With the low rpm, air flow in the manifold is not smooth or
steady. A carb meters fuel based on volume and the engine
burns fuel by mass. Getting balanced and safe fuel mixture
in each cylinder with a carb is not easy, they tend to meter
a little extra at all power settings. Aircraft injection is
usually constant flow port injection, but it is more precise
and the fuel is dumped into the intake manifold just at the
intake valve. The automotive and newer aircraft systems
have controlled injectors which only squirt fuel as needed,
making even more accurate distribution.
Diesel and the big radial engines late in WWII/until the
1950's had direct injection into the combustion chamber.
[Most radials used a pressure carb [fuel injection with the
nozzle in the throttle body] or port injection.]


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.




"George Patterson" wrote in message
news:Volwf.18567$em5.10846@trnddc05...
| Stan Prevost wrote:
| "Jim Macklin"
wrote in message
| news:Wgcwf.40975$QW2.5751@dukeread08...
|
| point and then pull the mixture to shut it down. That
| should show a slight 25-50 rpm increase just as it shuts
| down since idle should be a little rich.
|
| For my TIO540-S1AD, Lycoming says five rpm, not more
than ten.
|
| The mixture on injected engines typically is not as rich
at idle as carburetted
| engines, so the rpm increase should not be as great.
|
| George Patterson
| Coffee is only a way of stealing time that should by
rights belong to
| your slightly older self.