I recently bought a "PAR" air compressor, model "15", manufactured by the Lynch Manufacturing Company of Defiance, Ohio in 1945. It has 2
90 degree opposing pairs of low pressure and high pressure cylinders (4 cylinders total) in a cast iron block. It is splash lubricated, and the reed valves sound fine through the cylinder heads. The motor is a 2 HP 120 VAC Baldor, and is clearly not original. The original motor mounting plate is very large relative to the Baldor, and the shives are 2-belt, which to me means 7.5 to 10 HP. Also, the Model "15" nomenclature sounds like it might mean 15 CFM, which this compressor is clearly not doing at present. 7 or 8 CFM tops, right now.The Baldor is 1750 RPM, and the shive looks like it could be orignal. I was thinking of putting a 3550 RPM 7.5 HP motor on the compressor to get the flow up to where I think it probably was originally intended to be. I'd like to run a large blasting cabinet with this unit, and at present it's not up to it.
My questions are:
1) Should I re-shive and stay at 1750 on the motor, or go to 3550 RPM on the motor?2) In terms of maximum crankshaft rpm, is there a rule of thumb for old cast iron compressors heads?
Thanks very much for the help! Dave