"Erika" <yamaha237@hotmail.com> writes in article <1144417503.776668.88010@u72g2000cwu.googlegroups.com> dated 7 Apr 2006 06:45:03 -0700:

The purpose of an "air pump" on an engine is to add air to the exhaust
before it goes through the catalytic converter.  The catalytic converter
needs something from the air (O2 maybe?) to work right.

Look for a fitting anywhere between the exhaust manifold and the catalytic
converter.

-- spud_demon -at- thundermaker.net
The above may not (yet) represent the opinions of my employer.

Well, think about what the air pump does.  It takes air in from the
outside (maybe from behind the air filter, maybe not) and it pumps it
into the exhaust.  

Then, think about what it's for.  Some catalytic converter designs
need considerable amounts of oxygen in the incoming exhaust in order
for them to work properly.

Next, think about when it arrived.  The air pump came in with early
catalytic converter designs in the seventies.  On some vehicles, you
will see an air pump arrive one year, then disappear a few years later
because the catalytic converter design changed.

SO... the question is... did your original engine have an air pump?  
If not, it probably wasn't required with the converter that you have
used... and if you have had to change the converter to go with the
larger engine, you may have to make some exhaust system modifications
to connect the air pump up.

This sounds like a very fun project.  I never got to do anything like
this in high school.  My high school, though, worked very hard to steer
smart kids out of the auto shop classes and used them as a dumping ground
for students on the lower track.  Now, twenty years later, it's hard to
hire good mechanics around here.  Sheesh.

Personally, I'd try just leaving it disconnected if the exhaust system
has no place for it.  Get an emissions test done on it... if it passes,
just remove it.
--scott