Quincy Compressor 350 Pump - how many hours are too many?

dschad · Aug 9, 2019

Hi all,
I'm considering buying a mid-90's Quincy with a 350 pump. This is pressure lubed.

The reported hours are 12000. I know I wouldn't want to run for 12000 hours, but can someone provide thoughts on how much wear this would represent? Over 20+ years this doesn't seem like much per year, but is there a guide for how many hours these go without rebuild?

Rumor has that these run forever - any thoughts on how close to 12,000 hours is to forever?

The original motor was spec'd as a 10HP, but it currently has 5hps on it. Don't know when they were changed.

Any thoughts are appreciated.

Thanks,
Don

Karl_T · Aug 9, 2019

I have a <VERY> old Quincy 350. For the rotating bottom end, forever is a good number.

After only about forty years, I did have to go though the head mostly to clean years of carbon build up, replaced springs, reed valves, and gaskets while I was there (about a $125 kit). Runs like new. I may have to work on it again in forty years.
QUINCY 350, HEAD OVERHAUL KIT, R.O.C 11 to 12, AIR COMPRESSOR, | eBay

I got manuals if you need them.

Garwood · Aug 9, 2019

Service interval on a Quincy 350 is 12,000 years. You're fine.

I have a 350 that is rev 18 that runs all the time. It has a sixteenth play in the crank and spits a little oil out the crank hole (no seals back when it was made). Runs nice and quiet and builds air a little slower than it should, but it sure as hell won't die.

A 350 is happy from 5HP to 10HP at 5HP it should be almost dead silent. Just a real mellow thump, thump, thump at 400 RPM.

Only QR25 Quincy's I have ever seen broken were a pair of 390's I bought from a National Guard base. They filled them with gear oil and just let them sit there spinning for days.

When I first went into business I had a 310 from the 30's that was originally attached to a large marine engine. It had plaques on it from the boatbuiulder and looked a fair bit different from the later QR25's. It ran like a champ though.

guest · Aug 9, 2019

I replaced a QR25 with a screw for the noise, that Quincy was bulletproof.

dschad · Aug 9, 2019

I really like the idea of the low RPMS, 400 seems really slow.

That said, I was surprised to see that at 5hp it puts out 3cfm less than a 325. Good to have the option to up-motor in the future.

Thanks everybody.

Karl - thanks for the manual offer. I might take you up on this.

Bill D · Aug 10, 2019

There is a minimum rpm for a air pump. so that oil is splashed around enough. 400 seems too low to me. Ones with a oil pump it is probably a lower safe rpm. I would guess 600-900 rpm is a safe lower rpm.
Bil lD.

Garwood · Aug 11, 2019

Bill D said:
There is a minimum rpm for a air pump. so that oil is splashed around enough. 400 seems too low to me. Ones with a oil pump it is probably a lower safe rpm. I would guess 600-900 rpm is a safe lower rpm.
Bil lD.

Quincy QR25 minimum RPM is 400. They are pressure lubed and can't build air pressure until they have oil pressure.

As small compressors (under 50 HP) go, there's nothing better than the QR25's.

A 350 pump alone weighs 480 pounds.

I have an LP piston from a 390 I use for a door stop in my shop. It's 7.5" diameter.

dkmc · Aug 11, 2019

To the OP.......you should pull off the side cover when you get it, and drain, and clean out the bottom of the crankcase.
If it's had the proper compressor oil in it, any dirt or sludge will have settled to the bottom. If you're really curious (probably not THAT curious) you could spring for an upper end gasket set, and pull the head off, check the valves and cylinders. Many of the old units still have cross-hatch showing in the bores. That compressor should last you your lifetime with a little maintenance. Less and less people these days understand the difference between the QR25 series, and the 'pro-sumer' junk Quincy is now peddling in the box stores.

Garwood · Aug 11, 2019

Just a little additional... If you pull the head off an older QR25 go further and replace the rings.

