1939 Ford flathead belt size
 

Hi again everyone!

Quick question:
What fan belt size would be correct for my 1939 Ford flathead? The belt would cover both water pumps, the generator, and obviously the crankshaft. I tried measuring the old one and I got around 53 inches, but it’s a bit worn and not the most accurate. I saw some 52 inch ones online and was wondering would those work?? :confused: Let me know what you think is best.

Thanks!!

Re: 1939 Ford flathead belt size
 

Most common is a B51, which is 54" long. (B series belts measure 3" longer than their part number)

Re: 1939 Ford flathead belt size
 

Caddy , that’s why we come to the FordBarn.
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Re: 1939 Ford flathead belt size
 

Apparently there is no one answer to this question. Depends on model and valve chamber cover composition (alum or cast iron). Here's a chart from the EFV8CA 38-39 Ford Book:

Re: 1939 Ford flathead belt size
 

Re: 1939 Ford flathead belt size
 

Is there an echo in this room? ;)

Re: 1939 Ford flathead belt size
 

I keep a bunch of cut belts. I set the generator or alternator down to its lowest point on the engine and then take a cut belt and wrap it around the pulleys and take a measurement of the length, maybe add just a little to it. That usually works out pretty good by the time I tighten it up. The local stores should be able to sell you a belt based on the length and if you need a little more of less you can return it and swap it out.