Okay, this confuses me so I may not be able to relate it in a non-confusing
manner.

Twin engine 5.7l alphas, starboard tach is new and a different model than
the port tach (which is OEM, 14 years old).

Here's the deal. When I have the engines synched up according to the synch
gauge the starboard tach shows about 200-250 rpm less. The starboard control
is also "behind" the port control, indicating less throttle.

If I balance the tachs, ignoring the synch gauge, I can't "hear" any better
or worse synch in the engines -- as you may recall I'm a new boater. However
the controls are more closely aligned.

But by sound or feel alone I can't tell if the synch gauge is out or the
tachs.

During acceleration or decelleration sometimes I get them way out of synch
and I've never noticed any vibration or anything that you guys have
mentioned about out of synch engines other than hearing an rpm difference. I
don't think I have enough experience to hear it down to a few hundred RPM
though.

This weekend I ran at WOT for a few minutes. I had the port throttle all the
way open but the starboard one still had some room to move - a fair amount
actually. I didn't move it all the way open because I was already reading
well out of synch and didn't want to booger anything up.

I believe I have some separate problems here so I'll lay out what I would
"like" to happen.

1) Quite simply, I would like my tachs to tell me what actual RPM my engines
are spinning. I learned from a previous post that there is a "time
reference" issue involved with tachs and perhaps some other voodoo but let
me say this about that, I just want to know *accurately* what the friggin'
RPM is. Am I asking too much here? Is it not possible to get an accurate RPM
reading?

2) If I can do #1, then I can easily figure out if my synch gauge is
boogered.

3) This is the separate part I think -- is it normal to still have some
travel left on one control while the other is wide open?

Thanks in advance for any insights you may be able to provide.

Needless to say, full throttle should cause the engines to be *at*
full throttle.

Hmm, good point. I assume that with the engines off and engine hatches off I
could advance the throttles all the way and check to make sure that the
actual throttle levers on the engines are right up against their stops? Any
reason this would be a bad idea? Might flood the carbs but that's easy
enough to deal with.

You could also swap
the tach wires and see if the problem changes from one engine to the
other, thus determining if it is a tach problem or an engine(throttle)
problem.

Oh my God what a simple idea ... geez. Just switch my starboard tach over to
the port engine and if it gains the missing 250 rpm (or not) then I've got
my answer. With my luck it will read just different enough to inspire more
questions.

Thanks, that gave me a couple of avenues to try.