Hate it when they do that.Vacuum advance diaphram on the Mallory distributor has a hole in it.
Been messing with me for weeks now. Took it to a friend and he started messing around check this check that pull this oh this is your problem I asked what the hose he says no the diaphram after he blew into it again. FK me! So The part is no longer made and there are zero options.
That's Holley for buying out all the cool manufacturers and then shit canning their parts to create your own.
So it's officially new distributor time along with spark plugs, new grommet for PCV valve. Fukityfukfuk