"Name That Outboard"

[Mark75H]

Many of the four stroke outboards and the two stroke snowmobile applications use duel coil wires with one trigger input. The plug will fire at TDC and BDC.

Onan's old stone age CCK series generators (I think starting in the 40's or 50's) did the same thing in 4 stroke mode; both plugs fire both times, but it doesn't matter to the one with both valves open

[Roy Hodges]

[QUOTE=Tomtall;68652]Many of the four stroke outboards and the two stroke snowmobile applications use duel coil wires with one trigger input. The plug will fire at TDC and BDC.
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It seems to me that it started with the Honda 125&150 CC 4stroke ( twins ) motorcycles ,back in 1960 . Both cylinders fired only 180 deg. apart ,then skip a whole rev. before firing again . Horsepower rating at 10,500 rpm -plain jane stock, street models ,out of box

[Tim Kurcz]

For all,

From my former outboard mechanic life, I recognize that wild powerhead can be anything from the 22 cubic inch 20-25HP to the 32 cubic inch 30-35HP - both deflector piston engines. If building a wild mod like this, I'd sure build it to meet class rules (FE) while using the biggest displacement available.

The dual plug head is very cool as it makes for faster light off with a backup in case of a foul or coil failure. BTW: Rapair seems to think two coils can be placed in parallel and that there's enough energy to run both. Looks like a good project for one of my 49.9 triples..... Watch out boys!

What I find most interesting is the decision to use enclosed exhaust. Personal experience with the local marine sheriff finally led me that direction. This is one of the reasons my kids don't like the hydro: They always associate running the hydro with a not-to-happy visit from the DNR and or Sheriff! Just last year I built my first quiet triple with wonderful results - no noise complaints! So, I can test my triple just like the 45SS.

A side benefit is you can't copy what you can't see. Roger Dykehouse used this technique very effectively with his "bounce can" B-Hot Rod deflector exhaust system back in the 1960's. He was shocked at the additional power made by this system (I have to original in my possession). My guess is he stumbled upon what you might call a folded expansion chamber. A quiet system, his engine went on to win at least 3 national championships before a set of sliding chambers overtook him. My guess is this type of technology is/was used in such engines as the Merc25XS, OMC A-15 and 45SS. All are very quiet and make tremendous power.

One thing for sure, I'd love to see the port scheme for that monster!

Tim

[Sam La Banco]

Tim, your right about the Dykehouse can, it does work like the folded systems found in a modern production motors midsection.

But if you think the Ign. was trick on this motor, the side carb setup was really cool. I wonder if anybody can figure it out.

We tried this motor on a borrowed hydro intended for a yamato 80 motor, what a ride, not even close to enough boat. There is an old picture around maybe I can find it, you will see what I mean.

[RogerH]

This motor is definitely intriguing! Tim, I read with interest your BTW: that Rapair felt there was plenty of power to fire two coils in parallel. I believe that is how the dual OMC coils were wired when I received the motor. My concern was about associated with the charge current to fire both coils at the same time.
On the 2-cylinder motor I'm wondering what kind of a trigger was used to have a lead available for each coil. If there are two pick-ups (per cylinder) they could be offset slightly to give a longer spark pulse duration across both plugs for better burn. Much like MSD does with multiple sparks (under 3000 rpm), but this wouldn't be RPM limited, only saturation limited if the charge current dropped off as RPM increased.
This motor has a lot of things going for it in one package. I anxious to hear what it really contains.

[Tim Kurcz]

Hi there Roger,

From what I've been told, the factory OMC primary will fire two coils, so it seems paired pickups would not be needed. This engine has given me several good ideas based on external inspection. The exhaust, ignition, and the very interesting side mount carburetor. Seems to me there could be a reed box behind it, or perhaps it simply opens into the bypass cavity. If that were the case, it wouldn't be opened until larger throttle openings where it might allow better crankcase filling after primary breathing is done by the front 2-bbl.

BTW The V-6 Johnson you have is a very cool race engine! I'd sure do the research to find coils for the twin plugs.

Tim

[John Schubert T*A*R*T]

Tim, your right about the Dykehouse can, it does work like the folded systems found in a modern production motors midsection.

But if you think the Ign. was trick on this motor, the side carb setup was really cool. I wonder if anybody can figure it out.

We tried this motor on a borrowed hydro intended for a yamato 80 motor, what a ride, not even close to enough boat. There is an old picture around maybe I can find it, you will see what I mean.

Sam,

Is this a continuing project of the 25 that Dave Hammond might have started?

[Sam La Banco]

John
This is the engine that Dave configured back in the early eighties, as far as I know, it's the same as it was back then, it made 50Hp on dyno. If Dave continued to develop it, I'm sure, with what he knows it would end up more.

Just think what he could have done with the "45" and the "A" motor when we did those projects (if OMC let us.)
He did a "pretty trick" mod 50 motor too.

Tim, there are no reeds behind the side carb, it's piston ported.

[Tim Kurcz]

Hey Sam,

Of course! Thanks for solving the riddle. My experience with piston ports dates to the 1970's and Bombardier snowmobile engines (hows that for Evinrude destiny). Simple and effective, the only downside I remember was a jumpsuit covered with spitback! With no reeds to get in the way, crankcase fill must have approached 100%. There's no doubt this contributed heavily toward the 50HP. What great work, and to think this was done almost 30 years ago! It would be fun to see it run again.

Tim

[calvin]

Was this motor used in FE or 25ss? Is that a 2barel from a 50 or a v-4?...What make is the side carb..looks like a carter n?