The 234-4313 and 234-4314 sets are higher strength CA625 and over $1000 a set! My standard studs 234-4317 are in the $4xx range.
I talked the ARP tech support and he said "100 ft/lb from a set from 2010, I don't think so... Those are only for the the high hp race studs. (CA625)" He said they actually lowered the torque on the standard studs from 80 to 70 because folks kept lubing the bottom of the washers causing the nut to get way tighter that it was supposed to and snapping off studs in the block. Sounds like you could do 80 if the washers and head mating surfaces are clean and dry.
Another tip he said was to rough up the bottom of the washers with some low grit sandpaper to give them extra bite on the head to prevent rotation.
Posting this to prevent folks from snapping off head bolts... 70 ft-lbs official from ARP.
I talked the ARP tech support and he said "100 ft/lb from a set from 2010, I don't think so... Those are only for the the high hp race studs. (CA625)" He said they actually lowered the torque on the standard studs from 80 to 70 because folks kept lubing the bottom of the washers causing the nut to get way tighter that it was supposed to and snapping off studs in the block. Sounds like you could do 80 if the washers and head mating surfaces are clean and dry.
Another tip he said was to rough up the bottom of the washers with some low grit sandpaper to give them extra bite on the head to prevent rotation.
Posting this to prevent folks from snapping off head bolts... 70 ft-lbs official from ARP.
I don't know how old this thread is but I just ordered headstuds for my Ls1 Gen 4 and the instructions state 30 1st pass,60 2nd pass ,90 3rd pass and 28 on the small bolts? I wish they would make up my mind,I guess I'll have to call them.
Cmon man, you don't know how old the thread is? Just look at the last post and that'll tell you..
I haven't seen BennyB on here in ages but I've used that same torque 30,60,90 for the ARP studs on the 427 and 370.
I haven't seen BennyB on here in ages but I've used that same torque 30,60,90 for the ARP studs on the 427 and 370.
I'll say this: It depends on what ARP fasteners/studs you're using. According to ARP, the ARP 2000 stuff has a different torque value than their other stuff. FWIW-I've NEVER had them tell me 80lbs.....
