Motors running, idle issues

[56 Aero]

My 69 sb is getting closer to hitting the road. I bought a slightly used 600 Eldebrock model 1406 from a friend, he took it off his 67 Mustang and replaced it with a Holley. He found out his problem wasn't the Eldebrock but a motor issue. I get it on my 302 and it starts right up, the electric choke works, but the high idle seems to high around 2k rpm. I lower it just a tad, I blip the gas and it drops. So far so good. Put the truck in reverse (C4) and the idle drops and the truck starts to shudder. Ease the gas down and she rolls down the drive way. Pull out on the road and hit it, she runs pretty good, some stutter and slight stumble here and there. Pull up to a stop sign, got to hit neutral to keep it running. I ran both left and right mixture screws in and backed them out around 4 half turns. It runs but should be much better. My biggest question is about the idle when I put it in gear and why it's so rough. I paid $50 for this carb. and don't know what was done to it nor does my friend, (some guy worked on it is all he knows) Should I just get something else maybe a Motorcraft 4100? Intake is a factory aluminum from early 80's Mustang. Sorry this is so long and Thanks for any ideas or info......Rick

[fordman]

how did the engine run prior to the new carb. did you rebuild the new carb before putting on. it doesnt sound like a vacuum leak but i wouldn't rule it out.

[56 Aero]

The motor was running ok with the stock two barrel. A little more history, the motor and tranny came from a 71 that was running but a smoker. I had the C4 rebuilt and I put valve seals in the 302, added the intake and carb and put it in my 69. The smoke is gone, the stock gauge shows decent oil pressure, the motor starts quickly, shifts through the gears nice and crisp. When I hit the gas quick it stalls then revs quickly.I did not do anything to the Eldebrock, I took it out of the box and mounted it. I assumed it was ok, not to smart. I quess I'm also hoping it's just a carb problem, not something else. Plugs and wires are fresh. The points and condenser I have not changed, but the motor was not doing this before the carb swap. So what do you think?.....Rick

[Dragon]

Rebuild it. And then check the needles and jetting for your particular engine mods.

This is where a Holley beats the Carter AFB/AVS and Edelbrock copies. Easier to jet and adjust, they have less variables. Not only do you have to deal with Jets you have to sometimes get to tweak it with needles. Mostly seat of the pants stuff.

[willowbilly3]

Before you attack the carb make real sure you have no vacuum leaks.

[56 Aero]

Thanks Dragon and Willowbilly, I'll get a rebuild kit and try it again. Vac lines are all new also, but I'll check them out too. Thanks again guys......Rick