The Stovebolt Site Forums The Shop Area General Truck Talk Wiper arms 1950 1/2 T

I have been down this path and screwed around with old wiper motors and vacuum pumps until I was blue in the face. The little bakelite parts in the motor distort over the years and it they're too distorted you can't file them flat. A good vacuum pump should give you whatever the manifold vacuum is plus whatever the pump can add. At idle it should be like 15 inches or so. There is a spec for what it should be when disconnected from the manifold, 8-10 in Hg @ 25mph according to the Chevrolet truck service manual for 1948-51. So climbing a hill at 30 mph and like 2-4 in. manifold vacuum the wipers should still work.

The problem with the repop pumps is that not only are they expensive but they begin to suck oil after a few thousand miles. I went through two of them before I gave up. I bought the electric wiper kit and never looked back. Absent the electric wiper you can fit a vacuum tank somewhere with a check valve between it and the manifold. I saved one off an old Studebaker but traded it off at some point. I was able to get an NOS vacuum/fuel pump for the Studebaker and drove it without problem for many years in rainy Seattle. So when in good conditions the vacuum system works pretty well.