Update - solved it. Turned out it was the carbs. Disassembled, cleaned and reset them according to the specs. Fired right up. Set timing to 10 BTDC with no vacuum. Interestingly, I can only hit 10 BTDC on the crank with the distributor turned virtually to the maximum counter-clockwise.
The carbs need major overhaul. Only half an accelerator pump is working (ie: front carb nozzle is completely plugged and the rear carb has a wimpy stream), leading to some nasty stumbling. Acceleration is very smooth after that. Anti-stall vacuum capsule is MIA so it sometimes stalls coming to a stop with idle set to 800 rpm. The secondary diaphragm is also not holding vacuum on either carb, leading to a "speed limiter" effect around 50 mph (80 kph).
If anyone has old, straight, re-buildable Zeniths with no parts missing or seized around, I'm interested. If not, I will consider a professional rebuild or a set of Webers.
Thank to all who chimed in, your suggestions were very helpful in guiding me to the solution.
11-25-2014, 10:54 PM
Linear Mode
