'85 Sceptre, project planning

[Bushwacker]

Maybe some current owners can confirm this, but the later model non-Potter Sceptre's have a reputation for being somewhat bow heavy, evidently because SeaCraft Industries used plywood instead of balsa core in the decks and cap, plus the fiberglass seat boxes also add some weight forward. Some folks doing restorations on them have reported finding pig iron weights under the deck in the stern, evidently put there as ballast to compensate for the bow-heavy condition. (You might be able to check for the presence of those weights by moving a hand held compass over the area to see if it's affected by the iron.)

Bottom line is that I don't think you need to worry about moving batteries forward. The boat would probably even tolerate a heavy 4-stroke motor mounted on a bracket with no adverse effects, although if it did prove stern heavy in that configuration, you would have the option of pulling up the deck to remove the ballast weights.

One comment regarding the twin 140 motors . . . my understanding of how OMC got 140 hp out of what used to be a 135 hp powerhead is that they moved the top rings closer to the top of the piston. (This has a slight effect on when the intake and exhaust ports open and close, similar to changing the cam timing on a 4-stroke motor.) The net result is that, due to the thinner ring lands at the top of the piston, they are a bit less tolerant to detonation, so it's real important to NOT run low octane fuel in those motors! If they have good compression, I'd try to run at least 90 octane non-ethanol fuel if possible. You could also run 92-93 octane premium E10 gas, but with the E10 gas, if you happen to get enough water in it to combine with all the ethanol, it will separate out and drop the octane level by 3-4 points, which can be fatal to a 2-stroke! Since there are no valves to rattle, you can't tell if you have detonation in a 2-stroke until it either destroys the rings or blows a hole in a piston!