[boblyon1]

I had my 351w rebuilt 2 months ago. This re-builder is extremely knowledgeable and sharp. I am running a straight Holly, no vacuum advance, with MSD 6AL ignition and an MSD distributor and coil. After about a 1000 miles of break-in, I took it in for timing and other adjustments. It had lately been popping in the 4500+rpm range, showing a few beats of dieseling on shut-off and occasionally backfiring, but not real loud. There had been a gradual decrease of power, most notably above 4000 rpm.

My re-builder was surprised that the timing was so far off. He re-set the timing and it ran well initially. Now (about 400 more miles) its doing the same thing and I suspect the timing is "slipping" again. The distributor is not loose at all, so I'm a little worried that there is some distributor gear wear. I DO NOT have a bronze distributor gear, it the standard steel one.

I searched the archives going back several years and can't find a problem associated with a 351W and distributor gearing. Any suggestions or ideas?