I have never had a 55-62 235/261 block that needed an align bore. It’s really pretty rare for these early 6 motors. Yep, no changing the caps. Each block was machined with the cap in place so the caps are specific to the block. No, no need to align bore simply because you are changing cranks. My 59 Canadian 261 block has a crank out of a 56 235 in it. But I was particular when I machined the crank. The crank had been through another motor of mine so it needed a full redo. Ended up .030 on the rods and mains. Had the throws equalized, and the crank was ground at 120 degrees. Drilled the snout for a small block balancer bolt (mr gasket), then balanced. So all the specifications are spot on.

Quite a few years ago, probably back in the middle 80s, Charlie Baker described his procedure for installing the crank. I was pretty young then, and I use to call Charlie, buy parts, and have him learn me on building these motors his way. So here is a little extrapolation from my notes and an article he wrote for the TPN all those years ago.

When he had his cranks ready for install, he like to install the main bearing shells in the block and light oil on them - do not install the rear main seal yet. Lay the crank in and rotate it a few times, it should rotate nice and smooth.

Bolt the main caps and bearings on (light oil on the bearings) on and torque to 30-40 pounds, rotate. Repeat the process in 10 pound increments until 80-90 pounds. If all spins free, disassemble, remove the crank.

Clean the bearings, caps and block saddles one more time. Insert the upper bearings back in the block. Install the rear main seal. Light oil on the bearings, install the crank. Install bearings in caps, oil, install caps, torque to 30-40, rotate, repeat in 10 pound increments until 80-90 pounds. Crank should spin smoothly but with a little more force.

Remove no. 1 cap, wipe oil from journal and shell. Apply plasticguage, retorque to 80-90, no rotating. Dissemble, Read to confirm clearance is within specification. If it is, clean the journal and cap bearing, coat the cap bearing with assembly lube. Reinstall cap and torque, rotate the crank. Repeat the process for the remaking three caps.

For the rear main seal, offset it if it’s a neoprene seal, little dab of silicone on the ends, smear the rear seal with assembly lube.

Spin crank, should spin smooth but with the same force as before with the main seal installed. If so, last thing is to put a dial indicator on the crank flange and move crank back and forth. Should be .003-.008. If so, you are done!

I have used charlie’s Procedure on every 235/261 I have built since probably 1984 or so, nearly 50 of them, purely as a hobbyist. Not one single failure. Not one time was an align bore required. My motors have hung in there for years. One in my garage was the first one I did using Charlie’s procedure, and other things he liked to do to these motors. I beat that motor unmercifully for years. Still ran great when I took it out for the bigger 261 a couple of years ago. The new 261, no issues (even with the gmc truck rods) and over twenty runs down the dragstrip at the trifive nationals over the last couple of years - it’s a street car and street motor.

Mike

Last edited by mdonohue05; 04/19/18 11:30 PM.