Quote:
Originally Posted by Bob Bidonde
This slide may help you.
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I respectfully disagree with all of these statements in this posted diagram.
1 - gasoline slashes forward in the float bowl.... why would this be a problem as fuel moving forward is no different than going downhill... Do model A's stall going downhill?
2 - car noses downward... same thing as driving down a hill.
3 - main jet and cap jet ingest air ... These high speed circuit jets are not in operation when the throttle plate is closed and the carburetor is on the idle circuit while stopping. Fuel moving forward in the bowl can only go so far, it will not move enough to uncover the bottom ends of the main or cap jet.
4 - inrush of fuel as the float moves downward... just the opposite happens as you tip the carburetor fuel moving forward and up is going to push the float up, closing the fuel inlet valve.
5 - car recovers and too much gasoline in the float bowl... where did this extra fuel come from and what difference would it make? When transitioning back to the idle circuit the engine is stalling because it's lean not because it's too rich.
The fuel inlet valve float valve and float keep the level high enough even while stopping and some amount of fuel moving towards the front of the car the jets are always covered and supplied with fuel, especially when transitioning back to idle as very little fuel is being consumed.
This diagram is very misleading. Try holding a glass of water and stopping in Model A, You will not see fuel move this drastically, they would've put baffles in the bowl if it was possible to uncover the jets while stopping.
The fuel being only 5/8" below the gasket line and the volume of the float bowl will not allow the Jets to become uncovered.
The arrow showing fuel or air moving backwards through the idle jet is impossible carburetors work on vacuum and when you're on the idle circuit, engine vacuum on the jet would be pulling fuel into the throat of the carburetor. Fuel moving forward isn't going to pull a stronger vacuum on the Jets.
The stalling issue can also happen with model B carburetors with both styles of float which are turned 90° from the Model A design, further proving that fuel moving in the bowl is not affecting the Jets, fuel inlet valve or float.
Why was none of this happening back when the cars were built?
They never would've sold a single car if this was an issue, there would've been Ford released service bulletins addressing the problem.
At any rate, I'm not trying to stir up trouble or cause problems but I think more thought needs to go into this before it's published.