So i installed a 20r carb on my truck with a lc adapter plate, it now runs really good with a LOT more power but i cant figure out why when i come to a stop it takes a fiew seconds for the idle to come down. It does this more noticably when the a/c is off. Any one have a clue as to why. On a side note this swap was mainly due to the secondary would not open in the 20r carb no matter what i did. Any insight would be very much apprecated

 

Several questions come to mind -
The subject line reads "22r carb on a 20r" the first line says "i installed a 20r carb on my truck" - please clarify which. And specify the year(s) of the parts and truck.
Were all of the connections (vacuum, etc) exactly the same?

Pictures may help

The new carb may be better only because the old carb was in bad shape.

 

There is an air buffer on the carb that keeps it from slamming closed, it may need some adjustment.

 

Well im kinda a retard, truck is a 1980 with a 20r in it, i put a 22r carb on it. I played with the idle a little more lastnight and lowerd the float to 9.mm and it seems to be better, not ware i think it aught to be but noticably better.

 

No the old carb, was remanufactured, has a 2007 sricker on it, it ran great just the secondary wouldnt open so it was justa tiny 1 bbl. I have no idea what year the 22r carb is i bought from aircleaner to intake manafold for 20 bucks so it was kinda a no brainer. I do have all the vacume lines hooked up they may not be right but they are plugged in.