The rings from 20+++ years ago were real thick. They use a lot of oil. If you buy ring packs from Quincy for a recent rev same model compressor they will fit your pistons, but the actual surface that seals is much thinner so the compressor will have far less blowby.

dkmc · Aug 11, 2019

Garwood said:
Just a little additional... If you pull the head off an older QR25 go further and replace the rings.

The rings from 20+++ years ago were real thick. They use a lot of oil. If you buy ring packs from Quincy for a recent rev same model compressor they will fit your pistons, but the actual surface that seals is much thinner so the compressor will have far less blowby.

Did not know this, excellent tip!

Garwood, are the rebuild kits on EBAY viable or are they inferior quality?
Any idea?

Karl_T · Aug 12, 2019

dkmc said:
Did not know this, excellent tip!

Garwood, are the rebuild kits on EBAY viable or are they inferior quality?
Any idea?

I ended up getting a hold of that eBay vendor directly to get one for my rev unit. They were great to deal with, parts were perfect.

Wish I had known that piston ring thing but my unit showed no issues in the rotating bottom part. How many other companies like Quincy that improved an already indestructible product?

dkmc · Aug 12, 2019

Karl_T said:
I ended up getting a hold of that eBay vendor directly to get one for my rev unit. They were great to deal with, parts were perfect.

Wish I had known that piston ring thing but my unit showed no issues in the rotating bottom part. How many other companies like Quincy that improved an already indestructible product?

Thanks for that info.
But now I'm wondering, wouldn't thinner rings cause more cylinder wear? Or the thinner rings will wear out faster. I've never noticed much if any oil blow-by with my units.

PS, I'm just lazily blurting out questions without thinking about thin ring advantage possibilities.

Garwood · Aug 12, 2019

I just buy parts from the local dealer. Prices always seemed pretty fair.

Never pulled one apart after putting new rings in so can't say if it wears more.

Karl_T · Aug 13, 2019

Say Garwood,

Are there any tricks to removing burned on carbon? I was hours and hours chipping it all out. I don't know how the compressor even ran but I bet they all look like that inside.

dkmc · Aug 13, 2019

Abrasive blasting with Alu. Oxide in a pressure pot blaster would remove the carbon efficiently.

Garwood · Aug 13, 2019

Hot tank with lye works pretty good.

dschad · Aug 16, 2019

Planning on picking the monstrosity tomorrow.

Does anyone have a chart for pulley size versus CFM at various pressures? Or one other pressure, I'm wondering what sort of CFM I might get at 125PSI with a 5HP.

Thanks,
Don

dkmc · Aug 16, 2019

5HP = 400 RPM 15.6 CFM @ 175PSI
Pretty stout.....480 lbs for just the pump.
You'd need to know the compressor pulley pitch diameter to calculate the motor pulley needed @ whatever motor RPM you have.

https://mi-air.com/wp-content/uploads/2017/02/QR25-009-0515.pdf

dschad · Aug 17, 2019

So I am now the proud owner of an FF350:

from 1998. It has two 5HP motors and 18k - 20k hours/pump. So that is the good news. The (possibly) bad news is that the control panel is configured and rated at 460V

, which is not the voltage which I was hoping to use. I need to run it at 230V, so I'm wondering about converting this panel:

to operate on 230V. I'm hoping that all the components are suitable for up to at least 7.5HP/230V and maybe the limits are due to the fuses? Is the panel/duplex manager going to be a lost cause?

I'm thinking each component should have a voltage/current rating and then the wires need to be sufficient gauge, so I can visually check that out, but is there more?

Any thoughts on where to start looking at this would be really appreciated.

Thanks,
Don

PS - Karl_T -

Karl_T said:
I got manuals if you need them.

I can find the Qunicy manuals online, like the parts manual: http://www.engineservicesupply.com/contentonly.aspx?file=pdf/350L PARTS BOOK.pdf

and the user manual: http://airenergy.com/files/products/quincy-qr-manual.pdf

Are there others? I'd be really interested in the one entitled "Converting your Duplex Controls to 230V".

Thanks.

Karl_T · Aug 17, 2019

Can you look at the motor itself and see if its rated for 220? Many are dual voltage

Quincy Compressor 350 Pump - how many hours are too many?

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