47 V8 ignition mystery

[Terry,OH]

Did you check for a vacuum leak on the vacuum line at the distributor and on the end at the intake manifold, where there is a special bolt connecting the vacuum line to the intake, the special bolt can break, or be loose or the banjo type fitting can be leaking on either side. The rubber tube to the vacuum wipers may be cracked, best to block the vacuum port at the point where the wiper tube connects to check. If your connecting to the wiper port on the special bolt with your vacuum gauge then the wiper rubber tube is not the problem.

Check for a leak where the distributor mounts to the timing cover. There should be a special rubber O-ring at the rear of the distributor that seals the vacuum to the distributor vacuum brake.