Obsolete Outboards  

by Max Wawrzyniak - St Louis, Missouri - USA

Bringing a 1956 Johnson 15 hp Back to Life

Part VII: Gentlemen: start your engines

Part 1 - Part 2 - Part 3 - Part 4 - Part 5 - Part 6

With the carb and magneto installed on the engine, the carb throttle butterfly throttle valve "synchronized" to the magneto, and the points gap set, we are now ready to re-install the flywheel and "check for spark:" i.e. see if the spark plugs actually spark, indicating the all is well with the magneto (ignition) system.

Carefully set the flywheel down onto the crankshaft, making sure that the crankshaft "key" is seating fully in it's keyway (slot) in the flywheel, and that the flywheel is fully "down" on the tapered crankshaft- do not use any grease or oil on the crankshaft taper.

Slowly rotate the flywheel by hand (always clockwise, looking down on the flywheel) and feel for any "dragging" of the flywheel on the heels of the coil. The coil heels need to be very close to the inner circumference of the flywheel, but can not touch the flywheel. If You feel something scraping or dragging on the flywheel as you slowly rotate it, remove the flywheel and check to see that the coil heels are properly aligned with their mounting bossess as detailed in the discussion concerning setting the "air gap" in part #4 of this series.

Assuming that the flywheel rotates freely, I will "spin-on" the flywheel nut finger tight, and then "check for spark." One checks for spark by taking a spark plug, attaching it to the spark plug wire, "grounding" the outer metal casing of the spark plug to a good "ground" on the engine, and spinning the flywheel. Now, one can hold the sparkplug against a ground with one's hand, but be prepared for a pretty good shock assuming the magneto is working. It is an old mechanic's joke to ask the unsusupecting to hold the sparkplug against a ground. If the victim jumps and drops the sparkplug when the flywheel is spun, that is a sure sign that the magneto is working properly.

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A spark plug is clamped to a convenient bare-metal "ground" on the engine for testing the "spark." The spark plug is NOT touching the flywheel (poor angle on the photo)

My preference is to use locking pliers (Vice-Grips or similar) to clamp the spark plug against a good ground (preferably bare metal rather than painted) on the engine. With a spark plug wire attached to the plug, I will spin the flywheel either with a short length of rope, or even by just "flipping" the flywheel with the palms of my hands. If neither spark plug is installed in the cylinder head, there is little compression and the flywheel will spin very easily. Good practice would dictate that the dangling spark plug wire that is not being checked, should be grounded to the engine to ease the strain on it's coil, but I almost never bother with doing that and have yet to suffer for it (See illustration above).

If the ignition system is in good condition, I can easily spin the flywheel with my hands fast enough to get one or two sparks. You should hear an audible "snapping" noise and if the room is dark enough, you should see a small blue or white spark at the electrode end of the sparkplug. A yellow spark is a weak spark indicating a problem somwhere, such as dirty or improperly adjusted points, or a bad condenser. Since both cylinders have completely separate ignition systems, you will need to check both spark plug wires, not just one.

If you have a nice spark on both spark plug wires, you can now securely install the flywheel (I prefer not to torque it down until I am sure that I have the spark on both spark plug wires.) Re-install the flywheel nut/washer/ cover plates as they were when you first removed them (remember how I kept reminding you to take photos and notes?) and if at all possible, use a torque wrench to tighten the flywheel nut to the factory recommended specs. You will find flywheel nut torque specs along with other helpfull flywheel-installing tips way back in the old Magnetos column. If Chuckie is going to devote storage space for all those old columns, there really is no need to repost all of that stuff here as well.

If you don't get that flywheel installed correctly, this is what will happen.

Once the flywheel is torqued down, again rotate it slowly by hand and check for any dragging or interference with wires, etc. The spark plugs can be installed, although before doing so you might want to use your feller gauge to check to see if the gap between the electrodes is .030 inches. I am in the habit of installing new spark plugs out-of-the-box without bothering to check the gap and the engines almost always run well, but checking the sparkplug electrode gap is still a good idea. If the gap is not correct, just bend the over-hanging electrode a bit to correct it.

The last little bit of adjusting before we actually try to start this thing is to set the high- and low-speed needle valves to an intial setting for starting. If you have a service manual it will most likely recommend initial settings for these needle valves, but if you lack the proper manaul, I would suggest beginning with the high-speed (lower) needle valve opened about 3/4 of one rotation from the closed position, and with the low-speed (upper) needle valve opened about 1 1/2 rotations from the closed possition. As mentioned in part #5 one must be very careful not to tighten the needle valves against their seats as this can easily damaged the soft brass needles. We had left these needles about 1 full turn open but that may have been changed by the tightening of the packing nuts. Use extreme care to "bottom-out" these needles as gently as possible. If you have a service manual and the initial settings given are different than those given above, use your manual's settings.

You will need a tank of fresh gasoline/oil mixture. My opinion is that you can not go wrong mixing the oil and gasoline at a 16 to 1 ratio for OMC outboards up to about 1964, and 24 to 1 for post 1964 models. This is a bit richer than the factory recommended for some (but NOT all) models, but the potential for damage due to too much oil is about nil, while the potential for damage from too little oil is great. I always err to the side of caution, especially if the engine is to see hard use. I always use TCW-3 rated 2-cycle oil purchased at a large chain of discount stores founded by a guy named Sam, which is about the cheapest 2-cycle oil that I am aware of. I have never had an issue
with it.

