Adjusting Controls

[sharkhook]

Hello All,

Great Site long time reader first time poster

I have a 1986 85hp Force that needs to have the controls adjusted. When I try to start it in fast Idle it bucks like the gears are partially engaged. My question is does the interlock move up/down on the shift rod ? I'm afraid if I loosen the bolts to adjust the height I'll throw the shift rod way out of adjustment.

Thanks
Gravy

 

[Frank Acampora]

Re: Adjusting Controls

Before you go blindly moving anything, slow down and use logic.

1. with the control handle in upright or neutral, is the interlock in neutral and is the bent metal piece on the shift lever centered on the microswitch button?
2. Is the interlock stop plate centered with the matching cam on the control tower?
3. The two plates should mate in fast idle, preventing the shift lever from being actuated. Only enough movement to advance timing a few degrees and open the carbs a crack should be possible.
4. Does the throttle cable have a spring loaded quick connect end on it? Is the spring end out about 3/16 inch? Some engines come with a solid quick connect and use compliance in the cables to regulate the difference between shift and throttle cable. If so, disregard this paragraph.

If these are correct in neutral and the engine lower unit still feels like it is in gear, THEN:
1 remove the very small cotter and the pin that looks like part of a 12 penny nail from the coupler beneath the lower engine mount.
2. Screw in the straight rod until it bottoms then back out only enough to mate the holes--usually less than 1/2 turn. Connect everything again.
3. Check to see if the prop spins freely in both directions in neutral. If you hear a slight clicking noise when the prop is turned in neutral, then the shift linkage is biased toward either forward or reverse.

To check this, leave the control in neutral and scribe a light reference line on the shift rod. now put the control in both forward and reverse and scribe two more light lines. The distance between the neutral reference and the other two lines should be equal. Which ever distance is greater, that is the gear throw you need to adjust. Let's pretend it is biased toward forward.

NOW you go under the manifold and you will see the upper shift rod held to the actuator plate with a lower nut and an upper nut. They are self locking and are usually 9/16 but I have also seen 1/2. Since forward is down, your goal is to raise the rod slightly. Lower the bottom nut about 1/2 TURN and run the top one down to lock it. Do this until shift throw to both gears is equal.

Since clearance is limited this is difficult and patience is required. (Cursing definitely helps)You would be best to remove the air box, and should remove the battery cables since you need to access these nuts from the solenoid side of the engine. You need a long open end wrench to get in there and you will only be able to turn the nuts about 1/8 turn at a time. Then, since the wrench head is offset 15 degrees, turn it over to move the nut some more.

If too much throw in reverse, lower the upper shift rod

 

[sharkhook]

Re: Adjusting Controls

Thanks for the quick response Frank,

I'll go thru these procedures the next trip to the lake. The problem seems to be the interlock is to high. I marked the rod for neutral, but in fast neutral the towershaft stop(beveled) won't clear the interlock. That's why I was thinking I could adjust the interlock without moving the rod.

Yes to 1 and 2
1. with the control handle in upright or neutral, is the interlock in neutral and is the bent metal piece on the shift lever centered on the microswitch button?
2. Is the interlock stop plate centered with the matching cam on the control tower?

3. The two plates should mate in fast idle, preventing the shift lever from being actuated. Only enough movement to advance timing a few degrees and open the carbs a crack should be possible.

3a Not sure what you mean "mate in fast idle" do you neutral regular idle ?

4. Does the throttle cable have a spring loaded quick connect end on it? Is the spring end out about 3/16 inch? Some engines come with a solid quick connect and use compliance in the cables to regulate the difference between shift and throttle cable. If so, disregard this paragraph.

4a Yes quick connects


Check to see if the prop spins freely in both directions in neutral. If you hear a slight clicking noise when the prop is turned in neutral, then the shift linkage is biased toward either forward or reverse.

.... Yes Prop spins freely

This is where it gets tricky for me

Let's pretend it is biased toward forward.
NOW you go under the manifold and you will see the upper shift rod held to the actuator plate with a lower nut and an upper nut. They are self locking and are usually 9/16 but I have also seen 1/2. Since forward is down, your goal is to raise the rod slightly.

What will this procedure tell me ?
Screw in the straight rod until it bottoms then back out only enough to mate the holes--usually less than 1/2 turn. Connect everything again.

Once I get in front of motor this will make more since.
Thanks again
SharkHook

 

[Frank Acampora]

Re: Adjusting Controls

In neutral, the beveled stop IS supposed to hit the interlock plate. When you disable the shift for fast idle, it stops throttle before too much rpm is asked for. (limits fast idle to about 1500-2000 RPM) Otherwise, you could over-rev the engine in neutral. (this is a safety feature that no automobile has.)

