For the kind of IFR you can fly in that kind of airplane, and
considering how docile it is partial panle, I would suggest you stick
with a venturi to drive your vacuum gyros with a large venturi, and put
in an electric T&B. That is a perfectly viable setup (I once trained
an IFR student in a Pacer set up that way) and will not require field
approvals.

A 337 is a record of major alteration (the installation of a Venturi
and some gyros is generally considered minor, though your FSDO may
differ, and thus requires only a logbook entry) and has to be backed up
with either the type cert, an STC, or a field approval. Unless your
mechanic has an in at the FSDO, you won't get a field approval.

You can look up all the STC's available for your airplane at:
http://www.faa.gov/aircraft/ (click on the STC link a few lines down
the page). There may be one for your airplane/engine (look it up both
ways).

In the long run, it will probably be cheaper to sell your airplane and
buy one that is already IFR capable.

Michael

gt wrote:
I would like to make my 1960 Cessna 172A IFR. Currently, I have only
venturi vacuum. My A & P stated that as there is no STC for a vacuum
pump intall, I need a form 337 field approval...I think it is form 337,
I could be wrong on that. Does anyone have information relating to
STC's and field approvals for vacuum pump installations on a
Continental 300-C?