I think I answered my own question, I believe the rods would need to come off since the pistons can only come out through the head side of the motor as I believe there is a stop on the crank side.  I guess if the crank was interchangeable would there any benefit to one over the other as long as both are in good shape?

Thanks for confirming Bob!  I’ll utilize the better of the two cranks then.  I will do as you suggest and take some measurements and compare against the tolerances in the service manual to make an informed decision.

I will.  Here are a few pictures of my fuel reclaimer set up as well as my capacitor condenser replacement.  Since those motor was initially going to scrap and I got it for $30 so I have been using it as a bit of test motor based off information I have gleaned off this wonderful site.

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aquasonic

Sooo, I’ve run into a bit of an issue.  When I split the 1955 case the rod knock was worse than I thought, and the upper cylinder had a large score.  After some honing I have it usable but the end gap on the rings is at .020 and the manual lists a top limit at .017.  The lower cylinder is at .016 so just in spec.

The question is could I modify the 1961 block to work on the 1955 motor.  It looks like I need to plug the thermostat holes on the block, and drill one new cooling hole.  I need to reuse the 1955 head but it looks like the holes line up as do the holes on the exhaust leg.  Everything else looks like it will line up (see pdf attached below with notes and photos).  The 1961 cylinders are in great shape and well below the upper end gap limit. Is there anything else I am overlooking? It looks like the starter mounts will bolt on and the intake bolts also match up.

If this works, I need to get three broken exhaust bolts out add a little green paint and I hopefully have a great runner.

I appreciate any insights.

Regards,

Jeff

Thanks for your input and fleetwin and I appreciate the offer for the crankcase, I may take you up on it if this project hits a dead end;) I was able to extract and retap the 3 broken exhaust bolts and drill out the water passage last night, see photo.  I also ran a small zip tie through all the water passages to confirm where they went and as far as I can tell the only differences were the thermostat passage and the undrilled passage.

Great idea to do a test run of the water jacket before I assemble everything to confirm I didn’t miss anything.  My next step is to fill in the thermostat water passage with epoxy.  Once that is done I can reattach the exhaust cover and head and will run water through it to see if I missed any passages.  If water goes in inlet and out exit and exhaust and cylinders stay dry I can mount the assembly to the exhaust leg and test again to see if any issues crop up there. I’ll report back when this gets done.

I looked at the 1961 base gasket and it looks like the only difference is the size was reduced for the water inlet from the water pump and there was some additional casting around the drive shaft in 1961, so I will need to stick with the 1955 style base gasket.  See exhaust leg pdf for a comparison.

Jeff