Re: Dockbuster Question
Actually the direct reversing motor has but only one distributor. There is special linkage which lets the distributor rotate far enough to allow the engine to be started/run in reverse. Since this type of 2-stroke doesn't care which way it runs, the engineers at Mercury very cleverly figured out how to get the timing reversed with just a pull of the single-lever control.
The "Dockbuster", however, does have 2 sets of points, and each set runs 3 cylinders. 1-3-5 fire off the first set, and 2-4-6 off the 2nd.
There are 2 coils as well. So basically you have 2 completely independent ignition systems firing the motor. Needless to say, the timing between the 2 sets of points has to be spot-on, or else the firing pulses on even and odd cylinders won't be in synch. This can cause vibration, poor running, and even a busted crankshaft!
Note that the Full Gear Shift Inline Sixes had a similar ignition system (until they went to electronic ign in the mid-late 60's), but the FGS models didn't have the reversing capabilities.
Another special feature of the Direct Reversing engines is the bi-directional starter, with one gear on top and the other on the bottom, engaging their respective Fwd or Reverse directions. A set of limit switches (in the engine for early models, and in the control box for later models) keep the starter solenoids deenergized, if the throttle setting is too high.
So, all in all you have a very special motor, with a lot of adjustments to make! But when everything is spot-on, they'll start and run like a champ.
Back in the 80's I picked up a Merc 700E Dockbuster for $25 off the shop bulletin board. All I had to do to get it back in service was fix the busted pump housing with some J-B weld (!) and clean/set the points.
Threw 'er on my brother's 13-1/2' Sea-King runabout and we ran the tar out of that motor the entire summer. My good buddy liked to beach-start slalom-ski, so we made sure there were plenty of coils on the ski rope, when he said "Hit it" I'd start 'er up and away he went! He said the acceleration made his head swim! It would easily deep-water-start a slalom skier and topped out around 35 mph. I've had a lot of nicer/faster boats since then, but few of them have been as fun as that Economy Special! Certainly none were as cheap. Hard to find those $25 motors nowadays!
If you've got one that's tuned correctly, she'll go from idling in fwd gear to full stop to starting in reverse with no trouble at all. Mine would fire right up with the tap of a key.
The direct reversing gearcase has less parasitic drag inside of it (less gears to sling oil around), so you're actually putting more power to the water than a similar FGS model.
For their time, they were quite the deal. I fully second what Willyclay said, owning one is an excellent experience and you'll learn a lot working on it. Not for the faint of heart, though!
Cheers..........ed
