"Ben Jackson" wrote in message
news:aJ8Fb.103545$8y1.318631@attbi_s52...
| 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.
|

That's right, he is talking about a Piper, there.