Old Curtis Air Compressor

Anonymous-0 · Aug 27, 2014

I've been looking for an air compressor for my shop and ran across an old Curtis Pneumatic Machinery Air Compressor, has a 60 gallon horizontal tank. The pump was marked 3 x 1-7/8 x 3. Doing some reasearch I was able to determine that meant it was is 2 stage compressor. After calling Curtis in St Louis the only thing they could tell me was it was built between 1940 and 1945. No specs on the CFM etc, but it will pump up to 185 psi which is where the cut out is set, takes a while though, maybe 20 minutes from zero psi. The electric drive motor was definitely replaced at one time as it's not original, it may be running on the slow side. 220V. Anyone have any experience with these...runs great and sounds good, very quiet for a compressor. Trying to keep my budget down and a new 2 stage compressor is quite expensive.

Steve@Advance · Aug 27, 2014

Curtis made good compressors from my experience. Being that old it's probably overkill to the max, in other words, a keeper!

Since it does run and build pressure and sound good I would change the oil and let it run a few days, see what it does.

The slow pumping could be bad or carboned valves. They come out the top if it's like the newer ones. Might pull them out and take a look, look for carbon build up blocking the air passages, broke springs, broke discs, eroded seat surfaces.

Parts should be available but pricey. The seats can be lapped or machined. Don't try to substitute springs or discs, they'll likely fail, can damage the pistons if pieces get in the cylinder.

If it proves to be a good compressor, synthetic oil will help prevent the carbon build up. You'll want 30w recip compressor oil.

Once you know the valves are right, put an amprobe on the motor. With it up to pressure, the motor should be running near full load amps. If it's under, you can go with a larger motor pulley, get the RPM up a little, but keep it around 500 to 600 RPM.

Steve@Advance · Aug 27, 2014

PS, forgot to say, if the gauge is right, 185 PSI is set too high.

Unless you need that kind of pressure 120 will be safer and easier on the compressor, tank, and everything else.

Anonymous-0 · Aug 27, 2014

Thanks Steve, sounds like you know your compressors. I do have a picture of the head and added my email, send me a message and I can send the picture to see if the valves come out the top. My one concern was when I called the company the man said parts were discontinued...but I wonder if they have parts from newer Curtis pumps that would fit. Like you said, being an older compressor I would say it was over designed and if was maintained well it should be a good unit, just would like to see some more CFM's.

Anonymous-0 · Aug 27, 2014

Looks like my email won't take...I'll have to figure out how to load up the picture. Thanks

Nate88 · Aug 27, 2014

Lets see if this works, trying to upload a photo.

David G · Aug 27, 2014

Curtis are good compressors.

Jerry F · Aug 28, 2014

I am no compressor expert but I love my old Curtis I picked up at a garage sale. was sitting on a plate that had an old electric 7.5 motor cobbled up to it and no tank. I took a gamble on it and bought it. I emailed Curtis the numbers I found on it and they sent back the cfm specs (19.xx@175 and rpm and HP requirements. I sized out the correct pulleys to get in the rpm range (the one on the motor was wrong) and sourced a big salvaged air tank off a rail car. And now I have a Great compressor and all the air I could ever need, with very little cash outlay.
I don't remember for sure anymore as this was 15 years ago but I think it was about the same era as yours and Curtis was still able to get the specs for me but it did seem like it took a long time for a response from them

Nate88 · Aug 29, 2014

Thanks Jerry, do you happen to know the piston size on your compressor? Mine shows that it was a model 88 on the info plate (and a serial number) and as I stated in the original post, it also listed the size of the compressor pistons. It sounds like after hearing from you and Steve@advance that it likely would be a good compressor.

Jerry F · Aug 29, 2014

My comp is mounted up against a wall with the tag facing wall. I cant get my head in there so I stuck the camera in and got a fuzzy picture of the tag. Looks like 4 something by 2 something, maybe you can make it out

XRogerX · Aug 31, 2014

That's about a 2hp compressor, based on the bore and stroke. Should give about 6-8cfm. Long pump up means worn valves, oversized tank, rpm too low, plugged filters etc. If there is an interstage pressure relief valve, pull it out, screw in a 60psi gauge and see what the interstage pressure reads. If it reads near full discharge pressure, your HP valves are shot. If it reads very low or zero, your LP valves are shot. Either way, you will not be getting the air you should be out of that compressor.

Old Curtis Air Compressor

Anonymous-0

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Steve@Advance

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Steve@Advance

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Anonymous-0

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Anonymous-0

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Nate88

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David G

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Jerry F

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Nate88

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Jerry F

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XRogerX

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