[TR] SU carb fuel bowl

Randall tr3driver at ca.rr.com
Mon Jun 4 11:52:49 MDT 2012


> Everyone shudders at the thought of gas dripping on a
> manifold, but my understanding was that, unless there was a source of
> ignition, the gas would not burn.

I suspect it depends on the particulars.  I have seen gas dripping onto a
manifold that was literally glowing red (it turned dark after every drop
then got red again) and it did not ignite.  I have also seen people put out
a burning cigarette in liquid gasoline (as a stunt of course).

My guess is that the distinction is because gasoline will only ignite when
mixed with air in a fairly specific ratio and simultaneously heated above
230C.  With a clean, bare manifold, the gasoline evaporates and thins out
before it gets hot enough to burn.  But if there is any kind of material
present to absorb the gasoline and act like a wick, it will burn.

BTW, the trick to putting out a cigarette in gasoline is to do it fast, tip
first, so the fire is quenched before the gasoline penetrates the cigarette.
If you move too slow or let it go sideways, you'll get burned.  Likely you
also need a well-ventilated area (so there isn't a layer of flammable vapor
lying on top).

Don't try this at home <G>

-- Randall 


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