I have a 69 merc 650 brought back from the dead. It starts instantly, runs very smooth with no unhappy noises shifts well. compression 120# x4 cyl nothing leaking. We have it on a 16 ft 58 mirrocraft shallow v closed bow aluminum runabout. The boat has an added wooden floor which adds a bit of weight but not tons. The best we get out of this is 23 -24 mph. (With a mercury 402 40 hp we get 20 mph) It takes a long time for it to wind up to top speed.
This motor has the "lightning energizer" ignition. As best as I can tell from the clymer manual it seems to be timed right and the throttle is against the stops at WOT. however, this exact configuration does not seem to be in the clymer manual my mercury dealer sold me.
I do not trust the tach but it says about 5k RPM WOT
I feel it reads high by the sound of the motor.
prop is 3 blade 13 3/4 by 17 pitch. Is this over propped or could something else be wrong? I was thinking of a 13 X 15 prop.
I also have an old 2 blade merc prop that is a 15 pitch that was on an other old 650 but it needs a repair.
Any thoughts? I thought I might be able to get 25 -30- mph out of this thing.
Thanks much for any wisdom you may share
This motor has the "lightning energizer" ignition. As best as I can tell from the clymer manual it seems to be timed right and the throttle is against the stops at WOT. however, this exact configuration does not seem to be in the clymer manual my mercury dealer sold me.
I do not trust the tach but it says about 5k RPM WOT
I feel it reads high by the sound of the motor.
prop is 3 blade 13 3/4 by 17 pitch. Is this over propped or could something else be wrong? I was thinking of a 13 X 15 prop.
I also have an old 2 blade merc prop that is a 15 pitch that was on an other old 650 but it needs a repair.
Any thoughts? I thought I might be able to get 25 -30- mph out of this thing.
Thanks much for any wisdom you may share