When shift is enabled, because of the spring loaded throttle cable, the shift will move before throttle starts to advance. the interlock lever will move either down for forward or up for reverse and NOW the tower stop will clear it, enabling throttle and timing to advance.

In neutral, when properly adjusted, the interlock plate should ALWAYS be even with the tower stop. Since the plate moves the upper shift rod, it should be the rod that you adjust--not the interlock plate. (assuming the plate is properly positioned.) I said in question 3 that it would prevent the shift from moving. That is misleading! The control box lever prevents the shift from moving when you either press the center rubber covered button or pull out the whole handle about 1/4 inch. (depending on control box type) This disengages the shift mechanism inside the control box and allows only throttle advance.The throttle (tower) can only advance slightly because of the two interlock plates contacting each other. This is built into the engine and is not adjustable. (well, not easily adjustable)

Also, remember that because of compliance in the control cables, sometimes the system will not return to a centered neutral. It is sometimes necessary to cycle the control from forward to reverse and back to neutral several times to get it to center.

The bottom shift rod will not tell you anything. It is supposed to be screwed all the way in (clockwise) and then backed out only enough to line up the holes. If it is not screwed all the way in, then the shift linkage would be too long.

If the drive dogs are not ckicking when the prop is spun in both directions in neutral, then based upon your answers to the questions, your shift linkage IS or APPEARS TO BE properly adjusted.

At this point I would recommend looking at other areas for the problem.

Is the regular idle between 700-750 RPM in gear in the water?
Are the choke plates closing fully during a choked start?
Are the plugs clean and are all of them firing? These engines will start and run with one plug not firing. And because of the ignition type, a plug that does not fire at start or idle may fire at high speed. Thus: the engine will run really crappy at the dock yet well out on the water.
Is compression relatively equal on all cylinders?

 

[sharkhook]

Re: Adjusting Controls

The throttle (tower) can only advance slightly because of the two interlock plates contacting each other. This is built into the engine and is not adjustable. (well, not easily adjustable)

Yep, This is the problem I need about 1/32 (http://iruler.net/) or less of an inch more clearance for the plates for a smother transition to fast idle, and the linkage seems to be "Biased" towards forward. We're probably talking millimeters of adjustments.

I can't wait to get to the lake and get back on my horse she's been sick for to long, Thanks again for your advise.

Sharkhook

 

[Frank Acampora]

Re: Adjusting Controls

If the clearance is so small that you can not get enough rpm at fast idle, That means that the carbs and timing are not properly synchronized. See: If you need to screw in the idle stop screw too far in order to get the proper idle speed--all the links are interconnected--so you are advancing the tower and stop plate. The idle stop screw should be fairly close to centered in the arm. Oh, yeah! when you go to WOT, be sure the plastic stop button is in the tower arm and be sure it is not broken and contacts the engine block. WOT is not adjustable --only the timing and carb opening is.

So, what you need to do is set the screw approximately centered in the casting, then in neutral, using the ball links at the carb, set the throttle advance cam so that the line is centered on the roller on the carb arm or the roller is between the two scribed lines on the cam. (some only have 1 line, some have 2) Now go to wide open throttle and see that the butterfly plates are horizontal or very nearly so. (They should need very little to no adjustment)

Now, you need to check the timing while cranking in neutral---NOT fast idle--- Timing should be 0 degrees + - 2 deg. If it is not (especially if it is more than -2) re set it using the link at the top of the tower. NOW everything is where it should be as a synch start, and to check total advance..

The next thing to do is to check the timing at wide open throttle --30-32 degrees advance is correct. 30 is best but you can accept 32. If it is not correct, again using the link at the top of the tower re-set it to specs. Re-set it with the engine off so your fingers don't contact the flywheel and paint the engine red--Got it? Move the threaded rod 1/4 to 1/2 turn at a time until timing is correct. THE WOT TIMING IS THE IMPORTANT SETTING. It should be proper even if the idle timing is incorrect. Originally, Chrysler engines were timed at 32 degrees advance. Due to poorer quality marine gasoline, later Chryslers and Force engines were detuned slightly to 30 degrees. If you only use automobile pump gas, 32 deg will be fine.

Now, you go back and using the idle stop screw adjust the idle speed to 700-750 RPM in forward gear in the water. Note that the timing may not be 0 degrees AND the carb arm may no longer be between the scribed lines on the cam. This is correct. Now there should be enough clearance between the two shift linkage plates so that a fast idle of 1500-2000 RPM can be had.

 

[sharkhook]

Re: Adjusting Controls

Success, I was able to make the adjustments and now I'm able to use the fast idle without the boat bucking like a bronco. The adjustment was needed on the screws holding the upper shiftrod on the interlock plate. About a 1/4 inch. Now I have a new problem...

Thanks Frank

 

[Matthew A.]

Re: Adjusting Controls

Excellent thread you guys...!!!!

Frank....you rock!!