Drill out the jet hole in the brass nipple. For starters, I am using a #60
drill bit for the jet. I may increase that later on depending upon the heat
and flame stability I get.
Step 3: The
next step involves drilling out 2 holes in the reducer bell to accept the
1/8" pipe nipple mounted perpendicular to the flow through the bell.
In this case I started with a 13/32" drill but soon found I needed to
use a letter "Z" drill bit. The extra .007" was the
difference between the brass nipple fitting or not. I first measured back
from the large end of the bell enough to make sure the nipple just cleared
the thick part of the bell end and then center punched a starter
indentation using a spring-loaded punch.