Hi, my OS7H (1980's vintage) midrange/idle "needle" o-rings are leaking. After two tanks of fuel hovering yesterday, I am getting foamy fuel from the seals, and engine quitting at mid-range.

Is there a way to swell the old o-rings? Automotive Brake Fluid?

Any suggestions appreciated. Thanks!

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Acetone will do it , or so I am told by my clubs resident industrial chemist . You could just add a couple of percent to your fuel , I have been advised that even diluted to this extent it will still cause the seals to swell . I found out because I had asked with the intension of trying a small percentage of acetone because of certain benefits that it is supposed to have , but as it is likely to swell the "O" rings I decided against it .

Or you could get really radical and fit new rings .

At the end of the day , it gets dark .

Automotive Paint thinner worked

I had some nasty automotive paint thinner, a few minutes of soaking and the rings swelled nicely to form a great seal again. Thanks!

Are new O-rings still available for your engine. Many "swelling tricks" are short lived.

If God had meant for man to fly, he would have given him more money

yes it wont last long. they usually go back once the thinner is evaporated. I cant imagine you cant get new O rings for it.

[b]heli flyer by day, custom making cnc heli parts by night[/b]

The only thing that I can think of for that carb is to jack it up and slide a good carb like a Supertigre underneath it.

They sucked back then and if the o-rings aren't copacetic now it will really suck.

TM