Posted for <13brv3@mchsi.com>:

Oops, I meant to include this question in the last message.    Since I ordered AN16 fittings on the radiator, I will need have these on the
water pump housing, and thermostat housing as well.  What's the best way to
do this?  I noticed that Earls sells a fitting that goes from 1" NPT to
AN16, and I wonder if the housings can be tapped to accept the 1" NPT.  It
looks like the ID of the housing is from 1-3/16" to 1-1/4", but when I try
to find drill size info for a 1" NPT, I find different sizes.
Unfortunately, in a brief look today, I was unable to lay my hands on a
fitting, or tap locally, and I hate to order both, only to find out that
they won't work out.  If the fitting will even thread in loosely, I could
use some Tracy (I mean JB) Weld to help secure it.  In the back of my mind,
I'm thinking that I read where someone did just what I'm proposing.
  
The other option of course is welding to the housings, but as I've
mentioned, my torch abilities are limited to melting stuff :-)      Rusty
Turbo 13B powered RV-3 (experimental aircraft)...Be Afraid :-)
1993 RX-7 R1... Not stock, carry bail money :-)
  

[The recommended drill size for a 1"NPT tap is listed as 1-5/32... not exactly your run-of-the-mill drill bit.  A cheap taper shank bit in that size is over $30, the good ones start out in multiples of that price.  One inch pipe taps are also prety expensive, although you might be able to find one on Ebay at a reasonable cost.  You may find it cheaper to give the pump housing to a friend who works in a machine shop and pay him to bore and tap it for you... just a thought.

      <marv>        ]