Rough running/Carb flooding?

My 74 CJ runs and drives great, but when I've been romping on it for a while (hour or so) offroading, It runs a little rough and has a hard start when it stalls. After it sits for a little while, It fires right back up in again nice and smooth. When its idleing rough, it will run pretty good if I keep the RPM's up (around 1000 maybe?) but sputters when I just let it idle in 4 low, creeping real slow (500 or 600RPM) over rock or something. Now this only happens when I am on and off the gas pedal, going real slow, idling real low over rock or something thats real jerky. It would never do this driving a little faster and smoother. I notice the carb starts to get just a tiny, tiny bit wet from gas around the intake manifold, so I'm pretty sure its just flooding out from running rich. I would think I probably should start with leaning out the mixture screw a tiny bit, but does it sound to you guys like it might be something else? Something in the carb not working or choke not operating?

PS When I set the mixture screw, I put a vaccum on the intake manifold and set it at the highest vaccum.

 

Did you ever put a fuel pressure regulator in it?

Pete

 

Nope I fine tuned the float a couple times and it ended up running perfect. For the last month or so, I've been taking this rough running condition as just something you deal with when owning an old stock cj. I means its reliable and always gets me home. But now I'm wondering how easy it is to fix. I am starting to think maybe the float has to be brought up just a tiny bit more? And with all the rock and throttle jerking, the float is just getting thrown around. Like I said, once it smooths out on a trail or I hit the road again, everythings back to normal. I assume every carb is gonna be a little different so the float adjustment isn't exactly the same for all, but maybe something you have to play with? But also, I might just have to lean out the idle screw.

 

When you say 'mixture' do you mean the idle mixture? Usually that's set to 'best lean idle' where you go leaner-leaner-leaner until the engine starts to stumble, then back it out maybe 1/4 turn. Then adjust the idle speed. Best vacuum may be way too rich.

What do the plugs look like after it's idled for a while? What do the plugs look like after it's driven across town and back?

The high-speed mixture is not adjustable (typically) without disassembling the carb and replacing the main jets, or adjusting the float level.

A dirty EGR valve will cause a rough idle too.