Air compressor information

Categorized as Workshop Notebook 10 Comments on Air compressor information
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There were many pages of air compressor information that used to linked from the right hand column, and that column was getting mighty long. In order to make finding information on a little easier I’ve taken all those pages and listed them below by subject titles, trying to categorize them for you to find the air compressor information you are looking for more convenient.

If you are looking to resolve a problem on your compressor, the page on this site linked here is where to scan the list of problems and solutions.

This page offers a broad range of information about compressors in general. To see what it’s about, please scroll down and have a look and click the link that provides more info about what you are looking for.

Compressor buying / sizing / function

Compressor identification

Compressor fittings

Compressor plumbing / lines / fittings

Compressor pumps

Compressor repair / additional components

Valves on compressors

About Compressor tanks

Compressor pressure switches

Air tool pages

More general compressor information pages found on this site include the following:

By Ashley Pearce

As a passionate manufacturing and mechanical engineer, I've had my fair share of run ins with air compressors and compressed air systems. With over a decade of experience in the industry, I have both a fresh perspective and time-served hands and mind to help you with your compressor problems (along with our able community!)

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Mickey Mooney
Mickey Mooney
June 19, 2023 10:25 pm

I have a Snap On Big Red 20 gallon horizontal portable air compressor with a 220V 3HP motor. I bought it in 1986. I need a replacement air tank. I’ve been looking but can’t find one. Can anyone help me out?

Chris Reuter
Chris Reuter
September 22, 2022 11:35 am

I have a 3Z323 speedaire, Im looking for a 6 rib belt for it, 50 ” x 9/16, I haven’t had much luck finding one so,

Kevin T
Kevin T
October 5, 2021 5:52 pm

I recently inherited a 1972 model air compressor. The tank is labeled Standard Refrigeration Company. It looks like it was reworked at some point along the way but I may be wrong there. The copper line from the pump outlet running through the belt seems to be a give-away to some tinkering at some point. Also, the regulator valve (and maybe the entire regulator–who know) appears to have come from a gas cylinder based on the markings on the gauge which says to order gas below about 27 psi. Also the frame is bolted to a piece of plywood which is attached to the tank. Maybe this is a Frankenstein.

It seems to run OK. It just put-put-puts along and builds pressure. I have no idea if it is doing so at full efficiency. I ran it up to 100 psi and closed the main valve and it lost about 7 psi over 4 hours. Not sure how much of that was temperature related.

It has no pressure switch which I would like to add. I can’t find any port on the top of the piston to which a line to an unloader valve would have been installed. If it has made this far without an unloader valve, do I need to worry about one? If I need one, can I just add a check valve at the tank and install a “T” in the line coming from the pump outlet and run a line to an unloader valve. There are some components at the outlet of the pump which may be a check valve there.

There is a nipple at the base of the pump (noted in some pictures as “What is this?”) which looks like it was made for plastic or rubber tubing. I would be interested to know what this is for.

Any input on this compressor would be appreciated. It has some sentimental value to me and I could use a small compressor in my shop so I’d like to get it a little more functional and put it to use.


July 21, 2021 3:08 pm

I have a Central Pneumatic 21 gal compressor model # 63635.
were can i find a Piston & a Connecting rod?
my connecting rod broke and it bent my piston in the process.

Fix My Compressor Moderator
Fix My Compressor Moderator
Reply to  Alan
July 21, 2021 8:11 pm

Alan, as I’m sure you have found out, though this compressor appears to be still available new from Harbor Freight, they do not supply the parts in question. That information is available on this page (if you follow this link), and if you click the “view available parts” link on that page, it will show the parts available from HF.

I’ll post this, but I have no confidence that you’ll find an after-market supplier since the compressor is still available new, and HF doesn’t carry these parts.

Suggestions? Go on the free sales sites and browse for a working used version, or, buy a new one, and use the old one for parts for when the new one, too, fails.

mike venth
mike venth
January 24, 2021 5:09 pm

Model # 67847 Help looking for crankshaft and connecting rod.

Fix My Compressor Moderator
Fix My Compressor Moderator
Reply to  mike venth
January 24, 2021 5:18 pm

Mike… nope. None, nowhere that I can find. So sorry.

Maybe a kind owner has a used on for sale, and maybe they’ll post here. Otherwise, if the tanks good, you may need to buy a different pump and motor entirely.

Anyone help Mike with 67847 crankshaft and connecting rod for the pump?

mike venth
mike venth
Reply to  Fix My Compressor Moderator
January 24, 2021 5:40 pm

Been looking all day,,, Thanks for your help….

Fix My Compressor Moderator
Fix My Compressor Moderator
Reply to  mike venth
January 24, 2021 8:10 pm

You are welcome. Wish we’d been a bit more help. Let us know if you get anywhere with this, if you would. Might help someone else.

mike venth
mike venth
Reply to  Fix My Compressor Moderator
January 25, 2021 8:56 am

will do