Charlie Kuss wrote:

Thanks Charles, looks like that pump is a cheap solution to the vacuum problem

in

auto conversions. You can get these pumps for free. people that sell  engines,

just

toss them in the junk pile. I noticed there are few different sizes with

different

size pulleys.
BTW what else is needed to regulate the vacuum - regulator, accumulator tank?

Please

let us know.

Buly,
 I would suggest that frugality not extend so far as a used A.I.R. pump. These
items are NOT expensive. They have a life expectancy of 80,000 to 100,000 miles on
autos. Most of the ones you'll find in a junkyard will be near the end of their
life cycle. As was mentioned earlier, when they fail, they seize. (These pumps are
non serviceable, meaning there are no rebuild parts available for them.) This
destroys the fan belt. If you use only one belt, you will lose your water pump and
alternator in the bargain. Losing these items while IFR would ruin your whole day!
:-(
 I would suggest running a separate belt AND an A.I.R. clutch. The second belt
would give you extra security as regards the function of your water pump. If either
the alternator or A.I.R. pump where to fail, the other belt would still drive the
water pump. That said, I have seen a belt fail and take the belts near it off of
their respective pulleys while they flailed about before breaking entirely in to
two parts. It is for that reason that an A.I.R. clutch is a good idea. Even if the
failing belt doesn't destroy the other belt, it may well ruin your cowl if you
don't dis-engage it with the clutch. That possibility alone is worth having the
clutch.
 You will need a regulator to reduce the vacuum to the 4-6 inches that vacuum
instruments prefer. A vacuum reservoir tank will serve 2 purposes. It will damp out
variations in vacuum and cover momentary drops in vacuum during throttle position
changes.
Charlie

 
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