This is what The Carburetor Shop (http://www.thecarburetorshop.com/Troubleshooting.htm) has to say:
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CORK FLOATS
Many of the less expensive carburetors from the beginning up through about 1940 were originally equipped with floats made from cork. Most of the floats were coated with orange shellac, and then the finish was baked, creating a finish fairly impervious to the gasoline of the day. A few of the manufacturers did not coat their floats, and used a cork material that seemed to work fairly well with the gasoline then being sold.
The gasoline of today cuts orange shellac like a hot knife in butter, and also will permeate the natural cork material!
This poses a severe problem for the restorer. It is not economically feasible to attempt to mass produce brass floats to replace the cork floats. Also, the company producing the poly-nitrofill foam floats has been most un-cooperative unless orders of very large magnitude are placed with them. We are currently machining float pontoons from this substance, to be used with the original float arm.
For those who are independently wealthy, individual brass floats can be made. This also may be a solution for a retired machinist with access to a good machine shop. This is a very time-intensive remedy, expensive if one must pay for the time.
For the rest of us, it becomes imperative to attempt to use a replacement cork (or foam) float, and seal the cork (or foam) against the permeation of the gasoline. The procedure we at The Carburetor Shop are currently using is as follows;
(A) Detach the original brass arm from the original cork float.
(B) Clean the arm (we use a glass beading machine)
(C) Attach the arm to the polynitraphyl pontoon included with this kit.
(D) Submerge the pontoon, and the portion of the arm in direct contact with the pontoon into a product called ‘POR-15’. This product is available from POR-15, Inc, P.O. Box 1235, Morristown, NJ 07962. They have a website at http://www.por15.com. READ THE DIRECTIONS. ACCORDING TO POR15, ONCE THEIR PRODUCT DRYS, YOU MUST WEAR OFF ANY YOU SPILL ON YOU! I BELIEVE IT!
(E) Remove the float from the liquid and slowly rotate to eliminate any bubbles.
(F) Suspend the float with a suitable hanger, and allow to air dry for 72 hours prior to use.
This procedure seems to be working with the current mixture of gasoline.
If anyone comes up with a better procedure, we would certainly wish to be informed!!!
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Appears to me that this float discussion is like oil/gas mixtures discussion: there will never be an end to it.
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