To All:

Of the two methods of absorbing heat (ie, acceleration of the air &
change-of-state for the gasoline) the endotherm resulting from the
vaporization of the gasoline can be as much as 100 times colder than
the venturi-effect.

As for the amount of water in the atmosphere, we know there is ALWAYS
some... at least, on this particular planet. The FAA provides a chart
that allows you to figure out your probable icing point.

What gets people in trouble is the assumption that the ambient air
temperature plays a SIGNIFICANT role in carb icing. Not so -- at
least not with regard to the 'significant' business. Indeed, when you
have a nice WARM day you are more likely to develop carb or manifold
icing than on a nice COLD day.

Personally, rather than try to figure out the humidity, freezing point
and so forth, I assume icing IS probable and shuffle the knobs
accordingly. Works for me.

As for heat muffs, the FAA expects ours to provide a 90F rise in the
inlet temp to the carb. Truth is, most muffs don't come anywhere near
that amount due to a lack of heat in the exhaust stacks OR
insufficient surface area for the heat to transfer two. Annd if
you've done like most of us and wrapped an over-stretched screen-door
spring around the exhaust stack, odds are it rusted itself into FOD
during the Eisenhower administration. What you wanna do is getta
pound of .035 safety wire and wind it into a coil around a piece of
rod and use that instead of your door spring. OR get yourself about
four of those stainless steel pot-scrubbers and use that. OR get
yourself about fifty feet of .010 stainless steel 'razor blade stock;'
about 1" wide and bend that into angle stock and wrap that around AT
LEALST TWO of your exhaust stacks, because the SIGHNIFICANT factors in
the equation are surface are surface area and thermal flow, so that
while the Choir Girl pads are hands-down winners for surface area they
screw the pooch when it comes to thermal transfer AND cause too much
restriction to begin with.

So give the razor-blade stock a try. Snip it four or five times per
revolution and give each resulting fin a bit of a twist... then go
back and crimp each of the 'fins' with a pair of fluting pliers so the
fin ends up sorta wavy.

Nothing here is carved in stone but a weekend experimenting with a
lawn-mower engine and an IR temperature sensor is equal to a couple of
months sitting in a classroom.

-R.S.Hoover