engine won't turn

I have no idea whether or not this applies to an 8N, but when I was about 17 years old (many years ago) I attempted to overhaul a Chevy 6 cylinder engine. When I reinstalled the pistons I didn't pay any attention to insuring that the notch on the front of the pistons was pointing toward the front of the engine. I installed a couple with the notches facing the rear and the rest with the notches facing the front. When I torqued the rod caps, the crankshaft was impossible to turn. If I left the caps a little bit loose, the crank turned, but when I torqued them to the specified torque, the crank would not turn. Eventually, I pulled the head, noticed the notches, turned the pistons, re-torqued the rod caps, and the crank turned okay.

Is it possible that this could be somehow related to your problem?

Good luck,

Tom in TN

When you say "won't turn over", exactly what do you mean? Starter won't turn it over or you can't spin the crank by hand with the plugs out? If the latter, you may have a broken ring, egg shaped cylinder, wrong end gap, etc.

Main bearing caps and rod bearing caps must be matchmarked and go back in exactly the same place with the same orientation they had. That is, the entire piston/rod assembly must go back in the same hole, the caps must meet the block or rod exactly as they did before. If you did not do this, the rods will have to be resized and or the block will have to be align bored/honed.

The cylinders must be checked for excessive taper and at a minumum honed per the ring manufacturer's specifications.

All bearings must be clearance checked with Plastigage. All clearances must meet the specifications in the service manual.

Ring end gap must be within spec. Pistons must be installed with a ring compressor or you will likely break some rings.

During reassembly, bearing shells must be properly placed. Bearings get oiled. Torque each main cap in a stepped sequence and then spin the crank by hand. Even in large engines, the crank will spin very freely. If there is any resistance, something is wrong.

Same deal for installing the rods on the crank. Torque each one and spin the crank by hand. Each piston will add a little resistance but the crank will still spin very freely. If there is any real resistance, something is wrong.

Both rod and main bearing bolts must have perfectly clean, undamaged threads and shoulders and be lightly oiled.

Then squirt some oil around each piston and spin the crank by hand a few dozen times to make sure that no rings are broken and that they and the cylinders are very well oiled.