Quincy Model A4 (Roc 7) Valve Change
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  1. #1
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    Default Quincy Model A4 (Roc 7) Valve Change

    Hello Everyone!
    I just recently purchased a compressor with a Quincy model A4(Roc-7) pump on it. It's a HEAVY cast iron, rock-solid, very well built pump. I've decided to rebuild it (new rings, gaskets, valves, and springs) and bring it back to like-new condition. I've ordered a re-build kit.

    The problem I'm having is with the valve change. I was able to get the intake valve out without too much trouble but the discharge valve is a different story. The only way to get it out is to take off the "discharge valve bumper" (part #2515 in the diagram) which looks like a large 1-1/4" bolt on the top of the head (I've included some pictures and a pump diagram in the post). It will NOT budge. I've tried to heat it up with propane and use a breaker bar and cheater bar - it didn't budge. I tried an impact gun - didn't budge. It looks as though it might have been either brazed or welded closed. If I use an oxy-acytelene torch and heat it up red hot then go at it with an impact gun will that work or will I just rip it off and ruin it?

    Has anyone ever rebuilt one of these pumps or changed the valves or know much about them? I've looked closely at the diagram but can't really tell if the bolt (bumper) is threaded. Does anyone know if the factory brazed or welded them closed? And does anyone know about what year this pump was made? It's a single cylinder Model A4 "Legend" with a Record of Change 7 and serial #257777. I've sent Quincy an email but they haven't gotten back with me yet.

    Any help will be appreciated!

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  2. #2
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    I would let it soak in your favorite penetrating oil for a few days, then try brute force again. Failing at that some judiciously applied heat (hot wrench) may allow it to break loose.

    Dan

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    Talking

    [QUOTE=CBC317;2800424]Hello Everyone!
    I just recently purchased a compressor with a Quincy model A4(Roc-7) pump on it. It's a HEAVY cast iron, rock-solid, very well built pump. I've decided to rebuild it (new rings, gaskets, valves, and springs) and bring it back to like-new condition. I've ordered a re-build kit.


    The valve plug is threaded into the head - it isn't welded or brazed from the factor - but heat from hot discharge air and time have rust welded it in place, I'd bet.

    Since you already have the head off of the compressor, the big deal is going to be holding it solidly while applying brute force. You could probably clamp the head in a vise using wood blocking to protect head surfaces.

    I would use at least a 1/2" impact gun and lots of penetrating oil. Try not to use adapters, extensions, etc. on the end of the impact gun, as they lessen the rattle effect that the gun puts out. Also, "blips" of the impact gun are better.

    If the impact gun and penetrating oil don't do it, then heating it up may help. You may also try freezing it, which won't burn out the penetrating oil. Anything to cause a little bit of movement between the parts. A canned air duster turned upside down will spray liquid refrigerant, which would be good to chill just the valve plug.

    I've also heard that folks have had good luck freeing stuck parts in an electrolysis bath. Look up electrolysis rust removal for more info.

    Hope this helps.

    Kevin

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    The bumper (plug) looks to be made of steel, while the head is cast iron. Quincy used a copper gasket to seal the valve plugs or caps on their various compressors.
    They did not weld or braze the valve bumper into the head. My guess is someone in the past, confronted with a persistent leak at the valve bumper, decided to "fix" it. Rather than obtain or make a new copper gasket, or anneal the old one for re-use, they probably got something like the old black Permatex and big wrench (maybe helped along with a cheater pipe). After the heat of the compressor baked the Permatex, it set up.

    I've worked on a few Quincy compressors as well as some I-R's and Worthington compressors over the course of my career. I've had to deal with frozen parts in the cylinder heads. What always worked was to put plenty of heat into the head, particularly around the threads of something like a valve cage or stuck top cap or plug. We used a brazing tip on an oxyacetylene torch. Keep the heat a bit back from the threads so the mass of iron surrounding the threads gets warmed up and expands. With the head well secured to a bench top or something solid, I'd then try an air impact wrench on the head of the bumper.

