carb floats

[Mikey]

I am in the middle of a carb overhaul,(twin ZS-175); and discovered this oddity. After finishing with the first carb, I proceeded to disassemble the second carb for cleaning. I immediately noticed upon removing the float bowl that the float was installed the opposite side up (or down) from the first carb float. If you have ever done this you will know that the float has one flat side, and an jagged or 'tapered' side for lack of a better description. So now I have one float with it's flat side down, and the other with it's tapered side down. Which orientation is the correct one? With the carb body turned upside down to measure the float height, I believe I should be looking at the flat side of the float according to the crude diagram accompanying the carb kit I purchased.

[Ferris]

The "flat" side of the float should face down, toward the bottom of the bowl.

Measuring from the gasket surface with the carb upside down, the float should sit 16-17 MM (5/8 - 11/16" for us fractional types) high, measured at its highest point, which will be near the pivot pin since the float will be drooping at the other end a little bit when set right.


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Kevin Anderson
1980 TR7 DHC
1974.5 MGB GT
1990 Jaguar XJ40

[Underdog]

Ferris is correct. Just did a set on a TR6. You may already know this but give them a shake and listen for fuel inside. I inherited the TR6 from another shop that had rebuilt them & couldn't get it to run. Found float half full of fuel.

72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.

[Hasbeen]

It seems that Zenith floats often get petrol in them by osmosis, &
do not have a hole or split in them. There is a poor mans trick,
with a float with petrol in it like that.

You probably know that wood swells when wet with water. Dry wood
can be shoved into a hole in a boat, or tank. It will swell as it's
soaked with the water, & seal the hole.

Well, it works with petrol just as well.

I had a Zenith float that was quater full of petrol, & causing
flooding, as it was not shutting the needle.

I could not wait for a float, so I drilled a 3/32" hole in it, & got
the petrol out. The only bit of wood I could find at the time was a
kebab stick, so, although softer wood would have been better, I
tapped the point of that into the hole, & cut it off, with a 1/16 or
so left proud.

I meant to replace the float, but it was still there a year later
when I sold the car.

The young bloke who bought it used to come & get bits from my spares
car, & never mentioned any carb problem in the next 3 years. I had
forgotten this "bodge" until this topic came up.

Hasbeen

[Underdog]

FWIW, The new floats I got from Moss were in my opinion, an improved design. Instead of the metal float arms entering the plastic float, the floats are molded with a solid tab to which the arms are riveted. Sort of hard to explain, should have taken photos. Anyway, I suspect the fuel entering at the point where the metal entered the float on the original design.

Hasbeen, another trick is to heat the float with a hair drier. The fuel will expand and the hole become apparent. I fixed a brass float for the fuel sender in my old Ford truck that way. Of couse it was simple to repair the brass with a soldering iron. I wasn't being thrifty, a new unit was NLA.

72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.