dist. cap & rotor, interesting info(possible poor milage culprit)

Was going through the motions this past weekend of indexing the distributor after rebuilding the engine and adding a Crane cam, Borla header etc.. I cut a window in the old cap to aid in the indexing and when I installed it I was able to see that the rotor seemed to be sitting below the pickups/posts for the individual plug wires. I figured it must just be a mismatch between the new rotor and the old cap and continued on with the indexing. When i finished up and pulled the old cap off I looked at it and it was obvious that the old rotor was never actually in contact with the posts. It was riding about 100 thou of an inch below and the spark was just jumping the gap. Installed the new cap and rotor, ran it in the driveway for its initial warmup then checked the new cap and it was obvious that the rotor was making contact about half way up the post, just as you would think it should be.

I'm sure this was a contributing factor to my pre-rebuild poor gas mileage and miss at idle. Not sure where I bought the old cap and rotor but I suspect it was NAPA, as there was a napa warehouse just around the corner from the house I was in at the time, that I used for most of those kind of parts.

Anybody that is fighting poor mileage or has bought a cap and rotor set at a NAPA or other cheap parts house may want to pop the cap off and check to make sure you can see a contact path on the posts in the cap. Easy enough to do and it might make a difference in performance etc. I'm sure I'm not the only one that had/has this problem.

Tim