I've never seen one leak at the O ring. Are you sure it's not leaking at the vent from an improperly set float?

I had a similar issue with the Tecumseh on my snowthrower. I think the float was seated incorrectly. I did change the O ring too...came with the new float.

A speck of dust in the seat will do it too. If you change the seat, make sure the smooth side is visible after its installed.

I have done all of the above, new bowl, checked float level, reversed the direction of the spring like thing that holds the needle ( manual says, loose end should be facing the air intake) I've had it apart 5 times and still leaks. If it was cooler I'd take it apart again but I'm going to wait for a cooler time. Any other majic potions?
Mike

Did you change the seat? If the needle is seated, gas can't come in and it will never get that high in the bowl unless you are angling it too much on that bank. Is there gas inside the float itself?

Was: Visually inspect the Float Ball itself perhaps it has seen better days . Quite often the silver solder seam begins to leak and the float does not become sufficiently boyant to close the fuel supply needle valve therefore the fuel continues to seep in and out the vent on the Carb Body .

Thanks to all the replied. I replaced the wronf seal the 1st time I tried it. Replaced the needle seat an all appears to be well.

Thanks for the help
Mike