springer3

My car had crossed wires on one of the distributors - probably from the first dealer tune up. I thought the car ran great. The butt dyno reported a 3 HP increase (barely noticeable) after I got all the wires all going to the correct cylinders.

Moral: even the pros screw up, so don't assume it is right just because it runs OK. Disable the distributors one at a time. You will get some pretty rough running if two or more of the cylinders stop getting spark at the correct time.