Lizardking, welcome to smokstak! That is a great find. There is nothing better than a Quincy QR-25 series compressor and a Wisconsin engine. As Greg mentioned, the Quincy 325 is a real workhorse of a compressor. They are one of the only compressors that can run 25,000+ hours between rebuilds. The Wisconsin AENL is equally as stout and can be rebuilt over and over again. Your setup is not from 1947. The Quincy 325-7 came out on January 15th of 1958 and had an updated connecting rod for both the high and low pressure pistons. Your Quincy 325-7 compressor was superseded by revision 8 in March of 1962. You are lucky that your compressor was not built before 1958 as it would have had ring oilers instead of a dedicated rotary vane oil pump which was Quincy's standard until Atlas Crapco bought and destroyed Quincy starting in 2004. You should be running Mobil Rarus 427 ISO 100 SAE 30 oil in your compressor. You should check the oil regularly for water buildup as your compressor has VD dual control on it. When free-wheeling the compressor will discharge the inlet air into the crankcase of the compressor. You can download a Quincy service manual and parts list online for free on their website. Quincy has always used Solberg air filters and they can be had on ebay cheaper than your Quincy dealer. Unloader diaphragms are really easy to replace. The diaphragms are on the top of the unloader towers under the six flat head screws on the intake side of your compressor. You can certainly rebuild the valves, and I would recommend you doing so. Quincy changed the spring loaded pins, valve discs and bumper springs many times over the years. Your compressor will have spiral taper springs which are more noisy and yield less performance than the current replacement. Do not buy aftermarket parts, buy genuine Quincy, you will be glad that you did. Keep in mind that the model 325 is a 3-5 horsepower compressor. It is at most 16cfm. You will be okay running a #4 (1/4") nozzle in your blast cabinet, but nothing larger. Do NOT overspeed your compressor to try and make it pump faster. Most blasting takes place at 90psi. Your compressor has a maximum operating speed of 900rpm. Before you run the engine and compressor anymore, you should pull the engine off of the platform it is mounted on, and pull the oil pan. These engines have an oil pump in them that needs to be cleaned from time to time. The check balls in the oil pump are known to stick preventing the oil pump from working properly. Most of the time the oil is never drained hot or changed periodically, so you will likely find 1/4" of sludge in the oil pan. Clean everything out nice, test the oil pump, and refill the crankcase with Rotella T-1 SAE 30 or similar high grade detergent oil. Do not use synthetic oil in these engine. I would not run a multiweight oil in your engine either. Parts are readily available for your engine. The AEN has been in production for over 60 years. It was one of the most rugged 9 horsepower air cooled engines that money could buy. I am not certain that the Prestolite ignition timer/distributor was actually available when your unit was built. It likely had a Fairbanks Morse magneto on it at one point in time. I cannot tell from your pictures if your unit has an auto idle setup or not. Some of the Wisconsin compressors I have seen had either a big centrifugal clutch on them, or were direct drive with a small air cylinder mounted on the carburetor controlled by the compressors unloader, to auto-idle the engine. When setup correctly they worked really nice.
Chris
