I am making a carburator for a model engine.
The throat of the carb is 3/16.

The bottom of the throat (below the throttle plate) needs to
be enlarged with a 1/4 inch drill with a 45 degree angle.

I figure I will drill most of the way with
a standard drill bit to enlarge the 3/16 hole to 1/4. Can
I use a spade bit with a 45 degree angle to finish it off
and establish the angle? Would it be better to grind a
twist drill into a 45 degree angle?

thanks
chuck