> Dave,
    > Having had to deal with many carbs and FI systems over the years I
    > would
    > respectfully disagree that carbs are safer. While there is higher
    > pressuure fuel in a FI there are systems designed (hoses and ends) to
    > deal with it. The float valve in any typical carb is the weak
   link. The
    > fact that the gas is pumped in by "only" 6 PSI is little comfort
   when
    > you
    > have an engine fire. In fact if turned off the FI system provides
   less
    > to burn. (No float bowl)
    > Bill Jepson


   Hi Bill,
   I see your point but the reasoning was more as follows:
   A leaking hose in FI produces a fine mist which, if ignited, makes the
   cowl a bomb.
   A carb leak will more likely produce a fire, so turn off the fuel and
   remove the source.
   Of course, these are only likely scenarios; the carb leak because of a
   stuck float valve could also lead to an explosion; but the high
   pressure mist in the FI example is almost guaranteed to explode. It was
   more that the explosion was the worry rather than the fire.

   We have a couple of old bike racers in our club  and we spoke at length
   on this possibility and the general opinion was that float valves
   rarely stuck, and when they did, often the valve stuck in the closed
   position; cutting off the fuel. Also the Bing and Mikuni 'caged' valves
   are much more reliable than the old Amal "free" valves.

   Further to this debate, in your bike days, how common was a stuck float
   valve and in what position?

   Thanks for your valued comments, BR, Dave McC

Dave,
Older bikes are a bit of a different subject since gravity feed was
normally used. We saw both stuck open and stuck closed, the latter
mostly on machines that had been inactive. With fuel pumps, and that is
very common now, stuck open is more common. Usually stuck open float
valves being caused by debris. Running a good filter reduces this greatly.
With respect to the under cowl mist being sure to cause an explosion I
must say bunk, sorry. Few cars built any time in the last decade have
had carbs, all are fuel injection. You don't see sudden fire balls on
the road. It would be just as likely as with an aircraft with many cars
having extraordinary under hood temps. Hell if it was common the
resultant lawsuits would be all over the papers. Additionally the number
of leaking and ill-maintained cars would make ANY comparison to planes
look like a tiny sample of generally pampered engines. On racing engines
I would say I have seen far more mechanical failures than fuel failures.
Put more simply, I would say if you are more comfortable with carbs
RUN THEM. You should remember though that more aircraft accidents are
attributable to carburator icing than any kind of fires. FI engines
don't have a problem with icing. I had the carb on my 172 ice up once on
a night flight into Montery, scared the crap out of me honestly. I was
getting ready to let down for landing and the normal "carb heat on for
decent" proceedure saved the rookie from further misfortune.
Bill Jepson

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