> Tom Kendall wrote:

While stripping down the 20b, I found an air pump with both inlet

and

outlet

fittings (it was clearly used to pump air *into* the engine... I

suspect

for

some kind of emissions thing).  While heavy for aircraft use, it

sure

seemed

like it would handle instrument duty, and probably a darned sight

cheaper

and longer lived than an aircraft vacuum pump.  Anybody have

experience

with

these?

That is the air pump and is used for, among other things, putting air
into the catalytic converter to provide oxygen/air in it so that the
emissions are lowered (high temps needed). There is a pipe that goes all
the way to the cat on all rx7s I have worked on as well as 20Bs. It has
a clutch and disconnects at certain rpms. Neat standby vac source,
clutch controlled no less. Also GM had an electric motor driven air
pump-clutch driven as well, used on some Vettes as I recall. Lots of
options for vac.
[Marc Wiese]

For vacuum, I elected to use the brake booster vacuum pump for a '92-95
Cadillac.  Folks on the rah ng recommended this as several of them have
been using them for years.

AI Nut

 
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