ARP head bolt torque?
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
I used the torque-angle method. 22 lb. ft. then an additional 67º for the short bolts and 80º for long and intermediate bolts. Sealant on the threads as 12SCNDZ said and oil under the bolt head.
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
Originally posted by AsianSensation
Hey Rob, I thought the torque-angle method is for TTY head bolts only.
Hey Rob, I thought the torque-angle method is for TTY head bolts only.
As noted in a thread a while back, all bolts stretch-not just ones noted as TTY. If you were to be positively accurate, you would measure the bolt stretch (which is the basis of TTY). Obviously, the head bolts cannot be measured, since they are in a "blind" application. From what I have read, the torque-angle method is the next best accurate way to tighten them.
I know we have plenty of engineers poking around in this forum (LOL) and would not mind hearing what they have to say.
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
Originally posted by 96UltraZ28
Wouldnt the TTY method be wrong on ARP bolts/studs? Since they are stronger they shouldnt stretch as much as the stock bolts which should cause you to overtighten the ARP bolts.
Wouldnt the TTY method be wrong on ARP bolts/studs? Since they are stronger they shouldnt stretch as much as the stock bolts which should cause you to overtighten the ARP bolts.
Here is some additional info from Oliver (the company that makes those expensive rods):
Q: Why can't your bolts be torqued?
A: Any bolt can be torqued. The question is: will using the torque method of tightening a bolt give you good, repeatable results? This is important because at top dead center of the exhaust stroke, the piston wants to continue right up through the cylinder head and the crankshaft wants to pull the piston back down the cylinder walls. At high RPM this load can exceed 18,000 pounds of pull on the cap. It is the job of the bolt(s) to provide enough clamping force to keep the cap from separating from the tower of the rod. The problem is a torque wrench only measures friction not clamp load and every time you tighten the bolts you change the mating surfaces of the threads and where the head of the bolt contacts the rod. This changes the amount of friction that must be overcome to correctly tighten the bolt. What this means is if you tighten the bolts to the same torque level, you will have a different clamp load on the bolts each time. Because of the large potential variations in the actual clamp loads achieved by using torque, we strongly recommend against using torque.
Q: Why use torque and angle?
A: We didn't invent this. It has been used by automobile and diesel manufacturers and in the aerospace industry for many years because it is much more accurate than using torque to tighten bolts. Torque and Angle uses the pitch of the threads as a good, repeatable reference for properly tightening the bolts. For example, if the bolt has a 7/16" 20 threads per inch pitch, then one full (360 degree) turn of the bolt will move the bolt exactly .050" (fifty thousandths of an inch), or 36 degrees of turn will move the bolt exactly .005" (5 thousandths of an inch). We have a specification for Torque and Angle for all of our bolts, no matter their size (5/16", 3/8", 7/16" etc.) and our specs are all derived from the pitch of the specific thread on each size of bolt.
Q: After using torque and angle, shouldn't the bolts be replaced?
A: Don't confuse torque and angle with torque to yield. Torque to yield stretches the fastener past the point of where it will not return to its original length. This weakens the bolt and makes it unusable for repeated tightening. When you use the torque and angle method according to our directions, you will stretch the bolts to 75% of yield. This allows the bolts to be used repeatedly without fear of weakening them.
A: Any bolt can be torqued. The question is: will using the torque method of tightening a bolt give you good, repeatable results? This is important because at top dead center of the exhaust stroke, the piston wants to continue right up through the cylinder head and the crankshaft wants to pull the piston back down the cylinder walls. At high RPM this load can exceed 18,000 pounds of pull on the cap. It is the job of the bolt(s) to provide enough clamping force to keep the cap from separating from the tower of the rod. The problem is a torque wrench only measures friction not clamp load and every time you tighten the bolts you change the mating surfaces of the threads and where the head of the bolt contacts the rod. This changes the amount of friction that must be overcome to correctly tighten the bolt. What this means is if you tighten the bolts to the same torque level, you will have a different clamp load on the bolts each time. Because of the large potential variations in the actual clamp loads achieved by using torque, we strongly recommend against using torque.
Q: Why use torque and angle?
A: We didn't invent this. It has been used by automobile and diesel manufacturers and in the aerospace industry for many years because it is much more accurate than using torque to tighten bolts. Torque and Angle uses the pitch of the threads as a good, repeatable reference for properly tightening the bolts. For example, if the bolt has a 7/16" 20 threads per inch pitch, then one full (360 degree) turn of the bolt will move the bolt exactly .050" (fifty thousandths of an inch), or 36 degrees of turn will move the bolt exactly .005" (5 thousandths of an inch). We have a specification for Torque and Angle for all of our bolts, no matter their size (5/16", 3/8", 7/16" etc.) and our specs are all derived from the pitch of the specific thread on each size of bolt.
Q: After using torque and angle, shouldn't the bolts be replaced?
A: Don't confuse torque and angle with torque to yield. Torque to yield stretches the fastener past the point of where it will not return to its original length. This weakens the bolt and makes it unusable for repeated tightening. When you use the torque and angle method according to our directions, you will stretch the bolts to 75% of yield. This allows the bolts to be used repeatedly without fear of weakening them.
Last edited by shoebox; Feb 5, 2004 at 07:37 PM.
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
Originally posted by TUFF LT1
Not trying to jack your thread, but do all of the bolts need sealant? Isn't there two bolts per head that don't go into the water jacket?
Not trying to jack your thread, but do all of the bolts need sealant? Isn't there two bolts per head that don't go into the water jacket?
Registered User
Joined: Nov 2002
Posts: 338
From: Dayton Ohio
Thanks Shoebox, I was just wondering because I noticed that when I took my stock bolts out of the heads on my 95 two of the bolts on each head didn't have any sealant on them. So I just put lubricant on the ARP bolts that went the same place as the stock bolts that didn't have sealant on them. Just wanted to reassure myself that it was gong to be ok like ther. Thanks again.
Registered User
Joined: Oct 2001
Posts: 534
From: Avon, IN, USA
I used the angle method when I put my heads on , but I think it is a bunch of crap. I see how, in theory, you can get the bolt to stretch exactly how you want it, but you still have to use a torque measurement to get a starting point for the angle. If that torque is not accurate (it is just friction as mentioned above) then the angle you add to it still won't be accurate.
Dustin
Dustin