I bought this carburetor at a swap meet. It was rebuilt. It had a gros valve in it. The carburetor dripped gas. I replaced it with a new needle and seat. It still dripped gas. The outside of the carb would be damp with gas after it was parked. When cold the car started and ran just fine without even using the choke. But when it was warmed up, it would not start but needed to pull the throttle all the way down because it flooded.
I have adjusted this to 3/16" float level according to the book each time and it leaked.
Saturday I got fed up with it and crawled under and drained the carb then adjusted the float level lower. I don't know just what the level is except that it is lower than 3/16". I drove the car around and it ran fine uphill, down hill and on level. Then I parked it. Yesterday, no sweating , no drip.
Anyway what I think is that all brass floats are not the same. The height of the top of the float is not as important as the height of the bottom of the float as it is the bottom which floats in the fuel. So for those who have a constant problem with the carburetor leaking, you might try lowering the float level and see if that fixes the problem.
I've always adjusted NH floats to be 1/4" measured 180 degrees from the hinge and never had an issue. I don't have a book that tells me any different. I just know it works.
Many of the new brass floats are made in India and are heavier than the old ones. Pressure on the valve is a combination of fuel weight, float weight and size and float height. The new fuels are lighter than the old gasoline, which also causes less pressure on the float. The displace the same volume but do not place as much pressure --- think about it.
"They" not "the."
I thought the MTFCA Carb handbook recommends 15/64 th when using the brass float.
If you are using a stock float that will work. Get your handy dandy little Gold balance scale out and measure the difference in a stock float and several of the new ones made in India. The amount of solder on them varies greatly and they must be using a high lead solder as opposed to a high tin solder because they are heavy -- or not. The heavier they are the less they float. The brass they are using, if it is even brass, is also heavy by my observation although I have never taken the time to take one apart, remove the solder spills inside the seams, remove all the sloppy solder on the seams and the heavy hinge pin and measure the weight. No enough hours in the day to keep up with all of it.
Combined with the crap needle and seat sets the vendors sell and it is a wonder there are any NH's that actually run pretty well.
I stand corrected. Tony was right it is 15/64. That is what I set it and it leaked. I just crawled under and lowered it a bit without measurement and now it does not leak.
1/64th is .0156 or 15 and a half thousanths. That is about the thickness of a playing card. If that is going to make a difference in whether it leaks or not -- there is going to have to be somebody besides me working on NH's. I can't set a float within .0156 by bending a brass tab.
16/64ths = 1/4 inch.