We are now ready to try to start the engine. My preference is to try to start one in the privacy of my own driveway by utilizing my "outboard motor test tank" (plastic 55 gal. drum with the top cut off.) If you prefer to haul the boat and engine down to the launch ramp you can certainly try to start the motor with the boat afloat. I almost always run into some little problem that is easier to fix in the driveway with the tools handy so I prefer to attempt to start the engine there first (see Reviving a Vintage Big Twin - Part 3)

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If at all possible, make sure the water pump itself is submerged in water; not just the water intakes.

Since the plastic drum is a bit on the "wimpy" side, I usually mount the engine on one of my boats rather than attempting to clamp the outboard directly to the plastic drum. A 3 hp or maybe a 5 1/2 are about the biggest engines I will run clamped directly to the drum. A metal oil drum could probably handle a 15 hp engine clamped to it. Although you want to be sure that the lower unit is deep enough in the water to submerge the cooling water intakes, it is better to have it deep enough to submerge the actual pump (see illustration above). Having the actual pump submerged will prevent the impeller from running dry while trying to pick up the prime. It only takes a few seconds for an impeller running dry to be damaged, and I know of one mechanic who "pre-lubes" his impellers with KY Jelly, which apparently
does not harm them (insert your own joke here.) Keep in mind that some lubricants might harm the rubber impeller. My opinion is that if you submerge the engine to the extent that the pump cavity is flooded there is not need to worry about "pre-lubing."

Attach the fuel line and prime, using the primer pump on a pressure tank, or the squeeze bulb for a fuel pump-equiped engine, and check all your hoses and connections for fuel leaks.

Apply the choke, grasp the starting rope handle and gently pull until you feel the recoil starter engage the flywheel, and then give it a good steady pull. Do NOT grab the starter rope handle and jerk away at it; feel for the engagement and then a steady rapid pull.

Like the shampoo bottles say, "repeat as necessary."

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Running!! Note that the motor is actually clamped to the transom of the trailer-bound AF4 skiff, which makes a much more solid mounting than trying to clamp the engine directly to the wimpy plastic drum. Also note the colling water spraying from the exhaust relief hole halfway down the tower housing.

Hopefully, after a few pulls the engine will start up. It may be necessary for you to turn the choke on and off repeatedly until the engine warms up: if the engine is"coughing" back through the carb and "jerking" as if it was hitting something, most likely it is running lean. If it smooths-out with out 1/2 choke, then you need to open the needle valves just a bit more, no more than about 1/8 of a turn without allowing a few seconds for the engine to get used to the new setting.

If the engine is really smoking, it might be getting too much fuel; make sure the choke is off and you might try closing the needle valves just a tad, again no more than 1/8 of a turn at a time.

Odds are you will accidently kill the engine at some point when you guess wrong what it needs (more gas or less gas??). Just keep playing with it.

If the thing doesn't start at all, have you flooded it? Remove the spark plugs- are they wet with gasoline? If so, allow the eninge to sit for a few minutes so that the gasoline can evaporate, then re-install the spark plugs and try starting again but use less choke this time. if you pull the spark plugs and they are completely dry, try using more choke or maybe opening up the needle valves 1/8 of a turn each.

This can be a frustrating activity for the newbie, but keep in mind that your engine ran well at some point in the past, and if you did your work carefully (and there is no damage that you overlooked- it does happen) then it should run well again.

Once the engine has been running in a test tank, THEN I will haul the boat down to the launch ramp for an on-water test. Be advised that an engine that appears to run OK in the tank may not necessarily run properly on a boat, so don't load-up the family and a picinic lunch for an afternoon of boating until you have succesfully tested the motor on the boat in the water. You will certainly have to "fine tune" the needle valve adjustments. The proper procedure is to warm up the engine on the boat, and then head out at full throttle, slowing adjusting thje high-speed needle until you get the most speed. Then slow down and adjust the low- speed needle to give you the best idle.

What went wrong with the first starting of the 1956 15? Well it started-up OK, but refused to pump cooling water. I removed and re-installed the lower unit and then all was fine so I just assume that I failed to get the water tube seated in the grommet (seal) on top of the water pump housing. As mentioned in part #2 re-installing the lower unit can occasionally try your patience. Take your time and don't get in a hurry and remember that it took me (2) tries to get the thing working properly.

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The '56 15 with a coat of primer. Prep, primer & paint will be covered in future columns when it's bit warmer in the shop than it is right now.

The plans are to repaint this engine as "nicely" as possible without spending a lot of money on it, and without making it look so "nice" that I am scared to use it for fear of scratching it. But winter is now upon us and my unheated shop is currently full of antique aluminum boat and half-built kayak, so the paint job will probably wait until spring unless I get some decent breaks in the weather. So the next few columns will deal with other subjects and then eventually we'll get back to the 15.

Happy Motor'n

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