With the last few vehicles that have had their head bolts replaced with ARP studs, an interesting and distressing pattern has emerged. The bolts do not have the same torque from the factory, even within the same engine or location group in the engine.
I am asking anyone and everyone to assist in the collecting of data about the engines that you work on, so that a more complete picture can be created and predictions can be made.
Using the Factory Service Manual bolt numbering from page 9-197 and pictured here:
PLEASE follow this pattern of numbering for consistency, and the following instructions to discover and report back about the breaking torque for each factory head bolt. This is very important, so thank you for doing this!
Measuring the force is fairly simple: Using your large click torque wrench (I use the $80 30 inch one from Home Depot - it clicks in both directions) set the torque to 80 lb-ft, and attempt to crack the bolt. If the wrench clicks (it should) increase the setting to 85, and try again. Continue increasing 5 lbs at a time. At the point that the bolt releases and the wrench does NOT click - that is the release torque. Make a chart of the bolt numbers according to the book's tightening sequence (I usually clean the head and write the numbers in sharpie directly on the head next to the bolt hole) and record the torque on that chart so that it can be shared in this thread with the board.
The critical ones to watch for are directly bordering the cylinders, on the exhaust side between or around cylinder #3. That seems to be the place that the torque is wildly different for some reason. I am curious to know the values on your engine because of this.
As for reporting: I would ask that you put the numbers into this thread in the following type of format, that I will quote in the next post for easy quote-and-edit pasting of the numbers.
CRD YEAR: xx
MILEAGE: xxx,xxx
BOLT TORQUE CENTER ROWS:
01: xxx
02: xxx
03: xxx
04: xxx
05: xxx
06: xxx
07: xxx
08: xxx
09: xxx
10: xxx
BOLT TORQUE OUTER ROWS:
11: xxx
12: xxx
13: xxx
14: xxx
15: xxx
16: xxx
17: xxx
18: xxx
Again, THANK YOU FOR HELPING THE GROUP!