<VV> Jets for power

[NicolCS at aol.com]

12.5 - 13.5 air fuel ratio = max power
14.8 = "ideal" ratio "stoichiometric" where there's an exact match of oxygen 
molecules to fuel molecules.  Catalytic converters like this one
15.5 -16 max fuel economy in a conventional engine

Carburetors can be tuned to any two of the above.  For anyone who isn't 
running a cat, 13.5 and about 15 are common targets.  If you haven't installed an 
AFR gauge, you are just guessing where you are.

I don't believe that rich mixtures make the engine to run cooler - but they 
do bring up the bottom as far as lean pockets in a poor head design is 
concerned.  If you have to detune (retard spark) to keep these lean pockets happy (no 
detonation), that retarding of the spark will cause the engine to run hotter.  
AFIK, burning less fuel for a given condition creates less waste heat that 
has  to be taken away by the cooling system and exhaust. I must have had 20 
people tell me that EFI wouldn't work in a Corvair for a variety of reasons; 
mostly that "them fuel injection systems run too lean, Corvairs need a rich mixture 
to stay cool".   My 66 runs at 275 on the freeway on a hot day. So much for 
that "theory".  Airplanes take off at "full rich" because that's where they 
make the most power. Once aloft, pilots lean out the mixture for good fuel 
economy and engine cooling.
Craig Nicol
<snip>I always thought that not fuel gave you more power, within reason. 
Someone  
told me tonight that leaner is better for power and more fuel will result in  
less power but less chance to damage the engine. Airplanes set "full rich" 
for  
takeoff and climb to get the most power out of the engine. The mixture is 
pulled  back, leaned out, in cruise for economy. <Ned>