Main cap torque
 

When you have Pro- Gram Engineering splayed main cap's installed, what is the recommended torque spec's on the main studs and outer bolt's. Your help is greatly appreciated. Thanks Rusty

Torque is defined by the bolt, not the material that it's clamping. I would follow what ever the bolt manufacture recommends.

Withinreason. The Main Webs can only handle so little hoop stress.

Whether you're clamping iron, steel, or diamond, I wolud stay close to the Factory TQ limit for factory blocks. Aftermarket block material MUST be better (higher tensile strength, probably same modulus) to warrant a high torqueset.


If not heeded, then my opinion is the crank will scrape the macadam at WOT.

Hey Rusty we have 95 on main ARP studs and 85 on grade 8 splay bolts in the stock block with program caps

Brian

I would ask your machine shop what spec they used to do the machine work.

I have ARP studs.110 lbs on all three 4 bolt caps. 140 lbs on the rear...

Thanks Guy's Your help is greatly appreciated. Thanks again

Also depends on the type of lube used

Absolutely agree with this...Also jm455HO's comment on type of lube used applies as well.
Both would be "'best practice" advise IMO ! I'll add that same type/brand fasteners should be used as well. Generally not a good idea to exceed fastener manufacturer's torque specifications.

Yes. Let's go through the worst-case example: A fella is told to Torque the 1st 4 Main Studs to 130 ft-lbs using a slippery lube. The Main Saddles would build up a hoop stress that exceeds the Main saddle width, and the hoop cracks early in life. Such a Spec makes me angry.

I am no expert, can you please explain what you mean by "hoop stress".
Thanks.

Factory bolts have a coarse thread, while studs have a fine thread on the end the nut goes onto. So I guess it would take much less torque to put the same load on the threads in the block. To stretch the studs the correct amount (whatever that is) I guess would take a bit more load than a factory bolt. Overall I would think the torque setting would be lower than for factory bolts but I would follow stud manufacturers specs (as should the machinist IMHO).
Just my thoughts/ideas.

Hoop Stress is the Mechanical engineering analysis performed to calculate the tensile load that the material can handle, and how much load you are putting the material in tension.
The hoop of metal is a ring of metal, like a nut, that can burst.

We all need to know that the Torque wrench is capable of over-loading the hoop of metal known as the Main Saddle threads.

Good-N-tite is not acceptable.

Torquing until it gives and backing off an 1/8th turn is purely a humorous corollary to knowing a fell busted the hoop while torqueing.

Over-Torquing ; turning the TQ Wrench while the reading sits at 100 Ft-Lbs for 3/4 to 1 full turn or more is another way of over-stressing the Fastener System so that a Ping transient is sufficient to bust the hoop.

Sure seems like the most important aspect is to replicate the torque value the machine shop was at when they honed the mains. Additional clamping force will deform them. Next thought was this should be discussed with the shop before work begins.