Onboard air from stock AC compressor, pressure switch
What pressure switch are you guys using? Is there an over the counter option or am I going to have to bust out the msc catalog?
CF Veteran
Joined: Aug 2008
Posts: 6,588
Likes: 495
From: Chico, CA
Year: 1986
Model: Cherokee
Engine: 4.3L with headers and full 3" exhaust system
I use a 150# switch with a 200# relief valve. You are going to use one aren't you? That compressor will pump 400 psi easily. You can get them from various places. I got one from Amazon. Kilby Enterprises has all that stuff if you cannot find it anyplace else. Did you plumb in a check valve? You will need one of those too. Best not to try to start the compressor under load or have your pressure bleed back out through the compressor valves when it cycles off
CF Veteran
Joined: Aug 2008
Posts: 6,588
Likes: 495
From: Chico, CA
Year: 1986
Model: Cherokee
Engine: 4.3L with headers and full 3" exhaust system
You can lube them internally if you vent the crank case. I have run the one in the vid for about ten years now internally lubed. If you don't vent the crank case, the internal pressure will push the oil out past the piston rings and run it dry

The old Chrysler V twin compressors were the best for making these. They actually had an oil pump in the crankcase that pressurized the crank and rod bearings. But they were big and needed lots of room. lol
I use a 150# switch with a 200# relief valve. You are going to use one aren't you? That compressor will pump 400 psi easily. You can get them from various places. I got one from Amazon. Kilby Enterprises has all that stuff if you cannot find it anyplace else. Did you plumb in a check valve? You will need one of those too. Best not to try to start the compressor under load or have your pressure bleed back out through the compressor valves when it cycles off
https://www.youtube.com/watch?v=q39yoOjlU4c
https://www.youtube.com/watch?v=q39yoOjlU4c
Since the compressor is lubed with oil circulating through the system, I've considered putting a "T" in my PCV line and pulling air in through that.
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yeah, that's the idea, i figure the air leaves an oil residue in the air filter intake tube, hopefully that's enough to keep everything ok. if not, i'm in michigan, quite a few cherokee's headed to the junkyard every day.
Might work! I would be curious how it affects the engine vacuum. You may want to put a check valve there too so that when it is off it can't bleed back though as a vacuum leak. I wonder if it will end up being a vacuum pump? If you do this please let me know how it turns out and affects the engine vacuum? 

It shouldn't affect the engine vacuum at all as it's sucking air from the crank case, there is more than 1 vent in the valve cover and vacuum comes from the intake.
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