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Wipers no work - they did (poorly) 6 months ago, before I started the rebuild. Checking vacuum at the metal line from the pump, I see it fluctuating, -7 to +2, maybe 3 times a second. Well, 7 pounds vacuum isn't gonna run the wipers...

Correct me if I'm wrong (no manual at hand, engine rebuilder still has it), but isn't the fuel pump vacuum supplemental to crankcase vacuum? If that is the case, I think what I am seeing is FP vacuum alone... that would explain the gauge readings I'm seeing.

How does crankcase or manifold vacuum get added, and what would cause it to be absent?

Engine is purring, plenty of power. It, and everything attached, was completely rebuilt.

The vacuum side of the pump has one line going to the wipers and one to the intake manifold below the carb. If you check manifold vacuum at the intake and then at the wiper hose connection you should find the wiper hose connection should give at least a 3" higher reading but 5" higher would be preferred..