How to set the IMS on an Edelbrock 1407 750cfm?

[FastbackJon]

Well my 440 Charger died the other day on the road as I was coming off the freeway. Floats stuck open, way too much fuel. The carb was all dirty and blackened inside from a previous carb fire and some backfiring.

Got the car home, took the airhorn assembly off and noticed one of the floats was not right. When positioned right side up it fell down too far. About 1.25 inches, where it should be between 15/16 and 1 inch. So I bent the tab on the back and set it back to specs. Also the float lever pin on that one had come out part way. Maybe it was like this, or maybe it came out when I took the airhorn assembly off? I don't know. I measured the floats at the stock 7/16 distance when the airhorn assembly is upside down.

I also cleaned out the carb throroughly while I had it open. There was little brown gritty stuff in the bottom of the bowls. No reason for this that I can think of since I have a filter before the fuel pump and it is a newer 440 (2000 miles) and new carburetor. Unless it is from the foam filter that burned when I had the carb fire when I had the triangular open top edelbrock air filter on it.
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Anyway to get to my problem, after cleaning out the metering rods too, I put it all back together and installed it back on the 440. I turned the IMS all the way in and backed them out a turn and a half. I started the car and then went to adjust the IMS and started to lean it out (clockwise). Even with them both all the way screwed in (leaned out) the car still runs. I'm having a real hard time hearing any RPM changes too when I adjust either IMS in or out. This is with the idle set at 850 rpms.

I want to get the carb set up properly and tuned so it is efficient, powerful and so it won't foul out plugs or waste gas, but I think something is not right if I can't kill it by leaning it out all the way with the IMS. Anyone know an edelbrock better than I do?

It is #1407, a 750cfm unit.

THANKS!

[Plumcrazy]

If turning the idle mixture screws all the way in have no effect, the engine is getting fuel somewhere else.  Possible the throttle blades are open so far the transfer slots are exposed.

Make sure the secondary blades are fully closed.
Also I would look down the carb while it was idling to see if fuel was dripping from the venturi's

[John_Kunkel]

Have you looked down the throttle bores with the engine running to see if fuel is dripping from the boosters? If they're dripping, the extra fuel will cancel the IMS settings.

The float lever pins are free to float sideways, when the cover is removed they can fall out but will be prevented from doing so when installed in the carb body.

[deputycrawford]

I also thought of it idleing on the main well instead of the idle circuit. A cam with too much duration will cause the Edelbrock carbs to need too much idle screw adjustment (like mine) and not meter the fuel correctly. Check for fuel drip while running and see how far the idle screw is turned and let us know. I also ask about the cam dimensions all the time. It is the brain of the engine and will tell us what to suggest with the rest of the package from our experiences. I called Edelbrock tech line and he told me to ditch my Edelbrock and go with something with lower vacum capabilities. I went with the Demon carb. Keep us informed.