my 74 3/4 ton is idling pretty rough and stalling ... no backfiring tho . it has a 318 with edelbrock 4bbl carb and edelbrock intake out of a 95 grand Cherokee that the guy I bought if from a month ago installed in it . I have been messing with timing as well as the carb and vacuum . the timing is as good as I can get it by ear since I have no clue what it should be set to . I put the vacuum hoses back to the way the past owner had them which is the the brake booster going to the big plug on the back of the carb , the vacuum advance line from the dizzy going to the little plug on the front of carb that doest have any vacuum at idle. the other little plug on the front of the carb is capped and the big plug on the front of the carb is capped as well. the mixture screws are within a 1/2 turn from factory specs on the carb ( 1-3/4 turn out is factory specs for my edelbrock carb )
I don't have a tachometer but it sounds like the idle is at around a 1000rpm . if I went much lower it will stall without feathering the throttle... so what mostly happens is it will run fine till it warms up a little then it jumps around and sounds pretty rough and will die unless you turn the idle up or feather throttle. if you put it in drive or reverse it will stall every time you take your foot of the throttle unless the idle is turned up . then it will stall every time you step on it a little and take your foot off the thottle fast ... it has a lot of hesitation but never stalls from giving it a lot of throttle quickly just from backing off the throttle quickly and dies if you let it idle for to long without giving it throttle. the past owner says it has new timing chain and I think he was being pretty honest but you never know these days . any help or ideas would be great .
thanks-Seth

 

You may want to recheck that intake if it's off a 95 then it's a magnum intake, and your 74 is an LA engine unless you did a magnum swap. The intake bolt holes are different from the two. Unless the intake was drilled for the LA heads. The LA bolts go at an angle, and the magnum are vertical. Sounds like it's got a vacuum leak. I hooked my brake booster directly into the intake and plugged the hole in the back of the carb. I have a vacuum advance/mechanical dizzy, but I don't have the vacuum advance hooked up. The timing should be set at 10* with the vacuum advanced unhooked, and plugged at the carb. The af screws can be screwed in all the way (one at a time) and listen for the highest rpm, if you had a tach you could use that. Same with the other screw. You'll have to reset your idle after you adjust one or you'll get a false reading. But you need to get it to idle first. I'd start by checking for a vacuum leak. If nothing is obvious I'd pull plugs and look for oil, if the intake isn't sealed on the underside, it'll suck engine oil into the cylinders.