MTFCA Forum

Consulted the service bulletins last night. I found 2 different published float setting dimensions.
The typical view with a dimension of 15/64" (<1/4") Top of float to machined bowl surface.
The second dimension comes in a mention of the vaporizer float. It is stated as 1/4", "exactly the same" as the previous carburetor.
Could this be a deviation specifically for the improved car & the extra head pressure on top of the larger float???
1/64" isnt much, but, the fuel level is critical to a good running carb @ idle & hi speed functions. And enough so to make mention of.

I have always gone with 15/64”. They may have rounded it off to 1/4” since many rulers do not measure 64ths. It is best to make a 15/64” spacer gauge using a razor blade that measures from the machined flange to the top of the float. Jim Patrick

For better or worse, I set the float so it's top surface is parallel to the machined flange of the carb body. (Judging by eye.)

I would be surprised - and very impressed - if you can measure that 64th. The lever on the float probably bends enough to make that difference if you invert the carburettor.
How much force do you apply to the float when you push it up to make the measurement?

But I also doubt that it noticeably affects the running.

No upward pressure should ever be applied to the float to bend the tang. Using needle nose pliers, bend only the tang portion attached to the float that makes contact with the end of the needle. Jim Patrick

The difference between 15/64" and 1/4" is 1/64". Is that enough difference to really matter?.

Steve Jelf wrote: ↑

Thu Nov 18, 2021 1:50 pm

The difference between 15/64" and 1/4" is 1/64". Is that enough difference to really matter?.

I'd be genuinely surprised if it did.

Generally, parallel to the carb body is fine. If you're putting around town looking for ice cream, and using your shut-off valve like you should for stops of any length, you're good to go.

If you're running a commercially available float valve, you're going to run the carb bowl low of fuel at speeds over 35MPH or going up long hills anyway. And if you're using the crummy fiber washer that comes with the valves, you're weeping fuel into the bowl while it is just sitting there and your starting fuel level will invariably be totally screwed up anyway.

If you have a viton or neoprene needle, you will get a slight movement of the needle when it is up, however with the steel needle, it stops when it hits the brass.
Norm

Scott_Conger wrote: ↑

Thu Nov 18, 2021 5:53 pm

Generally, parallel to the carb body is fine. If you're putting around town looking for ice cream, and using your shut-off valve like you should for stops of any length, you're good to go.

If you're running a commercially available float valve, you're going to run the carb bowl low of fuel at speeds over 35MPH or going up long hills anyway. And if you're using the crummy fiber washer that comes with the valves, you're weeping fuel into the bowl while it is just sitting there and your starting fuel level will invariably be totally screwed up anyway.

None of those downsides have happened yet. Keeping my fingers crossed

I’ve never been real fussy with the Float Level and usually set it level when the Carby is held upside down.
Never use force to close the needle onto the seat. I’ve seen Blokes push the float upwards to bend the tag to achieve a level setting. This has the potential to damage a standard needle and seat and wreck the Viton tipped upgraded Valve.
Fibre washers are crap and I use a O Ring successfully but Scott’s upgraded version of the valve and washer is the way to go!
Alan in Western Australia