Reporting back.... all the info you guys provided is pretty much spot on. I had to satisfy myself and the what ifs... that push thinking people on their quests for knowledge. Thanks to all for bearing with me.
I spoke to Merc they were surprisingly helpful but could not or would not provide the advance curve details (TA). He did say it will only advance to a specified point and stop at that, which is not what I discovered when I connected a timing light.
I checked base at 10, then disconnected the ground wire and increased RPM's in 500 RPM increments..
1500 ~ 20 degrees
2000 ~ 26/27 degrees
2500 ~ 30/35 degrees
3000 ~ 37/42 degrees
This was while under way.
Needless to say I left it at base 10 and it may be slightly above 10, but it idles and shifts fine.
I only checked the original module, I purchased a spare module I bought form a dealer at 1/2 price, it was NOS so it was not the conversions kit, which is ok because I can keep one as a spare and change by unplugging old and plugging in new. Part of the concern was the confusing part number on the replacement. According to my research it was for a ALPHA L , 2 bbl carb....?. I have a LX with a 4 bbl. However the replacement conversion kit part is the same for both the L and the LX.
Is it possible that mecr could have made this any more confusing?
I used a Snap-off timing light that allows one to look at 0 degrees and dial it ti read the actual BTDC timing.
Concerning my numbers, the first number is the degrees it held relatively steady and the second number is a approximate of where and how far it was "bouncing".
I am done boating for the year, I will look at my spare module next season and see it if compares.
I am happy with the TB-V and how it works, my fuel mileage was very good on this last trip, I logged about 170 miles and ~ 2.3 MPG, 7000 pound outfit and cruising 25-28 MPH typically at 3350 RPM, which seems to be the sweet spot for this motor/boat.
It was clam seas and good conditions on this trip, big difference from before with 4-6 foot seas and running 15 MPH and 1.9 avg MPG.
All for now, Thanks all......!
PS, its not about economy, its about endurance and how far you can go on a tank, yes I know the rule of thirds....
