1984 Johnson 35hp Throttle/Carb/Timing sync

[Boomhauer]

Long story short, picked up a Tracker Guide V14 with a 1984 Johnson 35hp 2 cylinder 2-stroke tiller (J35RLCRR). The low speed needle retaining ring had disintegrated, so while I was replacing that I went ahead and removed/cleaned/rebuilt the carb. Now I have everything back together and am trying to get everything synced/adjusted properly.

I am referencing the OMC manual as well as Seloc manual 1302.

I am trying to set the "Throttle Pickup Adjustment" and "Throttle Control Rod Adjustment" according to the OMC manual. However, these settings seem to contradict each other. I really feel like I am missing something or misinterpreting the instructions. I am using the throttle control rod set screw/nylon block to make my adjustments. The manual states to use the adjusting screw on the lever where the throttle connects to the carb. That makes sense if the follower is not contacting the cam, but I don't see how that would affect lining up the cam follower with the marks as the carb begins to open.


Scenario 1, Throttle Pickup Adjustment
[1] I adjust the throttle control rod such that the carb begins to open just as the cam follower is between the two marks on the spark advance cam (this seems most important)

Since the throttle lever is not contacting the engine block when the carb reaches WOT, the carb continues to try to open past WOT and causes binding. Does the throttle lever need to rotate all the way to the engine block to advance WOT timing properly?

Cam follower leaves cam right between these marks as carb valve begins to open, and contacts the cam between the marks as it returns to the cam.


Throttle lever still has room to move before contacting engine block, so the butterfly valve tries to go past WOT in the carb. This makes me think spark advance is not fully extended at WOT, and I am putting undue stress on carb throttle linkage.



Scenario 2, Throttle Control Rod Adjustment
[1] Advance throttle lever to stop against the engine block by hand (engine in forward gear)
[2] Manually open carb throttle valve to wide-open position (blade perfectly horizontal)
[2] Set throttle adjust collar screw against the nylon pivot block at this position

Then the cam follower comes down way too soon as I let off of the throttle. In other words as the cam follower comes down while the carb closes, it contacts the spark advance cam way to the left of the two marks where it is supposed to contact between as it comes down.

With carb butterfly valve held open, throttle lever is advanced by hand until it contacts the engine block. At this point the collar screw on the throttle control rod is set against the nylon pivot block. This results in carb opening to exactly WOT as tiller throttle handle is turned to WOT, pressing throttle lever against stop on engine.



When throttle is released, cam follower drops down and contacts cam well before the two marks


Not sure how I can have both of these conditions met at the same time. The engine will run when I set it to satisfy scenario #1, but I am afraid I am not advancing timing enough at WOT.

I hope this explanation makes sense.

All in all, the main questions I have are:
[1] When I turn the tiller throttle control to WOT, should the throttle lever stop against the engine block?
[2] Does the throttle lever need to be stopped against the engine block to fully advance the timing?
[3] **Is the cam follower supposed to leave/contact the cam between the two marks as the carb begins to open/close AND the throttle control rod be set such that the butterfly valve is at WOT with the throttle lever against the engine block? I do not see how this is physically possible on my engine.**

Tried to include all possible information.. I am continuing to research this and figure it out, as well as searching through this forum and others for any relevant information.

Thanks in advance for any info on this!!

 

[Boomhauer]

OMC instructions I'm working off of:






Youtube example of what I'm doing linked below:

Makes sense when I watch it, I can get my cam follower to act like that. However the throttle lever is not bottoming out on the engine block, so it looks like it's not advancing spark enough at WOT, as well as putting excess pressure on the carb's throttle arm after it goes past fully open (if I keep applying throttle pressure). The instructions say WOT with the throttle should line up with WOT on the carb. Ok that makes sense. But if I make that adjustment work properly, then the cam follower isn't lining up with the marks on the cam when it starts to move down. Scratching my head here. Definitely missing something.

 

[Boomhauer]

After more research I am comfortable saying the most important of the carb/timing sync is having the cam follower leave/contact the cam right between the marks on the cam. This should keep spark advance synced with throttle position/engine speed. I have seen and read that you may need to adjust this slightly in some cases depending on the engine. Mine seems to work when set right between the marks.

Regarding the procedure for Throttle Control Rod Adjustment, still not sure how you can have the above set properly, and be able to rotate the throttle lever to the stop on the engine block without binding the throttle shaft. That's where I'm left confused and feel like I'm missing something. Or there is something mechanically wrong with my system.

Took it out yesterday to try to get the carb adjusted. There is a lot of play in the throttle control which is making it hard to get the idle fine-tuned. I also need to replace the bent idle stop screw. (acts more like a cam rather than a linear adjustment due to the wobble as it rotates, for example 1/4 turn doesn't always yield same amount of adjustment)

I hooked up a tachometer to try and monitor RPMs. According to that, I was able to idle around 700-800 rpm in neutral, probably lower if I spent more time on it. At WOT it was topping out at roughly 4900 rpm, manual says it should be at least 5200 (up to 5800 I believe). Then again I have not verified my tachometer. It is the type where you wrap a signal wire around the spark plug wire. I am going to get a photo eye tachometer that looks at a marker on the flywheel for a comparison measurement. Previous owner had put a new prop on it, I believe it matches factory prop specs but I have not verified that.

At the end of the day I think I was over-thinking it, though I wanted to be as thorough as I could when setting these adjustments. The only thing left is to verify the timing/spark advance at WOT and get that adjusted to the factory spec of 30 degrees advanced.

 

[Boomhauer]

Pretty sure I have my issue figured out.

Looks like the spark advance stop bolt also serves as the high speed throttle stop. (feel free to correct me if I am wrong on that) Duh. Looking back, it should've been obvious, but with my inexperience it didn't click right away.

(I was confusing the throttle lever itself contacting the engine block with the throttle/timing cam contacting the spark advance stop bolt as the high speed throttle stop)