agreed Cab.
i was wondering what the OP got for a measurement on the big end. [if he measured it as was described by the stretch and torque he mentioned]
I haven't used torque for so long, I can't remember any measurements. I use an angle gauge, then measure stretch. The big ends check fine. If it takes more torque to achieve proper stretch on any given bolt, it shouldn't affect the big end distortion. Stretch is an indicator of clamping force. If the stretch is within spec, the clamping force should be equal regardless of how much torque it took to achieve it. Variations in the rolling of the threads during manufacturing can affect torque requirements.
Cab : "I measured the ARP 2000 rod bolt stretch on a set of Scat 7.100 long rods with the Mopar big end today, I had to call Scat to try and get their recommended stretch and torque recommendations on thses bolt( 1.800 under head bolt length, 7/16 bolt diameter. No luck so i called the machine shop that I had pin fit these rods to the wrist pins in the pistons I'm going to use and had them check the rods for roundness and fit on the I.D for the rod bearings, they didn't return the instructions that came with those rods so I called then 2nd. They had to look and called me back and siad they didn't find the original sheet but looked on line at Scat site and came up with 70 Ft. lbs. with ARP lube and no longer than .0060 stretch.
My message is I saw around .0032 rod bolt length variances on these rod bolts with no load, I torque them all to70 Ft. Lbs. and that stretched them between .0041 up to .0053
I'm thinking I will loosen several of them tomorrow and retorque them up to 75 Ft. lbs. and see if that helps getting them closer to .0057 up to .0060
"......Cab
i think my old noodle is finally figuring this out. [torque plus stretch] i hope........
he!!, back in my junkyard days, when my partner [R.I.P. Bill.
] and i built engines, we didn't know any more than to mic the crank, measure the inside of the caps with bearings installed, then use plastigauge to double check when the bolts/nuts were tightened. we didn't even calibrate the torque wrenches we were using !
fast forward to today, [50 years !
] it's a whole new science, so i haft'a learn new tricks, and unlearn my bad habits.
thank you guys for being so patient with such a doofus as i have shown myself to be !
