Tillitson Carb Adjustments

[Relvis P. Johnson]

How do I set the needle valve adjustment and float level so I don't end up with gasoline on my garage floor?

 

[JOES31]

First replace the needle valve with a viton valve. I got mine from Macs. Turn the top casting upside down and set the float to 1" from the top edge of the casting with the gasket on to the bottom of the float which would be the top of the float when you are looking at it upside down.

I set the idle very low and turn the needle CW and CCW to the highest rpm that I can get and leave it.

 

[Relvis P. Johnson]

Thanks Joe!

I'll give it a go. Is there an adjustment other than bending the float to get the 1" needed? I had a brand new carb and it leaked internally. The shut off valve at the gas tank leaked a little, but I could not stop the carb from leaking. I traded the carb back to the source for another one and thought I'd better get it right before I install it.

 

[johnbuckley]

Thanks Joe!

... Is there an adjustment other than bending the float to get the 1" needed?....

... in a word "No"!. Check all the gaskets internally are good. I have found even brand new float valve of whatever type may leak ... they all need checking.

 

[Purdy Swoft]

More gaskets can be added under the float valve to change the float adjustment without the need of bending the float. Many model A venders sell an asortment of gaskets of various thickness for this purpose. All of the cutoff valves that I have seen will continue to allow gas to continue to leak past the valve and into the carburetor. If there are leaks caused by the float valve being too lose or a bad gasket or whatever, The gas level in the carb will increase untill it leaks. Most probably leak to some extent. Model A's are old and most repro parts are not as good as original parts. With gravity flow and a leaky cutoff valve, there will always be head pressure at the carburetor.