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Proper Torque procedures RX and Apex Motors

ARP's 10mm 170,000/180000psi tensile strength stud torque (based on 75% of yeild) is listed as 54 ft. lbs. with 30 weight and 42 with moly. That works out to 72 ft. lbs yeild with oil and 56 with moly. That doesn't take into account the fact that we have aluminum blocks that like to expand, lengthening the stud even more. Not to mention the threads in the block. We were definitly pushing it at 60 ft. lbs with oil.
 

Thomas800 said:
ARP's 10mm 170,000/180000psi tensile strength stud torque (based on 75% of yeild) is listed as 54 ft. lbs. with 30 weight and 42 with moly. That works out to 72 ft. lbs yeild with oil and 56 with moly. That doesn't take into account the fact that we have aluminum blocks that like to expand, lengthening the stud even more. Not to mention the threads in the block. We were definitly pushing it at 60 ft. lbs with oil.
Click to expand...

Did you draws straws for who got to pull on the wrench? 60lbs - that took some plums...
 
I had a conversation with a tech at ARP last week for about a hour when I was placing an order. Bottom line was a 10mm ARP stud (190,000 tensil) is good for 60 lbs. with ARP moly lube but due to the expansion rate of aluminum the head will grow and probably pull the threads out of the block if pulled that tight, therefore he recomended 45lbs. with ARP lube.
I have a question, my sevice manual shows the torque procedure as follows:
Studs 1+2 (center of head) 1st 14 lbs. 2nd 121 degs
Studs 3-6 and 8+9 1st 14lbs 2nd 105 degs
Studs 7+10 (cap nuts mag side) 1st 14lbs. 2nd 140 degs. Where are we getting these other procedures? :flag:
 
Hi TWIN TURBO. Kind of uncharted waters for torque when people started with the ARP studs in this motor. The follow up procedure Ted brought up is fairly common in my part of the world, obviously with different torque values. If you are who I think you are, you have an extensive automotive background. What do you do, or suggest? So the 10mm ARP studs are 190,000psi? Maybe the 60 with oil was safer than it appeared.
Thanks
 
Thomas800 said:
Hi TWIN TURBO. Kind of uncharted waters for torque when people started with the ARP studs in this motor. The follow up procedure Ted brought up is fairly common in my part of the world, obviously with different torque values. If you are who I think you are, you have an extensive automotive background. What do you do, or suggest? So the 10mm ARP studs are 190,000psi? Maybe the 60 with oil was safer than it appeared.
Thanks
Click to expand...

I have heard of guys pulling threads out of the block at 52 ft. lbs.

I would not go over 42 ft. lbs. or should I be gramatically correct and say lb. ft. :-o
 
Hi Tom and Ted,
I agree with both of you. Even "IF" you were able to pull the studs to use Teds number of 52lbs when the engine comes to temperature it could pull the threads at that time.
I use 45 lbs. with ARP lube max. But what really bothers me is Yamaha is useing different stretch on the studs, rest assure there is a reason. My guess is head temps or the density thus the expansion vary across the cylinder head and the studs are engineered to stretch accordingly. No doubt the ARP studs have more clamp force, were pulling them all down the same amount. 12 mm studs are overkill. If you loose head gaskets with 10mm ARP studs better do some re-engineering.
Don't know who I am Tom, my wife says cars and engines are my Life, she's probably right. :flag:
 
TWIN TURBO said:
Hi Tom and Ted,
I agree with both of you. Even "IF" you were able to pull the studs to use Teds number of 52lbs when the engine comes to temperature it could pull the threads at that time.
I use 45 lbs. with ARP lube max. But what really bothers me is Yamaha is useing different stretch on the studs, rest assure there is a reason. My guess is head temps or the density thus the expansion vary across the cylinder head and the studs are engineered to stretch accordingly. No doubt the ARP studs have more clamp force, were pulling them all down the same amount. 12 mm studs are overkill. If you loose head gaskets with 10mm ARP studs better do some re-engineering.
Don't know who I am Tom, my wife says cars and engines are my Life, she's probably right. :flag:
Click to expand...

My number is 38 with stock studs and 42 with ARP.
 
guys over torquing not only runs the chance of pulling threads but it also distorts the cylinders. you will not have perfect cylinder seal.
 
While I agree that over torqueing is not a good idea, I don't believe there to be any noticable amount of bore distortion on these particular motors. The stud pull is on the water jacket, which is a seperate entity from the cylinders. If the bores were attached to the water jackets, I would agree,but they are not. We have intentionally ran our motor overtorqued, for reasons I have mentioned in previous posts. Our leakdown has always been about 1/2% to not readable. I'll be the first one to admit that I have been lucky with the overtorque, not pulling the threads. Follow Teds recommendation. ;)!
 
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