Setting fuel level v float level

[barney01]

Today I set my carbs FUEL level instead of the FLOAT level. The argument is that the fuel level is set with the carb upright and assembled so in the full operating position. The measuring tube is screwed into the float bowl drain screw socket. I rigged up a temporary fuel tank ( I used a large oil syringe with the plunger removed) which I hung up above my bench. A length of petrol hose from it connected to the assembled carb set on the bench. I then filled the syringe tank with water (much easier to use than petrol) I then held the measure tube against the carb body with a cable tie. Then I marked the measure tube the top of the float bowl and 4.5mm down the minimum level. The ideal level is 3mm down with 2mm the maximum. Then it's just a case of adjusting the tang on the float to achieve the desired level. When the level is set leave connected for five minutes or so just to confirm your float level needle valve is doing its job and switching off the flow.
I know it's a bit of a faff but I like this method better. It is easier to do than it sounds!

[slosher]

Barney
My thoughts on that method would probably be more precise,it is widely used on the Britbike forum with Amal carbs surely there must be a variation in the actual die cast thickness of the bowls
But is it the height or the actual volume of fuel any ideas guys

Cheers Dave

[barney01]

Dave I think it's the height of the fuel that is relevant. As you know the float bowl on this carb in vented externally so as the apply atmospheric pressure to the surface of the fuel. The engine draws air through the venturi above the jets making lower pressure and therefore fuel is pushed up through the jets. So if the fuel in the bowl is too high, too much petrol into the venturi engine runs rich. Fuel in the bowl too low not enough petrol into venturi engine runs lean. Well that's my understanding anyway

[Kevine6959]

Good description to an age old problem

Thanks