Originally Posted by 85e150six4mtod

Bad shifting after a carb change could be:

--vacuum modulator not connected. There is a tube from the carb or carb base to the trans and it must be connected for proper shifting.

--kickdown linkage not adjusted properly, causing the trans to hold the lower gear just as it would at WOT.

If it spun the tires from a standstill with a 4bbl, it should do the same with the 2bbl. The difference is the 2bbl will go soft on power compared to the 4bb at the higher rpms.