In Reply to: Fan Belt Length For a Small Genny posted by Paladin (Bob In PA) on April 10, 2013 at 23:21:08:
Hi Bob-
Don Barkley sent me this information recently...
Tim.......according to the parts books..........the “A”and “B” gennys used part number 52-8620-C belts and the “C” gennys used 9n8620-A belts.Mine has a 52-8620-D belt. don
Now, I also recently purchased two NOS belts from Scot Deppen with the FORD logo and part number 9N8620-A1 and 9N-8620-A2. Both measure around 44-45 inches in circumference but Scott said they will fit an early 'A' or early 'B' generator.
I just got my 'B' generator back from the shop but it's not going on my early 9N -I'm holding out for an 'A' genny and believe I will find one soon. I have a new solid state VR to go with it. I have not mounted the 'B' genny and tried a belt. The 'B' genny is sold and spoken for.
Here's a bit of technical info from the world of machining. "V" Belt Grooves are machined and measured 'Over The Roll' or 'Over The Ball' to determine functionality. There is a dimension given on the blueprint that shows what the diameter is as measured over two precision roll pins or balls 180 degrees apart as they lie in the 'V' groove. This dimension is determined to be the 'effective pulley diameter' and not the actual diameter of the OD of the pulley itself. Being an old machinist, CNC Programmer, and later Process Engineer, I've machined and processed parts with numerous 'V' grooves using everything from precision made cemented carbide form tools to single point machining larger grooves to multiple poly grooves using specially made indexable/throwaway carbide inserts which I designed myself.
All that being said, you should be able to find a belt that'll work using the 9N8620A part number. The pulley sizes varied from the early 3" to later 3-11/16" so I would think you could adjust the slack simply by varying your position. I may be way off base here but seems logical to me.
Tim
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