[HEI451]

OK, lets stop all the speculation, and fix this issue.

Large cap HEI's use an in cap mounted coil (shown above) that MUST have their yokes (outer framework) grounded TO THE ENGINE. If they are NOT grounded, NO SPARK. That path is from the buss bar, to the three pin plug, at cap position GND, down the wire, to the wire loom mounting screw in the distributor.

The ground path is, coil yoke, buss bar ground tab (shown above), CENTER (GND) wire on the 3 wire connector between the coil plug in at the cap and body, ground wire enters the distributor, and travels to the SCREW that holds down either the wiring loom, or wiring loom and NOISE SUPPRESSOR.

I'd check the grounding by using an ohm meter, between that buss bar in the cap that fits under the coil, as in the picture, to the distributor body. Should have NO RESISTANCE FULL CONTINUITY.

Now, IF you want to do it a lot better, obtain one of the kits that move the coil OFF the cap, and use a round, oil filled coil next to the distributor. That way, the problems of module failure from coil layer shorting, and under cap excessive temperature will be eliminated.

I always get flamed for my posts, but, I wonder why all the self proclaimed ignition specialists here that always shout me down when I post real fixes, didn't outline it already. Oh, well, back to fixing what the specialists tell people to do, that doesn't work. Busy day doing that, I just to this work EVERY day.

Also, ACCEL coil gives NO advantage iof any kind over a stock GM or good aftermarket OEM (Wells, NAPA, CarQuest, O'Reilly's, Auto-Zone, etc.) replacement large coil in cap HEI coil. .