Attach the vacuum line to the carb fitting on the throttle side. If the 2100 is a 1.02 a 48 set of jets should be completely adequate, with the range being 46-48. The stumble may be due to a lag between the forward movement of the throttle and the accelerator pump. Look closely to see that there is immediate accelerator pump engagement with the slightest throttle. Adjustment is made by bending the accelerator pump rod in such a manner that it is shortened the required amount. It is a little surprising that the rod had to be moved to the top hole. Hot summer temps generally require less pump shot. Some references say to drop the rod down one hole in the summer, going back up in winter. Most people just leave it alone on number 3 year round.
If you are going to stay with the 2bbl, at a later time it would be good to look for a 1.08 or 1.14 to replace the undersized 1.02.
Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.
