Finally got sick of fighting the 4350 carb my '78 f250 and bought a new Edelbrock for it. I wanted a 650 CFM carb, as the 4350 on paper flows 715 CFM. In reality, I doubt it did that, but I wanted something a bit bigger than 600 CFM, as I have a 460 engine. I ended up getting one of the new AVS2 carbs with a manual choke, model 1905.

I mated it to a Transdapt 2198 speadbore to squarebore adaptor plate and also purchased the tranny kickdown bracket from Edelbrock. The installation was not entirely trouble free, as the adaptor plate, as shipped, would cause the secondary butterflies to bind. Also, the tranny kickdown linkage is slightly moved from its original centerline, causing the need for some fiddling and fussing to make it all work smoothly. After a fair bit of grinding, filling and polishing, everything works smoothly, and buy what a difference.

Off idle performance is fantastic, as is the mash-the-gas secondary kick. The carb has transformed the drivability of this truck and I am very happy with it. Initial MPG for a 28 mile shakedown cruise, half highigh, half city streets, wad 11.3. I suspect I was running a bit rich, so I'll report back over time how it does.

2 small complaints I have. The fast idle cam is only in play when the choke is almost fully closed. I'd prefer if it came off a bit more gradually, so that it would keep the revs up slightly when partial choke was on. Second, I find that I have to give a very slight amount of throttle when starting while hot. This could be the idle mixture screws being too lean, but they were set using vacuum gauge and RPM. I can live with both of these though, and overall an very pleased with this carb.

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They're pretty good carburetors. I was really impressed when I switched from a 4150 to AVS2.

Have you tried adjusting the fast idle screw to fix that issue? Mine needed adjusting in the opposite direction from yours. The hot start thing could probably be fixed. I always say to everyone running a carburetor, install a AFR gauge for tuning. It takes all the guess work out of tuning. And use a vacuum gauge to set your idle mixture screws. Vac gauge is inexpensive and easy to use. AFR gauge costs a bit more and requires a little work to install, but it's literally worth it's weight in gold.