Questiontrying to set up carb to run on 72 gmc with 350 need to know proper float drop and level. also noticed that carb sems to have difrent size jets like a primary and secondary. witch one goes where. any help would be gratly apresheated. engine is stock as in no radical cam or anything
AnswerI can't help you much, because I don't have the truck shop manuals or the rebuilder kit instructions for your carb -that is where the info is.
The primary jet is the smaller jet, in every carb I have rebuilt.
The float drop isn't extremely important, just so it clears the sides of the bowl and lowers enough so the needle valve is pulled open. The float level setting is something that IS important, however, and I'm sorry I don't have that info.
For what it's worth, in the 1972 Chevrolet passenger car application, (carb 7042106) the settings are:
float level 19/32,
float drop is 1 7/8,
vacuum break is 0.085,
choke rod is 0.060,
choke unloader is 0.215,
top fast idle setting is 2800 RPM.
Try those and see how it runs - it should be pretty close (but that idle speed seems awful high!
I hope this is helpful.
Dick
