Ben Jackson wrote:
In article ,
C J Campbell wrote:

The tach should almost always run slower than the Hobbs. The Hobbs is a
clock, but the tach is connected directly to the engine and should only
click off one tach hour when the engine has turned 60 x max rpm.


But it's not "max rpm". In my Comanche (260hp IO-540, redline 2700RPM)
it's 1:1 at 2300RPM. I think the "definition" of tach time is 1:1 at
cruise.


I guess this is the question I'm asking. Where does 1:1 occur. On the
particular trip I was running 65% which at that altitude was 2425 RPM.

John Roncallo