1600 dp engine "catches" while turning

[jeromeaircooled]

I am working on my the engine for my 74 standard beetle. 1600 dual port. This is an engine that ran before parked six years ago. I pulled the engine and noticed that there is a bit of a catch at one point when turning it with a wrench . I pulled the heads and cyclinders on the 1 and 2 side and it then turned smooth. Reinstalled the cylinders and heads and it turned over smooth. Built the engine all the way back up and went to put the belt on and the catch came back! I can turn it all the way around and it stops at the same place. I can then rotate the engine counterclockwise and it will turn over smooth, then rotate it back around clockwise and it will turn through maybe four or five times, then catch again. Got any tips.

This car was supposed to be a cheap and easy driver. The engine is kind of turning into a nightmare though. Yikes! Plus we are now down to one car and unfortunately we need two. Remember that steep drive I I have to take in my bus regularly? Well, it's even scarier and a hell of a lot more work on my bicycle.

[Amskeptic]

there is a bit of a catch at one point when turning it with a wrench .
I pulled the heads on the 1 and 2 side and it then turned smooth. Reinstalled the cylinders and heads and it turned over smooth.
Built the engine all the way back up and went to put the belt on and the catch came back! I can turn it all the way around and it stops at the same place. I can then rotate the engine counterclockwise and it will turn over smooth, then rotate it back around clockwise and it will turn through maybe four or five times, then catch again. Got any tips?

Pull the plugs and rotate by hand. Smooth? Locks up?
You can localize the hang-up by feeling how the engine stops.
Do you get a clank? Let someone else run it against the clank point
again and again and see if you can localize the sound somewhat.
What cylinder is at intake open? Which cylinder is at exhaust open? Which cylinder is at TDC overlap and which cylinder is at compression/power? Engines can get stopped by a chunk of carbon jamming between the piston and the combustion chamber. They can also get stopped by bad valve timing (crank/cam gear marks off), this one is up to you to track down, there are too many variables. Get rid of them one at a time. Turn the engine with the belt off in 4th gear gently. Free? Stops? Crap in the bell housing? Keep searching. . . .
Colin