Iím in the process of rebuilding an AC G-262 gas engine. The connecting rods use a marsden type self- locking nut. The AC specs for rod torque is 40 to 45 ft-lbs. The engine I am working on had 1 rod with the wrong nuts on it. It had cotter style nuts on it but the bolts for the connecting rods are not drilled for installing cotters. I have also rebuilt Buda B230 gas engines. The rods use a castellated nut with cotters and the torque spec for these is 50 to 65 ft-lbs. Why is there such a difference in torque specs? Does the AC engine use a lower grade of rod bolt?
I found a self-locking nut called Flexloc 21FC624. These appear to be similar in nature to the original AC nut type but are cadmium plated so they may not require as much torque as a dry nut. Has anyone out there found a good self-locking nut that may be used and if so, what torques do you use.