I have a Carter, not a Holley?

what he told you is VERY right. dont let that parts man get away. just for reff here is my AFB jetting inst set. Title: AFB and edelbrock carb / the short verson.

setting an AFB carb takes time. make only small changes. and give it time, dont make changes in an hour or two. drive it in different ways over a day or two. on AFBs or AVSs change only the jet OR rod at one time. and start with the jets. a .003" change can be felt if you try. dont forget .003" on a .060" jet is less change than .003" on a.100" jet. Then start changing the rod. A little is a LOT. i do have a computer program to cal any combo of changes. but it is lost in some main frame of my sons. Sometimes you can set the float level to 5/16”. the stock setting is 7/32. if at 5/16” at idle the fuel runs out of the main discharge nozzle reset to the stock setting. NOTE: do NOT change jets AND rods at the same time. Do not put the jets in tight, just snug is fine