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Neil Harvey Neil Harvey is offline
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Join Date: May 2004
Posts: 438
I read on the other forum that the use of moly grease is the cause. Not to challenge this, but I have never seen this before. The moly grease or the ARP grease is there to reduce friction so the torque values or nut to thread engagement does not get affected by friction.

I think the std ARP studs are made from a chrome moly steel, 8740 I think. The steel gets some heat treatment to increase the tensile strength. The use of this material is based upon their most common fasteners. It was never meant as a replacement or straight conversion of the Porsche type. As "Rennsport Steve" suggests, the use of the factory studs is probably the better solution, unless you are prepared to do some checking prior to installation.

Whenever you decide to use something like an ARP stud, you should be pre checking its behavior when installed. Installed height, stretch etc., at different torque values. If you use torque values only, you really have to do some checking to see if you achieve the same stretch on each stud. Otherwise you could have different values at each stud. The clamping load is what you are after knowing to be the same on each stud and at an amount acceptable.

Best way is to tighten a stud with something in between the case and the nut. You can then measure the stretch verses the torque valve you wish to use. Just using 38 ft/lbs could net different clamping loads on each stud. Maybe 30 lbs is enough. maybe you need to increase the value. You can then make sure the stud is not pulling out of the case, the cylinder head isn't collapsing around the washer platform. Too much torque and not enough stud stretch could stretch the threads in the case or collapse the heads. Then the amount of torque applied will not go onto stretching the stud that puts the whole assembly under tension and hold everything together tight.

Make sure the heads are the same height, the case widths are the same from front to rear of each half. All the basic stuff should be checked also.

Seems like a simple thing but there are some important points that need checking and understood.
Old 04-03-2018, 04:07 PM
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