Mysterious Engine Failure - Ideas, please

[John H]

FWIW, our chummy (fitted with a DJ distributor) requires a points gap of about 20 thou to get the required 50 to 60 degrees of dwell (measured with a proper automotive dwell meter). The engine runs very badly with the recommended gap of 12 thou. The cam lobes are not obviously worn out, but I've found that using a dwell meter is the only way to set the points up properly, at least on this particular distributor.