PorKen

People convert them to air compressors (1, 2), so why not a vacuum pump? It's an awsome pump, loves oil, already fits on the engine, and can be engaged at will...

There would probably have to a vacuum limiter (eg. 14" mercury popoff valve), because the pump would surely be able to pull some serious vacuum.

Now, looking at the rebuilt compressor prices, it might be a bad idea, but I have a compressor I'm not using anyway.
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Further, with some valving, perhaps it could be used as an air compressor at low rpm to power an exhaust amplifier (thread), then switching to a vacuum pump to pump down the crankcase for high rpm horsepower.

SharkSkin

I think our compressors are designed to blow oil through the system along with the freon. The Jeep retrofit you pointed to utilizes a York compressor with an oil reservoir. Anyway, it might work out fine... what the heck, bring it on!

PorKen

Used as a compressor, I'd like to have an inline drip oiler, but as a vacuum pump, it should get enough oil from the engine vapors?

If you look at first website above, he's using a Frigidaire log, and manually oils it.

928FIXER

The old A-6 Frididair compressor has a oil sump in it.Thats why they lasted forever on the old GM cars.The nippondenso used on the 928 would not last long without a continous flow of oil thru it.Bad idea

SharkSkin

I'm not sure about that... the only way to find out would be to try it. With a vacuum on the crankcase, wouldn't you expect less oil to get blown out? It might be worthwhile to add an oiler until you can be sure you don't need it. They are fairly cheap IIRC. ~$50 for one with a 3/4" - 1" inlet/outlet.

I decided to double-check myself as it's been quite a while since I was in the market for one of these... Here's one that I Googled up(click pic for page):

SharkSkin

Also you might consider check valves on your breather hoses... that way, you can pull a vacuum, but when the pump is not running your breathers will operate more or less normally...