Identifying Quincy Compressor

[Ten4321]

I have a Quincy QR-25 Compressor that came with my truck when I bought it. The problem is the compressor has no markings on it to indicate the model number. Based on it's dimensions I believe that it is either a 370 or 350 model. Is there anyway that I can tell what model it is? The compressor was driven by a three belt pulley connected to a 23hp Kohler Engine. According to the QR-25 brochure the 390 would be the only model that could handle over 20hp. The dimensions of the compressor, however, would indicate that it's a smaller unit. The Kohler Engine is cooked so I am looking for a replacement. I just want to get an appropriate engine for the compressor. Based on the price of horizontal shaft motors I would prefer to buy one under 15hp.

[averagef250]

I have/have had 310's 325's, 350's, 370's and 390's from records of change from 1949 through the late 90's.

A 325 weighs about 300 pounds, 350 weighs about 400 pounds, 370 weighs about 450 and 390 is in the 550-600 range for just the pump.

Originally there would have been a riveted plate about 1" X 2" on one of the crankcase covers that would have the model and ROC numbers. If that's missing post some pictures and measure the cylinder height. You can always pull a side cover and measure the cylinders. Some share bore sizes like 350/370, but the 370 has an inch taller cylinder.

Also, 23 gas HP is equal to about 10 electric HP. Not to mention the HP these pumps require is directly related to the pressure they're set to unload at. You can run a 390 on 5 HP at 400 RPM and 175 PSI or probably spin it 700 or so if you kept the pressure around 100 PSI. My 350 is set up to run 550 with 7.5 HP at 150 PSI. I could spin it faster, but I like the gentle "thup-thup-thup" it makes and can listen to it all day everyday- And I do.

[QuincyCompressor1]

Are you able to locate the serial number of the compressor? If you can or even if you can't, our Quincy Compressor service department will be happy to assist you with your questions. You contact them by phone at (217) 277-0200 or via email at recipservice@quincycompressor.com. Thank you

[Ten4321]

I emailed Quincy but they have not responded. Not that I blame them I did acquire this compressor second hand. Someone had mentioned that a 23hp gas motor would be equal to a 10hp electric motor. I understand that gas motors only put out their total hp at a specific rpm and they lose power over time, howerver, I would think that under normal operating conditions a 23hp gas motor would put out more than 10hp. If I were to get a 10hp electirc motor what kind of setup am I going to need to operate it.

[averagef250]

What model compressor is it? What are your air requirements for CFM and pressure? The displacement/rev numbers for Quincy compressors are published all over the internet. Set it up to deliver the CFM you need with the largest pulley size the motor will spin for the pump's displacement at it's given HP.

QR25's are designed to run 24/7. They don't necessarily have to, but they do not like to sit idle or run for 3 minutes and kick off. My current 350 takes about 45 minutes of running to reach operating temp. If they run cold the oil will not burn off the water that gets past the rings and you'll be doing frequent 2 gallon oil changes.

In order to set it up with an electric motor you will need to do the math for the appropriate pulley size, order the right belts, align the motor properly, plumb and wire a pressure switch and contactor. If your pump has the selectable unloader on it you should set it up for continuous operation so you can run it balls out the way it was intended to operate. They run a lot more efficiently when they run non-stop and just unload the intake valves somewhat like a screw compressor.

[Ten4321]

What model compressor is it?

This was the original question of my post. There are absolutely no markings on the compressor aside from casting numbers on different pieces. I've measured it and compared that information to the Qr-25 brochure. There are three models that it could be based on dimension. I am also not sure if I should include the oil filter in the length measurement.

Here are some pictures of the compressor.

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[averagef250]

Pull a side cover and measure the bores. Post the cylinder height.