I’ll start of by saying I’m the type of person who likes OEM replacement parts and will spend the extra money on them. Most of the time I feel the quality is just better and always a correct match. Here are some comparisons of quality aftermarket parts vs OEM Quincy QR parts and my take on them. This is only comparing gasket sets, valve discs, main rod bearings, a valve bolt and rod cap nuts as these are the parts I have on hand to compare side by side. Ill start with the main bearings, they look very similar, same box, same finish, design, and fit tolerance In the cap and rod. Only thing I see is the machined surface where the two halves meet is ground cleaner on the OEM. I’m assuming they might be made by the same company? The valve discs are identical, if you swapped them in your hand you would not know which one was which ,and as far as springs I don’t think there is much difference. The gaskets are a different story, in addition to having the Quincy name and made in USA, the OEM gaskets feel and look better quality, they have a nice supple finish that almost looks like they can be reused to some extent. The OEM inspection cover gasket for example is a correct rubber cork and the aftermarket feels like a cheap fiber gasket. Also the OEM has real steel shims, compared the cheap aluminum shims. Quincys also includes the 005”rear bearing cover paper shims, the aftermarket ones are some kind of plastic. Not sure which ones do a better job of sealing as they are used against the machined block surface and shaft seal cover, I prefer the paper and believe they can only be soured OEM.
As far as the aftermarket piston rings go, I feel they are very nice quality and probably similar if not the same as OEM but have none to compare. Theres other parts that are usually needed on a full rebuild not found in the kits. For example broke / deteriorated valves components. I had a badly rusted bolt that holds the valves together, the aftermarket was about an 1/8” short, i wound up getting OEM and was right on. Same with the rod cap nuts with the plastic retainer. I usually try and replace these for good measure. I did order aftermarket nuts but wound up ordering OEM and the difference is evident, the aftermarket look like hardware store nylock nuts compared to the OEM.
So as far as the aftermarket kits go I don’t think you can go to wrong with the rings, bearings and valves as I feel they are comparable. The gaskets and such i was not happy with and also went OEM, although they may have worked fine. When it comes to miscellaneous parts and hardware not found in kits I would probably lean towards OEM. Overall OEM was not much more money and If I was to order again I would just get the OEM and be done with it. Hope this helps future reader. Below are some comparisons with the OEM on the right, you be the judge and what ever you decide if installed correctly your pump will run fine.
