Float adjustment question for Weber 40 IDA

[steve911T]

Rebuilt the webers for a 911T and had a question about the float adjustment. I have the float tool which screws into the side of the carb and was wondering where the level of Gas was supposed to be after it filled up. There is a top line, about 1/2 inch from the top and and a line about 3/4 of an inch lower. I am using the top line to adjust the float level. This should be right according to the miserable instructions that came with the tool (18 years old). I also noticed that when the engine off, ignition on, there was gas slightly dripping out of the accelerator pump nozzles down in the carb, is this right? Did not seem like it was.
Thanks for any help that may be given.

[austin552]

Your gauge should have two lines at the top and two at the bottom. The fuel level should be between the top two lines.

[steve911T]

Great, that is what I did. Thanks for the reply.

[911K]

Fuel is not supposed to be dripping out of the accelerator pump nozzle at any time. You may have a needle & seat that is not closing completely or the float level could be too high.

You should be checking the float level with the engine running. Adjust the height of the float level with the washers in the kit, not by bending the tab on the float. The tab on the float is just for adjusting the drop of the float in the bowl.

If your needle & seats are not sticking, try adjusting the level to the bottom of the two upper lines and see if that helps.

[rfn026]

I have a whole Weber section on my site. You might want to take a look at it.

Richard Newton
Porsche Race Car Files

[austin552]

I seem to recall 101 Projects having some good adjustment info.

[911pcars]

Fuel from the accelerator pump or from the main discharge nozzle? The fuel path is different for each.

Fuel delivery (basically a timed squirt) from the accelerator pump jet should only occur when the throttle linkage moves open. Fuel delivery is by a mechanical diaphragm. If the linkage doesn't move the diaphragm doesn't move. In addition, the jet is above the venturi where there is little or no vacuum signal at idle.

Fuel from the main discharge nozzle is controlled by the float level and the vacuum signal generated by air passing through the venturi. At idle, air flow should be insignificant and thus no fuel delivered from here until well into part-throttle unless the fuel level is too high.

Adjust the float level to lower the fuel level and see what happens.

Sherwood

[steve911T]

Thanks for the replies. I will reset the float level down a bit and see what happens. It was set to the top of the top line, maybe down a mm or two will correct the problem.

[shbop]

Anyone know why the "sight-glass" wasn't made from clear material? Trying to see the level between the top lines, on a runnig motor, is hard enough.