Quincy 325 Electric to Gas Conversion

[InjectorService]

I have 2 Quincy 325 compressors, and I would like to convert one to be used in a gas-powered truck-mounted application. I have a few questions regarding this process.

1. I'm assuming I will need to convert this pump to unloading. How is that done?
2. Do I need a pressure controlled throttle for the gas motor?
3. Do I need to use a reserve tank, or can I run my equipment directly off the pump?

Thank you in advance for your help!

 

[MacMcMacmac]

You need a 10-12hp gas motor, a tank, and a throttle control/unloader valve.

Like this:





You need a bullwhip throttle control cable to screw it into the small 1/8" npt outlet on the left. Tee off this outlet and send the same air signal to the unloader towers on the cylinder head. Once the system is up to pressure, the pilot pops, unloads the discharge line above the check valve through the screen outlet, throttles down the motor, and unloads the cylinders. Once pressure drops, the air signal disappears, the motor throttles up, the unloaders retract and the compressor goes back online. You can unload the system and throttle down at any time by pulling the little aluminum pin on the top. You need a tank or this setup will be short cycling like crazy. Keep the hydraulic unloader valve on the side of the pump hooked up to the tank to keep the low oil pressure protection active.

 

[whateg01]

I wish I still had the 325 gas pump. I would have swapped you. I was always going to convert it to electric but never got around to it so I got rid of it a couple years ago.

 

[InjectorService]

You need a 10-12hp gas motor, a tank, and a throttle control/unloader valve.

Like this:





You need a bullwhip throttle control cable to screw it into the small 1/8" npt outlet on the left. Tee off this outlet and send the same air signal to the unloader towers on the cylinder head. Once the system is up to pressure, the pilot pops, unloads the discharge line above the check valve through the screen outlet, throttles down the motor, and unloads the cylinders. Once pressure drops, the air signal disappears, the motor throttles up, the unloaders retract and the compressor goes back online. You can unload the system and throttle down at any time by pulling the little aluminum pin on the top. You need a tank or this setup will be short cycling like crazy. Keep the hydraulic unloader valve on the side of the pump hooked up to the tank to keep the low oil pressure protection active.

Thanks very much for the reply. It looks to me like the blue 325 I have is already setup for this, with the exception of the throttle control.

On the tank question, I will be planning on running this compressor to power an air diaphragm pump that demands about 25cfm at 40psi. It will be running for a couple hours at a time. Knowing this, do you still think it will be short cycling too much?

 

[InjectorService]

I wish I still had the 325 gas pump. I would have swapped you. I was always going to convert it to electric but never got around to it so I got rid of it a couple years ago.

Dang that would have been perfect. Do you have any pictures of your setup so I can get an idea for line routing etc?

 

[MacMcMacmac]

If that's all you re running it will be going pretty much flat out the whole time, but when you hit cutout pressure a hose will drain down pretty quickly. Air storage is always a good thing Air straight from the pump is also going to be very hot at such a high duty cycle.

The green one also has everything you need for this. It might be easier to package without the filter hanging off the end of the pump. I'd be worried about something puncturing that. Make sure you pull the aluminum pin at startup, since there won't be any air to actuate the unloaders. This will let the pump freewheel without pumping air while everything gets up to speed and temperature.

 

[InjectorService]

If that's all you re running it will be going pretty much flat out the whole time, but when you hit cutout pressure a hose will drain down pretty quickly. Air storage is always a good thing Air straight from the pump is also going to be very hot at such a high duty cycle.

The green one also has everything you need for this. It might be easier to package without the filter hanging off the end of the pump. I'd be worried about something puncturing that. Make sure you pull the aluminum pin at startup, since there won't be any air to actuate the unloaders. This will let the pump freewheel without pumping air while everything gets up to speed and temperature.

Thank you very much for the help, my hope was to use the green one, and leave the blue one in the shop if I could.

I will try my best to post some pictures of the compressor as I build it.

 

[InjectorService]

Ok, so I'm going to start on this tonight. I have a Honda GX620 motor, a plate to mount everything on (I don't have a tank yet, but want to get everything setup and tested first, I might just mount this plate right to the tank. once I have one), and obviously a few QR325 compressor heads.

One question I have is, how do I get tension on the belts of this gas driven air compressor? The electric compressors are easy with the little motor sliding plates.

Any suggestions?

 

[Zewnten]

Mount the gas engine the same as the electric motor, slide to tension. I wanted to try my hand at an electric clutch when pressure was reached.

 

[whateg01]

Mount the gas engine the same as the electric motor, slide to tension. I wanted to try my hand at an electric clutch when pressure was reached.

I'm not sure if or how that would interact with the unloaders

 

[MacMcMacmac]

I've used UniStrut as an ad hoc motor mount in the past. That was for electric though, you might need to keep an eye on that for a gas engine.

The unloaders will work fine with a clutch. I tested a factory Champion with one about 20 years ago. Electric clutch, head unloaders and a centrifugal blowdown valve. The pump stopped completely while the engine idled. Top notch.

 

[InjectorService]

Lots of good info here, thanks guys. Pulled the pump off the donner motor. I hate lifting these pumps, that's a lot of weight swinging around up there.



Any recommendations on how to prep the pump for paint? Something other than sandblasting maybe. I'm thinking some paint stripper, a quick wash down, and some rattle can. This isn't going to be a full resto, just a good working machine that's not green.

 

[whateg01]

That's not a lot of weight. 600# of drill press, xy table, and vise is a lot of weight. Not the heaviest thing I've lifted with an engine hoist, but still don't want it landing on my toe