Bob Chilcoat wrote:
Friday, one of my partners and I changed the oil. Afterwards, we took it up
for a spin to reward ourselves. As I rotated, I glanced down at the tach
and was rather horrified. Redline on the Archer is 2,700 RPM. We were
turning 3,300! 600 RPM over redline. Huh?! Since we still had the full
length of both prop blades, the only logical explanations are either that
someone put a different prop on in the dead of night, or that someone
sneaked up and hopped up the Lycoming. We have to be getting 240 hp to see
that much overreving on climbout. Wow. Thanks, phantom tuner. What a nice
guy...

Oh crap! The rate of climb isn't any different.

We've ordered a new tach.

--
Bob (Chief Pilot, White Knuckle Airways)

There are two different kinds of tach pick-ups for instruments. One is
direct drive from engine to tach by a cable the other is electronic
pick-up. If the engine sounds were the same I would think you have an
indication problem. Have your local A&P use a calibrated RPM gauge and
check you RPM this is the first test.

It may be a bad cable, faulty electronic pick up or just a bad tach.
You're A&P should know in short time what the problem is. Regardless
have it fixed before the next flight.

Stache