I may have solved the puzzle of my running problems. More than two years ago, a great person from the Full Moon Bus Club lent me a distributor to help diagnose a problem. The van ran well with the loaner so I ordered a rebuilt from the guy in Pennsylvania. Needless to say, I did not have the same results with the rebuilt distributor and figured it must be vacuum leaks or throttle position switch or air flow meter or fuel pressure and on and on.

Symptoms were that van would start and idle but as soon as I cracked the throttle it would hesitate and bog and miss. It would run OK at wide open throttle.

Turns out that the re-builder used two different sized springs on the centrifugal advance counter weights. The effect was that there was no resistance at all from one spring. As soon as the RPM's started up, the distributor went full advance.

I had a ridiculous and completely unsatisfactory response from the company I bought the distributor from. If you look carefully at the top spring in the picture, you can see where the bail of the spring on the right side does not touch the shaft. Also, compared to the bottom spring, the top spring smaller gauge wire. I bent the bail to shorten it and problems went away. Sort of.

When I reassembled the distributor, which had no shims and might not have had the key-way pin that locks the trigger wheel into place. Whatever I used as a substitute key-way pin fell out or got chewed up. I redid that with a pin cut from a nail that fit fairly snugly in the slot and so far so good.