Long story short, I had a working D15B2 with MPFI swap and it worked fine. Swapped it for a D16Y8/Z6 combo. It worked great until a bearing spun. I had another D15B2 and put it in, but it wont start. I have no spark. The engine is heavily used and I don't know its history. It turns over very slowly. The battery is less than a year old and has a full charge. Tried jumping with another battery and still, slow cranking. It is harder to turn at the crank pulley with a breaker bar than the other motor were. I have given in that this motor is crap and probably has internal damage, rust, sludge adding too much friction for it to turn over smooth. I swapped starters to make sure that was not the issue. Plug wires ohm out OK, plugs are new and gapped correctly. I still don't understand why I have no spark.

Followed the FSM for checking the dizzy, wiring, and ECU. Everything seemed OK, but I swapped out a known good dizzy just to be sure. Still no spark.

I am wondering if there is a minimum RPM before you will generate spark. Anyone have thoughts on that?