Model B engine question

E

ekentner1

Junior Member
I am running a Model B touring engine in my 28 Phaeton. The engine is new, about 200 miles on it now, but it has a problem that is giving me a fit. Every time I step on the throttle, the engine hesitates, then "catches". It makes down shifting a chore, and driving a Royal Pain.

The engine is a balanced B with pressure to the rods and mains. I'm running a 7:1 Winfield head, headers, touring cam, and dual 97 downdrafts. I'm also running an FSI electronic ignition. The 97s are "new" rebuilts.

So far we've tried riching the mixture using the idle adjustments screws, and have tried changing the timing, but nothing seems to help. Anyone have any ideas?
 
The symptom you are experiencing typically is due to not having the accelerator pump(s) adjusted correctly. or not working properly.
If memory serves, it is the lever over the top of the float bowl and presses a pump down thru the top.

With the engine not running, you should be able to see a stream of gas inside the venturi when the throttle is opened. Fuel enrichment to minimize the stumble when velocity loss thru venturi.
 
With the engine OFF, look down the carbs.
Move the throttle very slightly. Gas should squirt from the pump nozzles. (all 4)
If it doesn't or you have to move the throttle quite a way, you probably have a pump linkage adjustment problem. Sometimes they get bent and a rebuilder might not check it.
If no gas comes from the nozzles, you have plugged passages in the carb body. I have seen carbs that were so called "rebuilt" where they did not pull the lead balls from the passage ends to clean them out.
 
The hesitation you have is common with Stromberg carbys lean just off idle there are 4 common fixes try 1 at a time
1 Accelerator pump try the winter position (more fuel)
2 Set Float level (may be low)
3 Idle jet tube try the next size up
4 Advance the timing a few degress
 
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