I have a 307 engine installed in one of my cars. It ran fine for a while with a new HEI after market distributor. Now I have no spark. First I checked the spark at several plug wires. Then checked power to the distributor which was good. Had the control module tested, it's good. Tested primary and secondary readings at the coil - all good. I even bent the spring on the rotor so it would be sure to contact the carbon tip on the cap. Retested spark at the plugs - nothing. Running out of ideas. Have new distributor, wires and plugs. HELP!!!
Pull the rotor and look for burn-through. check the spring between the button and coil. Check the wires on the pickup coil for internal breakage (pull test)
If its a HEI with the coil in cap take the cover off the coil have someone crank it over and watch for spark jumping over to one of the screws that hold the coil in. Could be that the coil has a leak in it.
I used a trick to pulse the (inside the distributor, not external) HEI module - simulating a pickup coil signal: remove pickup coil leads from where they connect to module's 2 pins/blades. With 12v to coil and other primary connections to coil intact, quickly touch the module's exposed pins where you disconnected pickup coil from. Do it several times quickly while checking for spark at the coil button. This checks for bad pickup coil by using your body's internal voltage to simulate pickup coil signal. Also inspect pickup coil leads. If the distributor has vacuum advance, years of rotating the pickup coil can fatigue the leads. They look ok until you bend them back to inspect. Posted using the Full Custom H.A.M.B. App!
check the pick up coil for continuity , the wires are real small and thin and brittle and sometimes the vac advance movement will break them or the manufactuer make them too short and they snap off the coil