I've been using an HEI w/ a Mallory module & Accel coil, for years ... in my 70' Elky. Recently, this vehicle quit running, caused by loss of 12v power to distributor. I was a little surprised when I discovered the source of the problem .... And, this is what I found. ----- I was using the original harness wire (white,cloth fabric covered) for 12v. In the harness, behind the master cylinder, this wire had burnt through, but not it's covering. This was not near a connection or splice, which could have caused high resistence. Ran a new larger wire from fuse box to distributor .... and problem solved. I first thought the problem to be at the wiring harness bulkhead connection. I don't know if this is a common "problem", but hopefully this can help someone else.