Fuel Flow Rate

Tried with the gas cap off - no de france.
This is a freshly rebuilt engine with new manifold and gasket. I put about 20 miles on it without much complaint before the body went into the shop.
And yes, I was thorough in creating good grounds when putting it all back together.
 
Hi Car,

Per response # 20, Model A's have many trees to tap; another tree to tap:

"This is a fresh rebuild of everything except the carb."

Could you possibly try another carburetor on the rebuilt engine to see what happens?
 
I snuck the rpm up slowly on the column and pulled the choke out about half way... RPMs increased, so I went back into the carb.
I poked a twist tie into the channels to make sure they were all clear. I found some blockage in the channel between the bottom of the choke adjustment and the jet.
What a difference that made... but still not fully resolved. Now I can rev the engine without it dying and I can drive it out of the driveway, but still can't get into 2nd gear before I start hearing backfire in the carburetor. The air adjustment needle is still fully seated on the carburetor.

I plan on trying a different carburetor to see if it fully resolves the issue and I'll check the timing (again) to make sure nothing has slipped.

Thanks for all the ideas. We are getting closer.
 
Another frustrating Saturday trying to get my A to run...
Bought a new carburetor and put it on... Same behavior.
Went back through the fuel lines with a small gun barrel brush...No change.
Checked the timing... dead on.
Checked for leaks at the manifold. No rpm change.
Plugged the vacuum hole at the manifold with my finger. Vacuum felt fine and the performance didn't change.

Sincerely frustrated at this point and I am too far out from a local club to get someone to drop in and diagnose this with me.
 
It sounds like you have decent fuel flow to the carb and given the fact that you have now demonstrated the problem with TWO different carburetors, AND how rapidly the problem seems to happen... even before it is warmed up if I understand correctly, I would suggest that since most carb problems are really ignition, I would go back to a stock ignition system if you can and see what happens. Your symptoms are common to a bad condenser or a bad coil. At the very least, I'd check those two next.

Steve
 
Check to be sure that your fixed point in the distributor is tight after the locking screw is tightened. I had a problem with my fixed point block which allowed the fixed point to turn and move around even thought the locking screw was tight. This may be a shot in the dark but it is easy to check. I replaced the fixed point block and the problem was fixed. I identified the problem by using a VOM meter to check the voltage across the points while I hand cranked the engine. The voltage level was very inconsistent. Good luck.
Supergnat
 
I disconnected the fuel line going into the carburetor yesterday and found the compression fitting there was slightly twisted. It wasn't distorted enough to leak fuel, but I replaced it anyway. After that change, the car ran as well as I've ever seen it. Mitch mentioned the fuel line being pushed too far into the carb. Not sure if that was the case, but I can say I got it out on the road and discovered 14 other unrelated things that need to be improved.

My enthusiasm is restored. Thanks for scratching your heads with me on this one.
 
car pit said:
i disconnected the fuel line going into the carburetor yesterday and found the compression fitting there was slightly twisted. It wasn't distorted enough to leak fuel, but i replaced it anyway. After that change, the car ran as well as i've ever seen it. Mitch mentioned the fuel line being pushed too far into the carb. Not sure if that was the case, but i can say i got it out on the road and discovered 14 other unrelated things that need to be improved.

My enthusiasm is restored. Thanks for scratching your heads with me on this one.
Click to expand...

great news!!!!
 
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