ARP head bolt torque question
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
ARP head bolt torque question
I'm getting conflicting info from ARP. Their sheet that comes with the bolts says 65 ft-lbs using their lube. An email to them comes back saying 75 ft-lb using their lube. I know you lube or seal the threads but what about the head underside and washer underside.
Is the torque accounting for dry head and washer or lubed?
These are 12 pt 170/180 ksi head bolts. Aluminum heads.
It may not be a big issue but if you use 30wt oil, 65 becomes 85 by their spec. I just want to know if anyone is factoring in the head and washer lube or not which can make a difference in true bolt preload.THX
Is the torque accounting for dry head and washer or lubed?
These are 12 pt 170/180 ksi head bolts. Aluminum heads.
It may not be a big issue but if you use 30wt oil, 65 becomes 85 by their spec. I just want to know if anyone is factoring in the head and washer lube or not which can make a difference in true bolt preload.THX
Melting Slicks
Joined: May 2002
Posts: 2,431
Likes: 52
From: Florida
Use the lube on all friction surfaces and burnish fasteners by cycling them 4 or 5 times prior to sealing threads and torquing to final spec. You only need to loosen a half a turn the re-torque. I would use the 75ft/lbs on bolts.
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Jim
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You'll get more responses from engine experts which I don't happen to be.
Jim
Safety Car
Joined: Oct 2004
Posts: 3,923
Likes: 733
From: Youngstown Ohio
Use the lube on all friction surfaces and burnish fasteners by cycling them 4 or 5 times prior to sealing threads and torquing to final spec. You only need to loosen a half a turn the re-torque. I would use the 75ft/lbs on bolts.
Ask your question over here>>> http://forums.corvetteforum.com/forumdisplay.php?f=7
You'll get more responses from engine experts which I don't happen to be.
Jim
Ask your question over here>>> http://forums.corvetteforum.com/forumdisplay.php?f=7
You'll get more responses from engine experts which I don't happen to be.
Jim
I use this same method, and always a final torque of 75ft/lbs. (I tried 65ft/lbs. at first, but later had to retorque when the bolts loosened up.)
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Their lube is Moly and it is sustantially slicker than 30wt motor oil. The srface area between the washer and bolt head should be lubed. I always go a couple pounds over the spec. ARP can handle it and good head gaskets won't care.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
That's interesting C3 about your bolts loosening up with 10 ft-lb undertorque. Three bolts on my AFR's just loosened up when I used
30WT and went to 75. ARP now says it should have been 85 with 30Wt so I may have undertorqued. I did cycle the bolts 3 times during initial build.
They also say for Aluminum heads to only go 60 instead of 65 with their Moly. AFR recommends 65-70. I think I'll end up going 70 with the Moly lube under the heads and their thread moly sealant.
30WT and went to 75. ARP now says it should have been 85 with 30Wt so I may have undertorqued. I did cycle the bolts 3 times during initial build.
They also say for Aluminum heads to only go 60 instead of 65 with their Moly. AFR recommends 65-70. I think I'll end up going 70 with the Moly lube under the heads and their thread moly sealant.
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
I beleive Gary Ramadei had this issue with ARP as well regarding the ring gear bolt torque. He couldn't get a straight anwser from them, as everyone kept telling him conflicting different torque numbers. I guess it all depends on the person you talk to on the phone...
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
I would advise that you do not exceed specified torque levels when installing steel bolts in aluminum heads. The dissimilar metals "grab" better than like metals, so they don't require as much torque; also, the aluminum threads are not as strong. You might be better served to keep oil out of the threads and install them with some thread locker to keep the bolts from backing out.
Safety Car
Joined: Oct 2004
Posts: 3,923
Likes: 733
From: Youngstown Ohio
I would advise that you do not exceed specified torque levels when installing steel bolts in aluminum heads. The dissimilar metals "grab" better than like metals, so they don't require as much torque; also, the aluminum threads are not as strong. You might be better served to keep oil out of the threads and install them with some thread locker to keep the bolts from backing out.
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Race Director
Joined: Mar 2006
Posts: 14,112
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From: Florida
The only problem you might have with moderate over torquing with arp fasteners is possibly crushing the head gasket. The good MLS gaskets for aluminum heads are designed to move a bit within themselves, but not against the block or the head surface and the vast majority is caused by the different expansion rates of each meaterial.
As in most cases, the better the product the better the result.
Safety Car
Joined: Oct 2004
Posts: 3,923
Likes: 733
From: Youngstown Ohio
Since the head bolts go into the water jackets then no oil should be used and only a non hardening thread sealer such as ARP also has available. The oil should only be used between the bolt head and the hardened washer. Most cheaper aftermarket chevy bolts come with the sealant already on the threads.
The only problem you might have with moderate over torquing with arp fasteners is possibly crushing the head gasket. The good MLS gaskets for aluminum heads are designed to move a bit within themselves, but not against the block or the head surface and the vast majority is caused by the different expansion rates of each meaterial.
As in most cases, the better the product the better the result.
The only problem you might have with moderate over torquing with arp fasteners is possibly crushing the head gasket. The good MLS gaskets for aluminum heads are designed to move a bit within themselves, but not against the block or the head surface and the vast majority is caused by the different expansion rates of each meaterial.
As in most cases, the better the product the better the result.
