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+--- Thread: Ruby throttle hesitation. (/showthread.php?tid=1458)
Ruby throttle hesitation. - Pricey - 17-07-2018
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
RE: Ruby throttle hesitation. - Martin Prior - 17-07-2018
Is the throttle butterfly spindle worn, allowing air to leak in?
RE: Ruby throttle hesitation. - Pricey - 17-07-2018
Hello Martin
It appears not. I've sprayed carb cleaner around it in both closed throttle and the initial throttle open position and do not get the expected change in engine speed.
Cheers
Dave
RE: Ruby throttle hesitation. - Ruairidh Dunford - 17-07-2018
What size jets do you have?
RE: Ruby throttle hesitation. - Pricey - 17-07-2018
Hello Ruairidh
I've attached an image of the jets.
You will have to stand on your head to view it mind such is my skill at photography and with mobile phones.
Cheers
Dave
RE: Ruby throttle hesitation. - Ruairidh Dunford - 17-07-2018
They are all correct - but may be worn. Do you have others to try and do you have a fibre washer beneath the main and compensating jet?
Is the flange, where it attaches to the inlet manifold, stamped with a 7?
RE: Ruby throttle hesitation. - Pricey - 17-07-2018
Yes to washers and number 7 but no to spare jets to try.
RE: Ruby throttle hesitation. - Ruairidh Dunford - 17-07-2018
You could try a richer compensating jet - if you can get one.
RE: Ruby throttle hesitation. - morrisminor - 17-07-2018
Ruaridh, do you need fibre washers under the jets as my 37 doesn't have them ?
RE: Ruby throttle hesitation. - Ruairidh Dunford - 17-07-2018
They should be there, if none (and still working) you may be lucky.