MTFCA Forum

Hi All,
I would like to hear from people as to how to accurately measure the float level. I've read everything I can find and was wondering:
Do you measure the 1/4 inch from: A. the machined lip of the carb body (where the bowl gasket would sit), or B. from the edge of the casting at the corner?
Seems that there is the difference of the thickness of that gasket in measuring one way rather than the other. Maybe this is knit picking, but "Inquiring mind's want to know".
Thanks,
John
And oh, By the way: I found out why my carb was flooding. I rebuilt this carb about 2 years ago and only tried starting it this month. I was missing the spray nozzle. Ummm.... a major carburetor part that was sitting in a box of carb parts. Anyone ever forget something like that?

That measurement is no more critical than turning it upside down and eye-balling that the float is parallel to the carb flange.

In an earlier post to you, I stressed the importance of the shape of the lifting tab on the float and how it interfaces with the needle...if you have not read that, it is worth taking a look.

The service manual shows how & where to measure this gap. Its sans gasket.
The float setting is a starting point. The fuel level may need minor adjusting to get the mixture optimal @ idle & @ the same setting hi speed.
After fine tuning, the mixture screw need not be touched again unless driving in a change of elevation.

I was missing the spray nozzle. Ummm.... a major carburetor part that was sitting in a box of carb parts. Anyone ever forget something like that?

Yep. My 1923 touring ran into the ditch and suffered a broken wheel and a crunched fender because I forgot a cotter pin. It's good to pay attention.

The fuel level may need minor adjusting to get the mixture optimal @ idle & @ the same setting hi speed.
After fine tuning, the mixture screw need not be touched again unless driving in a change of elevation.

100% correct, and is always new news to those who insist you MUST fiddle with the carb to make it run at all speeds....you really shouldn't have to...the NH is a self-regulating device so long as the float level is correct as John said. Once or if it is determined that the carb needs further enriching or leaning at speed, that should be dealt with via float level tweaking. Some folks never drive their cars hard enough or long enough to even worry about it. If an NH is insensitive to float level or absolutely must be fiddled with regardless of float setting, it a sure indicator of a compromised low-speed circuit and requires passages to be cleared out.

In early NH literature it was advised to TIGHTEN DOWN the adjustable needle collar to a fixed setting, after finding said "sweet spot". I suspect that what had to be unexpected MILLIONS of cars/carbs sold, that advice went to the wayside with the massive influx of driver/owners who through sheer numbers could not be herded or coached into a fixed setting.

Admittedly, enriching for starting aids ease of starting, but regardless of that, once re-adjusted back to where it belongs, it shouldn't require further fiddling.

One thing I had happen with a NH on a tour many years ago was when it flooded and wouldn't start. I tried adjusting the needle, but still flooded. Another person on the tour asked me to remove the bowl from the carb and we found the jet had come loose. So be sure it is tight. It is located right in the center of the carb and the screwdriver slot is toward the bottom, so it is easy to fix if you know where to look. It can be fixed without removing the carburetor.
Norm

Here is picture of a measuring tool you can make from the rigid paper of a Manila file folder. Cut using a very sharp razor blade. Measure from the flange to the top of the float opposite the hinge. Jim Patrick

How about using a 1/4 inch drill bit to measure the gap b/w base and float top?

Or how about a ¹⁵⁄₆₄" drill bit?

That'll work

A round drill bit won’t work. You must measure from the flange and a bit will not seat on the narrow, recessed flange. The best way is to make a rigid paper measure that will seat on the narrow flange surface. If you don’t measure from the flange, your measurement will be about 1/32” too wide, meaning the float will not close the valve, stopping the flow of gas, when the bowl is full and the float is raised all the way up. Jim Patrick