    Another trick that sometimes works is to heat the male part (bumper) to a dull red heat. Let it expand and cool, and when the head is also fairly cool, spritz on some penetrating oil like "Kroil". The heating/cooling cycle may do one of several things:
    -burn out the Permatex (or pipe dope or whatever the last guy put on the threads)
    -the expansion and contration of the male threads within the tapping in the head may break any bind
    -as the head/bumper cool, keeping the accessable areas of the thread soaked in penetrating oil may cause it to be drawn into the threads.

    Heat + Impact often works when a lot more torque applied to a threaded assembly won't break things loose. Compressors, depending on location and ambient conditions, can produce a lot of condensation in the heads when they shut down between cyclings. I've seen cylinder head assemblies on compressors that looked like they had been under water, heavily rusted, from being run in a plant where there was high humidity and cool ambient temperatures. We had to get the valve caps and cages out of the heads (this was a high pressure Ingersoll Rand compressor in a small hydroelectric plant) using a lot of heat and a lot of "persuasion".

    The head on the compressor you have is cast iron. I doubt that anyone would braze or weld that valve bumper into the head as the heat would take the spring temper out of the valve springs (Quincy uses disc valves) and the hardness out of the valve discs. I am unfamiliar with the model Quincy compressor you have. Unfortunately, Quincy went through a number of changes of ownership, and with each change, some of their product line was changed or deleted due to overlap with other products the new owners had in other divisions. How willing and how extensive Quincy's records on the older compressors are is anyone's guess. Quincy has been around a long time and always made a very good recip compressor. I used to spec them whenever possible for anything from shop air to use in the hydroelectric plants for charging governor air and brake air, and bought a few for railroad locomotive airbrake service.

    Over the years, Quincy was pretty consistent in their designs and quality. Then, and I am guessing this had to be a good 15 + years ago, Quincy changed the design of the main castings on the cylinders and heads of their compressors. Same overall dimensions and interchangeability of parts, but the castings took on a coarser design and finish. Instead of numerous finely cast cooling fins, the cylinders and heads suddenly had fewer coarsely cast cooling fins. We also started seeing errors in machine work on new compressors we were getting. I called Quincy after they could not send the right parts properly machined, and after even a compressor pulley/flywheel had better than 0.100" face runout. The giving me the runaround. I finally got the head of the division on the phone and told him in plain English as to the fact I'd bought a lot of Quincy compressors over the years, and the quality had taken a dive, and it was a sorry state of affairs when a compressor left the plant with a flywheel with 0.100" runout, wobbling like a drunk, and the oil pressure relief bypassed all oil flow from the lube oil pump due to poor machining at the factory. The head of the division said he'd make sure we got good compressors, and they changed out the junk we had gotten. He said the problem was due to the usual corporate mergers and takeovers. We got good compressors- finally.

    Quincy usually was good about supporting their older compressors with parts, mainly because not too much changed from one revision to the next. Your compressor does look old, unless I miss my guess. I'd try the heat on the head, using a smaller brazing tip and concentrating the heat in a circle around the tapped threads. If you do not have valve springs and discs to rebuild the head with, I'd try to avoid getting the head too hot, and try to use localized heating.

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    Default Great! Thanks for the ideas.

    Thanks for all of the ideas!
    I put the head on a long 1 x 6, drilled holes and bolted it down. I tried heating it up with mapp gas and oxygen, then put on a breaker bar with a cheater bar on it, again. It snapped the breaker bar in the socket.
    I think I'll let it soak in penetrating oil then freeze it for a few days. I think I'll drop by a garage and ask them to try a 1/2" impact on it, I only have a 3/8" impact. I'll let you all know how it goes.

    Is there any chance that it would come out clockwise?

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    You can't bolt it to wood. Wood dampens. Bolt it or clamp it to something rigid. Get a real impact. 3/8"- No way!

