I have an F800 with a 429 in it. Since I have bought it, I have got it tuned good, except on spot in the rpm range. The truck accelerates strong through the gears, and runs good at WOT(wide open throttle). The issue lies when you back out of it just a little, the engine will begin to flutter and fail, and loose speed. If you stand on it, it will rev right up strong again. This happens at about 3200 to 3500 RPM. The original carb has been taken off and I put an Edelbrock 750 on it. It has good idle and revs up strong when you are accelerating. Its when you are on flat ground and wanting to go 55 at a steady pace the problem arises. I richened up the primaires by putting in a smaller diameter metering rod in it and a stiffer actuating spring. That didn't make any difference. Also wondered if my Vacuum advance was bleeding down, so I replaced that, and that didn't make any difference either. It acts almost like it has a rev limiter in it and the ignition is being cut off very rapidly, but as soon as you stand on it, the problem disappears. Any Ideas? Thanks for any and all help.
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