Moved carb, now it idles very low

[ankarback]

I've moved my Quadrajet carb from my blazer to my new suburban and when I started it up the idle is very low. Only difference between the trucks is that the suburban doesn't have A/C so it doesn't have the little plastic vaccum-tank for that. I plugged that vaccumport but can this really affect the idlespeed or did I mess something up?
Offcourse the easiest fix is just to turn up the idlescrew but I like to know what causes this before I do that. Anyone have an idea what's wrong?

 

[pauly383]

Both trucks may have the same size engine . But I betcha cams and heads may be different enough . You always must fine tune it to the engine its on . There is no such thing as bolting it on and going .

 

[MTMike]

Also check the timing - if it's too retarded it will idle low... too advanced will idle high.

Mike