Link n sync 1975 40hp Johnson

[brian3127]

I have a clymer manual for my motor.
And to do a link n sync it says to move the throttle control until the intake manifold projection is centered between the 2 throttle cam marks.
If the throttle valve is not closed with the cam follower roller touching the cam, loosen the throttle arm clamp screw and adjust.
That part is easy to figure out now the next step is confusing.

Manually rotate armature base to full advance position. Adjust control rod collar to provide 1/32 in. Clearance at the pivot pin.

The thing I don't understand. Is I loosen the screw to adjust the 1/32 in. Gap and then the throttle valve closes because the set screw is holding the throttle valve open.

Do I hold the throttle valve fully open and then set the gap I don't get it

And when I do the first step I push the throttle to wot and the throttle valve is open at about 1/2open

 

[brian3127]

Re: Link n sync 1975 40hp Johnson

anyone want to take a stab at this one by the way the motor i have is a 1975 40hp johnson (40el75c)

 

[gm280]

Re: Link n sync 1975 40hp Johnson

I have a 1976 40 HP Johnson engine that I am presently rebuilding. It is nearly complete now and I will be doing the same Link 'N Sync as well. But I have the original Johnson 1976 40 HP Shop Manual and will follow their instructions for that effort. The 1/32" gap you are referring to is totally visible on my setup and since I haven't moved any adjustments concerning the carb and ignition, it may go back without much trouble. I know there are directions available here on iboats for your exact needs. Maybe you could research that and read for better understanding. You could even PM the folks that posted such info for further clarification... I can't direct you on how to do that effort (yet) because I haven't got to that point yet myself...

 

[brian3127]

Re: Link n sync 1975 40hp Johnson

The GPS on my phone said I was going 16 mph at 3800 rpms. Looking into the carberator at the dock with the throttle wot ( engine not running) the throttle valve is only open about half way. I did the link and sync the way the book said to do it. I don't understand the throttle valve should be wide open. Then I opened the throttle valve all the way open and set the screw to 1/32 but when I pulled the throttle back to idle position the follower wasn't on the armeture so I redid it the way the book said to do it.

 

[Joe Reeves]

Re: Link n sync 1975 40hp Johnson

Should you be speaking of the linkage rod that runs from the magneto armature plate to the throttle cam roller...........

(Synchronization Of Older 2 Cyl Engines)
(Such As The 28, 33, 40hp Etc models )

On the linkage that runs from the armature plate (the plate the coils & points set on) to the carburetor throttle roller, loosen the set screw on the brass collar that you see there and temporarily move it away from the armature plate/vertical throttle arm clevis (clevis is that thing the linkage rod slides through). We'll refer to that vertical throttle arm/armature plate clevis simply as the "clevis" from this point on.

Look at the cam that's attached to the front of the armature plate.... the cam that slides up against the carburetor throttle roller. You'll notice that there's a scribe mark on it. Also notice that at the top portion of the intake manifold there is a raised portion, that top portion forming a point. The carburetor roller should contact the cam and just start to open the throttle butterfly when the scribe mark is dead center with that point.

With the engine in gear (not running of course) have the armature plate advanced all the way (by hand) so that it is up against its stop. Now adjust the brass collar (set screw) on that associated linkage rod so that it is up against the clevis. It should be adjusted so that there is either no play, or just a hairs play between the collar and the clevis.

At this point, the armature plate movement is not advancing the throttle butterfly via the rod movement, but further movement of the throttle control, although the armature plate cannot move any farther, causes the tension spring at the armature plate to allow the vertical throttle arm to move farther which now advances the carburetor throttle butterfly via the rod. When fully advanced (full throttle), the carburetor throttle butterfly should be fully opened (horizontal).

If all else with your engine is as it should be, that should do it.

 

[brian3127]

Re: Link n sync 1975 40hp Johnson

thanks Joe Reeves i will do that after work if the rain stops.

so advancing the armature plate to its stop the follower should still be in contact with the plate. right?

 

[Joe Reeves]

Re: Link n sync 1975 40hp Johnson

so advancing the armature plate to its stop the follower should still be in contact with the plate. right?

The roller should be in contact with the cam that is attached to the armature plate when fully advanced if that's what you're asking. It is at that point where the rod linkage adjustment takes place as per my post/reply above.

 

[brian3127]

Re: Link n sync 1975 40hp Johnson

yeah thats what i was asking

next question all the plastic retainer nut are worn with flat spots on them so everything is sloppy is that ok or should i get new ones to tighten everything up

 

[Joe Reeves]

Re: Link n sync 1975 40hp Johnson

Explain.... What plastic retainer nuts?

 

[brian3127]

Re: Link n sync 1975 40hp Johnson

It doesn't matter now about the plastic retainer nuts I'm running at wot with the throttle butterfly wide open. I wasn't doing it right I didn't have it in gear when I was at the dock setting the timing. So the motor is running great thanks for the help. But it's still only running at 3800 rpm. Would that be prop issues or something else.