Spare and Ferm can answer the timing problem, but from where I sit I think that you're over-propped. Look at the differences in the RPM's. I don't know what Mercury recommends for WOT for your engines, but if they are both the same engine, then they should be turning (close to) the same RPM's at WOT. I would bet that your prop is either a 21 or 23 pitch. That would account for the better hole shot, and also the increased fuel burn.
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1987 V20 w/1987 150HP Yamaha on a Shoreland'r Trailer
1978 16.5 Airslot w/1996 120HP Force on a Four Winns trailer
1996 V21 w/1993 200HP Mercury on a Shoreline Trailer
All towed by a 5.7L Hemi Durango.
If God didn't have a purpose for us we wouldn't be here, so
Live simply, Love generously, Care deeply, Speak kindly.
(Leave the rest to God) 
Silence, in the face of evil, is itself evil. Not to speak is to speak, not to act is to act. God will not hold us guiltless.
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