Reply To: TN 28 total rebuild

[Mumbles]

Hey, hold on. Something isn’t right here. Before you go to a machine shop, lets do a little bit of back tracking here.

In your opening post, you mentioned you got new parts for your rebuild. They were a new crank, pistons, rods, rings, wrist pins, gaskets, etc. Were these parts brand new original parts or new to you parts from another used donor motor? I’m just wondering because it can make a difference. Also, why would you want to replace all of the internal moving parts? If they were worn or damaged beyond repair, the block should show similar signs of wear or damage.

You can check the crank for free running by lightly oiling its main bearings and putting the two case halves together. any binding here and you can suspect your crank might be bent.

Also, try loading each piston individually with its rings and install it into its respective cylinder one at a time. Don’t forget to oil it. A certain amount of drag will be felt with new rings in a freshly honed cylinder but any sign of tightness or excessive drag means something aint right.

After seventy years or so of use, the cylinders have probably worn to a taper shape, wider at the top and narrower at the bottom. The minimum end gap of the new rings has to be checked at the narrowest area of the cylinder they will see, which is below the intake and exhaust ports in the relatively unworn area of the cylinder. Setting the end gap of your new rings at the top of the cylinder may cause binding as the motor is turned over.

Double check, triple check your work as it’s probably something really simple causing the issue. Chances are, the machine shop might not have the time to be able to figure it out or want to work on it either.