Problem with my Rochester 4MV. On a 1974 Buick LeSabre Luxus, 455 CID. When the engine is started cold, the choke correctly engages, and the engine is in the high idle mode. Observing the Quadrajet with the air cleaner off, I observe the following: A dancing "sheet" of raw gasoline on the forward side of the rear wall of the primary air horn (just behind the rear edge of the choke blade). At first, I thought it might be condensing water, but I checked, and it's gas. The gas forms a film that seems to creep around on the air horn wall, but only while the engine is in the high-rev warm-up mode. The gas is no longer visible once the engine drops down to normal idle. The carb's stock, and fully functional (w/o the A.I.R. pump). Besides the visible gasoline, the only other problems are: throttle response seems alittle sluggish, and fuel economy isn't so good (not surprising for a '74). The primary piston does seem to move, and responds to vacuum variations in the engine (verified by placing a trimmed soda straw down the tube on top of the piston during operation). So, is this gas situation normal? If not, what's the fix? Should I get an Edelbrock Q-jet replacement before they're all gone?
First guess: You could trace the gasoline to two tiny holes in the air horn, one for each primary venturi. Some Q-Jets have this feature, some don't. When the choke is "mostly" closed, the air rushing past the two holes will pull additional fuel. Once the choke blade opens, there is no vacuum there, so no fuel flow. If you see those two tiny holes, what you describe is TOTALLY NORMAL. (Is the engine running overly rich? If not, you aren't getting too much fuel, and so the "sheet" of gasoline you see must be intentional.)
