I have a 1978 124. I removed the air compressor and EGR, ok in Mass. The manifold vacuum is steady at 23" at idle. When I crack the throttle under load it stumbles. I am guessing that with fewer vacuum devices, I now have more vacuum and the accelerator pump does not discharge enough gas to match the increased airflow. I have checked for leaks and and replaced the vac pump diaphram. The pump cam is set at its highest output and the nozzle is clean. The stumble persists.
How about I swap out the 32 ADFA with a replacement carb to increase performance? Any recommendations in the few hundred dollar range.
ADFA carb upgrade
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So Cal Mark
Re: ADFA carb upgrade
removing that stuff has no effect on engine vacuum. The pump volume is controlled by the size of the nozzle on a Weber. Does your timing advance work when you accelerate the engine?
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dcarey
Re: ADFA carb upgrade
The mechanical advance appears to work properly (I can see the timing mark move when I increase the RPMs, also I disassembled the advance and lubed it, to be sure it worked freely). The distributor has no vacuum advance (by design). Any idea what compensates for a lack of vacuum advance?
The engine only stumbles (it feels like a very distinct mis-fire) on acceleration, it runs ok at any RPM once acceleration is completed. I replaced he accelerator pump and cleaned the nozzle. I can see a very strong stream of gas delivered from the nozzle when any pressure is applied to the acclerator pump.
The engine only stumbles (it feels like a very distinct mis-fire) on acceleration, it runs ok at any RPM once acceleration is completed. I replaced he accelerator pump and cleaned the nozzle. I can see a very strong stream of gas delivered from the nozzle when any pressure is applied to the acclerator pump.