17-07-2018, 01:38 PM
Hello
Guidance and opinions please.
1937 Ruby. It will start on the handle or button cold or hot but has a large flat spot on initial press of the accelerator pedal which will stall the engine unless extreme clutch and throttle feathering takes place. If I pull out the choke the flat spot almost disappears pointing me to fuel mixture issues.
Using carb cleaner on manifold joints or carb body/ spindle does not change engine note so no apparent air leaks.
The air screw on the professionally overhauled Zenith has no effect on either the idle or running of the engine.
Underneath the carb I removed the blanking screw and find that the compensating jet looks a tad mangled, i.e. the majority of it is missing albeit there still appears to be a small drilling at the bottom. See attached image.
On top of this I also fitted a fresh dynamo and have found there to be excessive float/lash between the cam gear and dynamo which is also excessively noisy.
My questions are;
1. Does the air compensation jet need the be completely intact for it to function correctly?
2. Why does the air screw not change running conditions?
3. The excessive play in the dynamo must cause play at the distributor end. Is it possible this is where the flat spot emanates from?
4. Will lapping the cam gear remove the lash between dynamo and cam gear ?
Apologies for so many questions. Still.learning.
Cheers in advance.
Dave
Guidance and opinions please.
1937 Ruby. It will start on the handle or button cold or hot but has a large flat spot on initial press of the accelerator pedal which will stall the engine unless extreme clutch and throttle feathering takes place. If I pull out the choke the flat spot almost disappears pointing me to fuel mixture issues.
Using carb cleaner on manifold joints or carb body/ spindle does not change engine note so no apparent air leaks.
The air screw on the professionally overhauled Zenith has no effect on either the idle or running of the engine.
Underneath the carb I removed the blanking screw and find that the compensating jet looks a tad mangled, i.e. the majority of it is missing albeit there still appears to be a small drilling at the bottom. See attached image.
On top of this I also fitted a fresh dynamo and have found there to be excessive float/lash between the cam gear and dynamo which is also excessively noisy.
My questions are;
1. Does the air compensation jet need the be completely intact for it to function correctly?
2. Why does the air screw not change running conditions?
3. The excessive play in the dynamo must cause play at the distributor end. Is it possible this is where the flat spot emanates from?
4. Will lapping the cam gear remove the lash between dynamo and cam gear ?
Apologies for so many questions. Still.learning.
Cheers in advance.
Dave
