T140 Running Rich

[RobinV]

I am running rich with the Amal Mk 2s. Very rich. I can see the black unburnt fuel smoke at the exhaust at idle even with the screws turned down to 3/4. Runs strong, but after 10 miles or so, it craps out and runs poorly. When I return home, I see that my plugs are black fluffy, and I notice the fuel level is down demonstrably. I have the needles at their lowest level.
Pulled the carbs. The floats are floating, and the mains are 220 I believe. It always starts first kick every time w/o enrichener activated. Wondering if I should block the hole to the float bowl with a thin piece of rubber so as to rule out any fault there. Any pointers appreciated. Looks like float adjustment is not possible.
Thankyou, Robin.

 

[Rudie]

always starts first kick every time w/o enrichener activated.

Have you checked the seals on the ends of the enrichener plungers? They go nipple-shaped and don't seal, cause the symptoms you have described.

If you fit new enrichener plungers, you will probably need to reverse all the previous 'adjustments' you made ...

mains are 220 I believe.

Should be marked on them.

Looks like float adjustment is not possible.

If the carbs have black "Stay Up" floats, their height on the fuel can be adjusted by bending their pivot 'tangs" (if bending opens up a 'tang' pivot sleeve, close it carefully with pliers).

If the carbs still have yellowed white hollow floats, while their height can be adjusted by warming the bowls in boiling water then tapping the brass float needle seat up or down with a wooden dowel drift, those floats are susceptible to ethanol, should be replaced with Stay-Ups. Plastic float needles should be replaced with Viton-tipped aluminium ones.

However, float height should not be adjusted on its own, Amal recommends checking the fuel level in the bowls, adjusting as necessary. Fuel level checking procedure documented on the Amal website. Float height is then a function of correct fuel level.

 

[RobinV]

Thanks Rudie. Great advice. Yes, both of the enrichener seals are nipple shaped. I have one on the table here. Looks to not be a removable rubber part so I will order two new assemblies. I have the old floats also, so should upgrade.