Post by 1ol74charger4me on Jan 17, 2016 22:43:14 GMT -5
Sorry. My wife says all the time I am meticulous about everything except something that involves numbers. I would go .0006 if a boring bar or .0008 if on a tight tolerance machine. Your machinist is surely thinking the same .0006. .006 would almost be enough to slide the blade of a knife in. There would be quite a bit of piston "rock" with that kind of a spec.
Perfect Circle is probably a cast ring which is probably good enough for your build.I think I would classify those pistons the same as a hypertechnic with being cast but having some qualities of a forged. They may have been picked because most 340s came with forged pistons but not the 73.
If you can, at least find new stock bolts for the rods. Many have found that the rod bolts for a small block Chrysler have a life of 5 cycles of tightening. They stretch each time and after 5 cycles are no longer able to tolerate the stretching and give a false torque reading. This was explained by a Chrysler tech that actually ran the tests to determine the torque values and life of the bolts in these motors. After the 5 cycles you are actually overtightening the bolts even with a correct reading and crushing the bearing which negates all the work you just did resizing the rod end and really setting up the motor up to fail. For example; the rod bolts were tightened to initially size the rod end, then loosened to fit it to the crank and tightened again. 2 cycles. Later you took it apart and then put the rod together to resize. 3 cycles. Then most people will assemble the motor and Plastigage it. 4 cycles. Final assembly. 5 cycles. If the motor has been taken apart any other time and reassembled the rod bolts are done. Another rule of thumb is that the process of taking the rod bolts out out and putting them back in changes the position of the bolt in the rod and will give a false torque reading because you have changed its area of stretch. Many have found these rods to live way beyond expected limits but they believe the rod bolt is critical. Just some info I have picked up.
Perfect Circle is probably a cast ring which is probably good enough for your build.I think I would classify those pistons the same as a hypertechnic with being cast but having some qualities of a forged. They may have been picked because most 340s came with forged pistons but not the 73.
If you can, at least find new stock bolts for the rods. Many have found that the rod bolts for a small block Chrysler have a life of 5 cycles of tightening. They stretch each time and after 5 cycles are no longer able to tolerate the stretching and give a false torque reading. This was explained by a Chrysler tech that actually ran the tests to determine the torque values and life of the bolts in these motors. After the 5 cycles you are actually overtightening the bolts even with a correct reading and crushing the bearing which negates all the work you just did resizing the rod end and really setting up the motor up to fail. For example; the rod bolts were tightened to initially size the rod end, then loosened to fit it to the crank and tightened again. 2 cycles. Later you took it apart and then put the rod together to resize. 3 cycles. Then most people will assemble the motor and Plastigage it. 4 cycles. Final assembly. 5 cycles. If the motor has been taken apart any other time and reassembled the rod bolts are done. Another rule of thumb is that the process of taking the rod bolts out out and putting them back in changes the position of the bolt in the rod and will give a false torque reading because you have changed its area of stretch. Many have found these rods to live way beyond expected limits but they believe the rod bolt is critical. Just some info I have picked up.