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    Quote Originally Posted by CBC317 View Post
    Hello Everyone!
    I just recently purchased a compressor with a Quincy model A4(Roc-7) pump on it. It's a HEAVY cast iron, rock-solid, very well built pump. I've decided to rebuild it (new rings, gaskets, valves, and springs) and bring it back to like-new condition. I've ordered a re-build kit.

    The problem I'm having is with the valve change. I was able to get the intake valve out without too much trouble but the discharge valve is a different story. The only way to get it out is to take off the "discharge valve bumper" (part #2515 in the diagram) which looks like a large 1-1/4" bolt on the top of the head (I've included some pictures and a pump diagram in the post). It will NOT budge. I've tried to heat it up with propane and use a breaker bar and cheater bar - it didn't budge. I tried an impact gun - didn't budge. It looks as though it might have been either brazed or welded closed. If I use an oxy-acytelene torch and heat it up red hot then go at it with an impact gun will that work or will I just rip it off and ruin it?

    Has anyone ever rebuilt one of these pumps or changed the valves or know much about them? I've looked closely at the diagram but can't really tell if the bolt (bumper) is threaded. Does anyone know if the factory brazed or welded them closed? And does anyone know about what year this pump was made? It's a single cylinder Model A4 "Legend" with a Record of Change 7 and serial #257777. I've sent Quincy an email but they haven't gotten back with me yet.

    Any help will be appreciated!
    That part will come loose with enough torque applied to it, altho 'enough' might have to be 'a lot'. Your real challenge is that of finding a way to secure that head to an 'immovable object' to resist that torque without cracking or breaking the casting.

    A 'cheap, quick, and dirty' way to have enough torque is to use a common 36" pipe wrench, preferably the 'Ridgid' pattern, and a 8-12 (whatever is readily available) foot long piece of pipe which will fit over the wrench handle. Enlist a very strong helper to pull with great vigour on the end of the pipe, and be ready to take a quick heat with the torch, just under that hex. This will put wrench scars in the part, to be sure, which will be noticeable after filing down the raised burrs.

    Another option might be to have the part well secured to a mobile 'immovable object', and take it to a local heavy equipment repair firm, who will have 3/4" and 1" drive air impact wrenches.

    Personally, I would first consider trying to get a replacement part, if it is available, or a drawing from which to make one, then setting the head up in a light vertical mill, and drilling/milling the part away, out to minor diameter of the thread. Then its an easy task of picking out the thread, which should come out looking like a coil spring. I've used this technique on well and truly stuck parts, on the theory that this creates the least risk of damaging the relatively unobtanium casting.

    cheers

    Carla

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    Quote Originally Posted by Joe Michaels View Post
    .Quincy has been around a long time and always made a very good recip compressor. .
    Over the years, Quincy was pretty consistent in their designs and quality. Then, and I am guessing this had to be a good 15 + years ago, Quincy changed the design of the main castings on the cylinders and heads of their compressors. Same overall dimensions and interchangeability of parts, but the castings took on a coarser design and finish. Instead of numerous finely cast cooling fins, the cylinders and heads suddenly had fewer coarsely cast cooling fins. We also started seeing errors in machine work on new compressors we were getting. I called Quincy after they could not send the right parts properly machined, and after even a compressor pulley/flywheel had better than 0.100" face runout. The giving me the runaround. I finally got the head of the division on the phone and told him in plain English as to the fact I'd bought a lot of Quincy compressors over the years, and the quality had taken a dive, and it was a sorry state of affairs when a compressor left the plant with a flywheel with 0.100" runout, wobbling like a drunk, and the oil pressure relief bypassed all oil flow from the lube oil pump due to poor machining at the factory.
    That is sad and appalling to hear. I'm a big fan of Quincy compressors, and I'm
    glad all the ones I have are way older than 15 years!
    Although my smallest 210 does have some run out on the flywheel.
    I've always attributed it to it the fact that it came off the pile at the local scrap yard, and I thought it may have gotten bent up. It's not out .100 thankfully.


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