Just acquired a nice original brass carburetor for my 1917 Maxwell. The float looks perfect and appears to NOT have any type coating just very tight grained natural cork. Do I HAVE to seal it or can I run it as is?
Thanks for any help or suggestions,
I seal mine with "Hot Fuel Proof Dope" from a Hobby store that deals with Remote control airplanes. Cork won't last long other wise.
Shellac is what was used in the old days.
HOWEVER - while it doesn't dissolve in gasoline, it does dissolve in alcohol so it won't suffice unless you use only non-oxy gasoline,
Do like Kenny says; fuel proof airplane dope is the way to go. About three coats does the trick. I just pulled an old cork float out of 1949 Mercury 5hp outboard that had shrunk up to a quarter it's original size thanks to fuel erosion.
I sealed the cork float in my Marvel carb with alcohol proof gas tank sealer. So far so good.
Interesting, same discussion going on, AACA forums.
Cork is a closed cell wood, very different from other species.
A proper, real, cork, will last for years and years in gasoline, absorbing very little. No coating is necessary.
Yes, this goes against our perception of wood, but it's the real science of the matter.
Cork is still a plant fiber, plant fiber WILL absorb gas, does not matter if it's closed cell or not. Every book I have seen even from back in the day says to coat the cork to prevent it from getting fuel logged. Water and gas are not the same.
I have personal experience with a cork float absorbing gasoline to the point it became 'water logged' and no longer shut the fuel off like it was supposed to. This was in an antique outboard motor. I fixed it by coating with tank sealer and it is working to this day. Closed cell or not, my real world experience is that they do indeed absorb gasoline and fail to shut off the fuel supply reliably.
Funny how reacting without All the facts can bite you in the butt! I took the top off the carb and started asking questions on what I saw. This morning after all the discussions I decided to remove the float and I found it was shellaced years ago which has all dried up and cracked so I guess I'll see if I can dissolve the shellac and recoat it.