Zenith Stromberg Running Lean - Update
Since my inital post, I've done quite a bit of work, but still have the lean mixture problem based on the lift the piston test and driving. I rebuilt the carbon cannisters to address the charcoal in the anti run-on valve and put the old mixture needle back in as suggested, but it's still running lean based on lifting the piston (almost stalls with minimal lift). In the meantime I put in new points, distributor cap and condensor and set the timing at 15 degrees BTDC to no effect. After all this, it does idle smoother & consistently, but you can still feel the hesitation at speed while driving. I can't find any vacuum leaks using carb cleaner and pulling the vent line to the carbon cannisters doesn't change the idle as it did before. I also adjusted the mixture needle all the way clockwise to no effect.
I've run out of options to try next. Thanks for your advice.
Since my inital post, I've done quite a bit of work, but still have the lean mixture problem based on the lift the piston test and driving. I rebuilt the carbon cannisters to address the charcoal in the anti run-on valve and put the old mixture needle back in as suggested, but it's still running lean based on lifting the piston (almost stalls with minimal lift). In the meantime I put in new points, distributor cap and condensor and set the timing at 15 degrees BTDC to no effect. After all this, it does idle smoother & consistently, but you can still feel the hesitation at speed while driving. I can't find any vacuum leaks using carb cleaner and pulling the vent line to the carbon cannisters doesn't change the idle as it did before. I also adjusted the mixture needle all the way clockwise to no effect.
I've run out of options to try next. Thanks for your advice.