This weekend I finally got a 2-bbl installed on my dart. It's off of a 76 Dodge truck. It seems to run pretty good (a lot more snap!! - I can't believe how much difference it made!), but the two times I ran it, it desieled for a good 2-3 seconds. I'm thinking it is probably the carb since it didn't do that before (except for once or twice that I can remember). Any ideas on what I can check/adjust to combat this problem?

Thanks!

Is your '76 Dodge truck carb off a slant-6 engine, or off a V8? Most of the V8s had idle stop solenoids by '76, and if yours is inoperative or improperly adjusted and hooked up, you can get dieseling, for sure. What's your idle RPM set at? Your base ignition timing?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The carb I have is off of a 318. If there is a solenoid, there would be wires coming from it, right? There were no wires on it when I bought it, and I can't find a spot where anything would plug in. From everything I can see, it looks almost identical to the super six carb.

I did rebuild it, and I thought I was careful. I hope I didn't mess anything up.

I don't yet have a timing light, and I've been trying to set the idle by sound so that it doesn't engage too harshly when I put the tranny in gear.

It also feels like it doesn't hold the rpms steady (cruising or idle)- there is a slight pulsation of a bit faster and slower. Would the valve lash have anything to do with this? Perhaps timing?

The symptoms you describe (dieseling on shutoff, surge on steady throttle) suggest a vacuum leak or other too-lean condition. Running too lean causes surging as you describe, and also causes the combustion chamber to heat up hotter than normal, which causes edges or bits of carbon (or the spark plug electrodes) to glow hot enough to cause dieseling on shutdown. Improper ignition timing can also cause or aggravate both symptoms. How's the idle quality?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

It seems to idle pretty good - when I made it richer it seemed to idle better. The idle smoothed out when I made it richer. I do have brand new vaccuum hoses to the distributor and to the valve cover. I'll check to make sure that all connections are sealed. Should I also try richen the fuel mixture by screwing the metering rods out? And when I was rebuilding the carb, I made an adjustment to the floats like the directions said. If those are set too low, could that make it run too lean?

Thanks so much for your input! I am definitely learning a bunch!

A too-low float will generally cause extreme surge at high engine RPMs and/or loads, not at low throttle or idle.

Be careful with your adjustments—it's easy to mask the problem rather than fixing it, by dumping in more fuel. I'd be checking carefully to make sure the manifold sealed correctly at all junctions (all six runners to the head, manifold to carb base, EGR valve itself if present, EGR valve or blockoff plate gasket, check for manifold cracks, etc) Is this an iron or aluminum intake?

What is your idle speed?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

For my idle speed - I don't have a tool to check that yet either. I think one of my neighbors has a tool that you can use to check the timing and the idle speed. I'll have to check into borrowing that. Like I said before, I'm trying to get the idle close by how hard my tranny engages when I put it into drive or reverse, but I know that's not exactly the right way to do it. I think the warm idle speed should be around 700 rpm, right? And what should the timing be set at?

And whatever I'm doing to my car, it's very easy to do it better than it was when I bought it. I took the old intake/exhaust manifolds off, and the intake manifold runners are visually further away from the engine than the exhaust runners, which would explain why my car ran like poop - so I was very careful to get the manifolds both sealed properly, although that doesn't necessarily mean I didn't make a mistake. It is an iron one, and there are no cracks or anything. I made an egr block-off plate, so I'll double check that to make sure it's sealing properly.

Also, as I am trying to get the carb dialed in, I maybe set the carb up a tad on the lean side. In trying to get it started, I think I put the metering rods a tad lower in the jets, and maybe I didn't turn the fuel mixture screws out as far as they need to be. But I absolutely agree with you, I definitely don't want to just keep pouring gas into the car hoping that will fix it.

man, sometimes I really get long-winded