<VV> Carburetor mystery

[Kenneth Schifftner]

Brian:

Have you checked the spark plugs after a failed start? Wet? Dry? Getting too much fuel?

I went through some old carburetor references and when the throttle butterfly is “closed” (just the small notch is open), the manifold vacuum controls. When the throttle is cranked open, the idle circuit changes to the “off idle” circuit. That fuel emission mixture starts at the fuel cluster but then passes through the body of the carburetor over to the slot area located above the idle mixture chamber.

You mentioned the idle circuit was cleaned. Did you pass a fine wire through it? Just chemical (carb cleaner)? Other? I’ve heard that the passageway sometimes needs to be “reamed” out with very fine wire. I’ll look for that article.

My understanding is that the engine fired but once you opened the throttle the engine died. That would indicate a problem with the off idle passages as others have mentioned. With an enlarged main venturi, it sounds like the off idle circuit is not allowing the transition to the functioning of the mail venturi.

Maybe “clean” isn’t clean enough for the passage of the fuel emulsion through the carburetor body from the siphon tube to the chamber above the slot.

Ken Schifftner