Tex, you just described the decal on your 85 merc as being a 76-77 vintage, just like the one in the pic above
OUTSTANDING!!!!!!!!! Nice and shiny like mine was too, course I bought mine new and kept it garaged, should have been shiny. For your's to look like that today is remarkable. I'll try to remember the year model. I bought the Caravelle new in '72 and the family lost interest in boating. I liked to fish and wanted a fishing boat so I sold the Caravelle and bought this. Didn't realize I sold it so soon; thought it was 7 years old when sold, but that's pretty close.
That was the finest engine I ever owned with the Johnson a close second or maybe vice-versa....never had a minutes trouble with it. Had zero problems with it either and it was a walk in the park to start and run. I used to fish a lot in the winter around Dallas and I could launch that sucker and be on my way in a matter of minutes while a lot of other guys were fiddling with their engines trying to get them to start.
The air box on it and the 4 cylinders running at WOT made some beautiful music. That was my first engine with the air box (the plastic box covering the carburetors).
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I think the Canadian's picture nailed the potential problem and may be the reason why a shallower pitch would be right on that rig. First of all there is a lot of stuff in the boat as compared to the boats used back when I was boating. Second the hull looks like about a 20 or so degree dead rise and some other disturbances in the stern. If there are stern seats in front of that splash well, bet they are usually occupied and that adds to the problem, even unoccupied, weight in the stern is weight in the stern. Hulls like that ride beautifully (soft), even in a tri hull, (sponsons catch waves especially when quartering into the wind) but it comes with a price. Deep Vs require more HP to get up (dogs in the hole shot) and on the water and don't really plane out like a flat transom semi V. Course that's why they are smooth riding. A semi V rides on top of the water not in it like that boat and as a result in rough water they just bounce from wave crest to wave crest.....but they are fast hole shooters and run faster on less power. At my age the deep V IS the hull of choice.
Fazt.....can't argue with you when you were there and saw it, but couldn't it have been caused by something else/ Did the prop get swapped out in the same type and ratio as the gear ratio changed? If so then the dog had to be associated with prop slip and was worse. Was everything associated with the boat the same, same trim position, and all that??????? So my next question (gee I'm full of questions) is, why did a change of 15% in a gear train, matched to a countered 15% change in prop pitch cause the prop slip to change to the point of making a dog out of the rig?