QD16 10 hp Johnson

[sbump26]

This motor is new to me, but is a '55 model. I put carb kit in, changed impeller, and it starts good after setting low speed knob. Wouldn't go much faster than maybe half speed. I can move the rear butterfly by hand and the thing runs great. Set the high speed knob best as could (steering the boat, holding the butterfly open, and adjusting knob was interesting). I put the linkage for the butterfly and the arm that goes to the cam and roller back the same way it was before I took the carb. off. From the way it looks, it seems the linkage is too short. Would anyone with a serv. manual be able to tell me how long over all that linkage should be? Also, when I turn the throttle knob to wide open (not running,just working the throttle trying to figure it out), the cam roller runs out of cam and falls back under the timing plate. This seems like it would make the motor fall flat on its face. Is it supposed to do this? I don't have a serv. manual yet, but looks like I may need one. The motor runs great as long as I work the butterfly by hand. Would the linkage still be available? According to the parts manual I bought off of ebay the part number is 303539. The cam roller is also missing the top bushing and retainer, part numbers 303279 for bushing and 203363 for the retainer. I have found other things the previous owner did such as the knobs were backwards but the carb. was pretty clean considering the age and condition of the tank and fuel filter. I cleaned up the tank, put a tank to fuel pump gasket, replaced the filter, all the hoses. Runs and starts ok, just no WOT due to the linkage won't allow the throttle butterfly to open all the way. Could someone tell me if the linkage is available and if so, how long is it, and could the timing plate and cam be misaligned?

 

[rwise]

Re: QD16 10 hp Johnson

sbump26<br />sound like you need to do a "sync and link", you will need the manual to do it. Take a look at your local library, and copy the needed page/s. That will explain a lot. If there are missing parts they will need replaced of course. The cam should hit the roller at about 3/4 throtle and have the carb open all the way at full throtle<br />Richard

 

[Chinewalker]

Re: QD16 10 hp Johnson

Hi SBump26,<br /> There should be a lever on the starboard side (left when looking at front) of the motor that is actuated by the shift lever. This lever runs vertically and acts as a stop for the magneto plate. In neutral it should prevent the motor from being raced with no load. In forward, it should prevent the cam follower from running off the end of the advance cam. It's possible that after nearly 50 years some or all of these parts are worn, missing, etc.<br /><br /> Also, the advance cam is adjustable. One of the holes in the base should be elongated and allow for some adjustment....<br /><br />- Scott

 

[sbump26]

Re: QD16 10 hp Johnson

chinewalker, thanks for the post. The stops are functioning as they should. In fact, I had to make a piece to replace the one that was worn and allowing the magneto plate to go too far in neutral. I am confident that is working as it should. However with the throttle arm turned all the way open to WOT and the magneto base on the WOT stop, the cam roller falls off the cam. I will check to see if the cam can be relocated by adjusting the screws. The points look to be in good shape, so I am wondering if the previous owner replaced them and couldn't get it to run over half throttle (maybe less than that) and sold it. I haven't found out about if the linkage is too short or available, I am going to call the Johnson dealer tomorrow. It ran really well working the throttle by hand! It was very responsive, never faltered or hesitated, and the boat went on plane at about half throttle (12ft. alum. v bottom).

 

[Paul Moir]

Re: QD16 10 hp Johnson

While your fiddling with the cam, check the part number on it vs the one in your manual. I've never seen the part # printed on the brass stamped cams, but they are usually cast into the aluminum ones. <br />I'm thinking mabey he swapped the whole armature plate from a different motor.<br />Sounds like you have a bit of a puzzle on your hands.

 

[sbump26]

Re: QD16 10 hp Johnson

Paul that's possible I suppose, but it sure looks original. The bolts under the hood, around the block, and the magneto and stuff look like they haven't been taken off. The flywheel looks like it has been removed, there are scratches and indications that he used a puller that pulled from the edges. The bolts and screw holding the recoil starter on had been turned. The carb. bolts looked like they had been turned. The linkage to the throttle and cam follower was held on with some wire, and definately not original. The linkage looks a little suspect as well. The points look almost like new, the plugs looked new, the coil looks good, can't tell if it had been replaced though.

 

[Paul Moir]

Re: QD16 10 hp Johnson

Just out of curiosity, are the coils pinkish/reddish colour? I'd be really suprised if the engine still had it's original coils in it. I've never seen an original 50's - 60's ignition coil that wasn't falling to bits. Mabey it happens up here quicker.<br /><br />Anyway, I see your point about the roller end of things.

 

[sbump26]

Re: QD16 10 hp Johnson

Well moved the cam over to the starboard side and connected linkage. Now the roller doesn't fall back under the magneto plate, the roller lines up and makes contact where a scribed line is on the cam (which may be what it is there for) to line up the cam/roller interface. The only concern I have now is that in the WOT position the butterfly still won't be perfectly horizontal. There is still some movement left in the butterfly past what the cam opens it. Plus there is still about 2 inches of cam left. It looks like it goes this way, and will try it out on the water later. It is supposed to rain tonight and a couple of days after that. Will post results. Thanks for all the help and suggestions!

 

[Paul Moir]

Re: QD16 10 hp Johnson

That mark is so you can synchronize ignition timing with the opening of the carburator's butterfly. The adjustment is commonly called link & sync. I don't have a manual that covers the procedure for your year. The (later) QD-17 is adjusted so the butterfly on the carb *just* begins to move when the roller reaches this mark. Your QD-16 adjusment will be something like this, if not this exact adjustment.<br /><br />Sounds like you've got it set up right. Sometimes that last little bit of throttle butterfly opening makes no difference.

 

[sbump26]

Re: QD16 10 hp Johnson

Paul, Thanks for the information and encouragement. I will try the way it is set up now soon I hope. I think I am close to getting it right. The help and information that all the people supply on this board is incredible. Thanks to everyone who posts and replies to help a fellow boater and wannabe mechanic!

 

[sbump26]

Re: QD16 10 hp Johnson

Paul and everyone on iboats, I can't thank you enough for helping me get this motor running. I took it out today, and it runs perfect! Good low speed idle, from slow to WOT no hesistation, planes the 12 ft. alum. v bottom with 1/3 throttle with just me in it. Ran all over the lake today and had a blast. People were probably wondering what I was on, running around the lake with a big sh** eating grin pasted on the mug. Again, I can't tell you how appreciative I am of the help that I got from this board. It may be an old alum boat with an even older motor, but to me it is a yacht. The other boaters probably get a good chuckle when I take it out, but its mine, it runs great, and gets me where I want to go. I couldn't be happier. Thank all of you! Look out crappie!!<br /><br />Don Griffin