In Reply to: weak spark at plugs posted by Greg on June 12, 2020 at 08:58:58:
12V conversion with modern ign wires and .045" plug gap running an internal resistor coil?
Your swapping all kinds of electrical and I wonder about your carb adjustment? vacuum leaks?
If you desire a hotter spark at the plugs, try backing the coil wire off the internal coil connection just about 1/8 inch. That will effectively increase the coil output due to the additional air gap that needs to be overcome. Back it out too far and the engine will die.
Chances are the choke operation is making it nice and rich to run cold.
It is also a cold engine and has not had time to expand such as the intake manifold to the head. Gasket leak causing a vacuum leak?
Gasket leak causing a vacuum leak is my guess.
Then again the batteries are dead in my crystal ball so that is just an official SWAG. Others with far and vast more knowledge and great experience will be along shortly.