1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

[Frank Acampora]

Re: 1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

DAMMIT! LISTEN! Don't file the cam. Just read and follow the synchronizing instructions. Nothing on these engines EVER needs to be modified. It is just a question of starting at the correct point and setting the various adjustments correctly.

 

[TwoFish]

Re: 1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

Hi privfish.

As Frank says DON”T file anything.

Your cam is sitting where mine would be when I have the fast idle lever lifted when starting.

My cam just happens to line up with the roller on the carb at the moment. Sometimes after a link and sync the line sits slightly lower than the roller. It depends on what propeller I have on when setting the motor up. The larger prop requires more power from the motor to idle in gear at 750 rpm so the line on the cam is lower as this setting opens the carb slightly more to supply power the larger prop. It also has a higher idle speed when in neutral with the larger prop as the carb is open slightly more than it would be if I set the idle in gear with the smaller prop.

Something is a miss at the moment with your setup as you have already worked out.

The link and sync will only work if everything else is OK on the motor. Eg If you have low compression the throttle will need to be open much wider to supply enough power to turn the prop at the correct speed than it would if the motor was OK. What would happen then is when you put the motor into neutral it would rev very high as it has next to no resistance when not under a load.

A couple of things to check.

1. Is the compression OK.

2. Is the return spring on the carb working? Will the cam turn further if you give it a gentle push?

3. Does the cam move when you lift the fast idle lever on the controls? When you push the lever down again does the cam return to it’s previous position? You may have a problem with this mechanism.

4. If you disconnect the end nut on the throttle cable does this allow the mark on the cam to return closer to the roller on the carb? Cable may be binding.

5. What is the timing set to at the moment?

Doing a link and sync can be quite challenging the first few times until you work out what it is you are doing and why. We may need to start again and do it a step at a time to work out what is going wrong. You seem to know which parts to adjust but I have attached a labelled photo for reference.

I’d run through the procedure with you using my motor but as you can see from the other photo it wouldn’t work very well at the moment

Cheers

TwoFish

 

[Frank Acampora]

Re: 1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

Sometimes I get a bit frustrated. You have a problem and will not solve it by grinding metal off engine parts or doing a half-fast job. Start at the beginning and set everything back to factory specs.

1. Disconnect the ball link at the timing tower and move the throttle cam back out of the way. Let the carb butterfly snap closed.
2. Move the throttle cam until the scribed line touches the roller at a tangent.
3. The roller is mounted on an offset screw. Loosen the nut and turn the screw until the roller just touches the cam. There should be no gap and it should not open the butterfly any amount. Tighten the nut.
4. Move the throttle lever to wide open throttle and adjust both ball links evenly until the butterfly is horizontal. Attach the removed link.
5. Now, static time the engine to 28 degrees before top dead center at wide open throttle.
6. Return the throttle lever to neutral and adjust the spring loaded quick-connect on the cable threads. the center spring-loaded portion should protrude about 1/4 inch with the idle stop screw hard against the block so the timing tower is fully retracted. IF YOU CAN NOT DO THIS the throttle cable is in the wrong hole inside the control box. Open the control box and move the cable to a different hole in the lever.
7. Start the engine in the water and using the idle stop screw adjust the idle to 700-750 RPM in the water in forward gear. If you move the idle stop screw a significant amount, re-adjust the spring loaded quick-connect.

At this point the scribed line on the throttle cam should be slightly below the center of the roller--less than 1/8 inch

 

[Jiggz]

Re: 1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

If you have a problem following the link and synch in the sticky threads, do the following: But before continuing on, you are correct your cam is not set properly but there are three adjustments that can make this happen. First the idle screw adj., 2nd, the ball-link connecting the timing tower to the throttle valve arms and finally the control cable. So you need to do the following so the control cam will come down more.
1. Unscrew the idle screw adjustment all the way back flush with the timing tower arm it is screwed in. Did the cam went up or pulled back to lower the rpm? If not continue on.

2. Loosen the ball linkage and shortened its length by screwing its ball end in and locking it with its lock nut. You can try three turns first and if the cam pulls back then you can do more until the line on the cam is level with the eccentric screw's slot. Note these two ball ends do break easily after years of usage. It is better you dismount the brass screw from the cam and do the turning from there. Make sure you reconnect it to check the position of the cam.

3. If the two steps above still does not move the cam, disconnect the control cable from the timing control arm. The cam better drop down to its lowest position with a little push. If it doesn't there is something binding either with the tower itself or the trigger plate.

Post back.

 

[privfisher]

Re: 1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

Sometimes I get a bit frustrated. You have a problem and will not solve it by grinding metal off engine parts or doing a half-fast job. Start at the beginning and set everything back to factory specs.

1. Disconnect the ball link at the timing tower and move the throttle cam back out of the way. Let the carb butterfly snap closed.
2. Move the throttle cam until the scribed line touches the roller at a tangent.
3. The roller is mounted on an offset screw. Loosen the nut and turn the screw until the roller just touches the cam. There should be no gap and it should not open the butterfly any amount. Tighten the nut.
4. Move the throttle lever to wide open throttle and adjust both ball links evenly until the butterfly is horizontal. Attach the removed link.
5. Now, static time the engine to 28 degrees before top dead center at wide open throttle.
6. Return the throttle lever to neutral and adjust the spring loaded quick-connect on the cable threads. the center spring-loaded portion should protrude about 1/4 inch with the idle stop screw hard against the block so the timing tower is fully retracted. IF YOU CAN NOT DO THIS the throttle cable is in the wrong hole inside the control box. Open the control box and move the cable to a different hole in the lever.
7. Start the engine in the water and using the idle stop screw adjust the idle to 700-750 RPM in the water in forward gear. If you move the idle stop screw a significant amount, re-adjust the spring loaded quick-connect.

At this point the scribed line on the throttle cam should be slightly below the center of the roller--less than 1/8 inch

No problem Frank I know it can be very frustrating trying to help someone out, especially when not face to face.
I havent filed anything down, the more I have read these posts. It's so frustrating because it seems like I'm so close to having it run perfect. I have not checked the timing. I bought the boat without checking timing and compression. I know thats not good, but it was such a good deal I couldnt pass it up. I went by how smooth it ran, it had a nice stream of water coming from water pump, and it shifted very smooth. Lower unit oil looked good too. So I took the mans word I bought it from. Knowing it needed some adjustments to be in good running order. So thats where I stand now, trying to fix the adjustments.
I am very thankful for all your advice. No hard feelings

 

[privfisher]

Re: 1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

Ok, been trying to adjust all this, in between job and small time I have til the weekend. I dont have much time before I head to work. So here is what I have done so far.
I have disconnected the little ball connection to the cam. The spring on the roller was a little sticky before it returned the carb completely closed, as I moved it back and forth, it seemed to snap back in place to shut the carb.
Next I adjusted the roller, cam to line up just centered on the line, like your pics above. This is while it is in neutral.
I adjusted the the two ends on the ball/throttle connnections, and put nut back on cam.
Now when the cam is adjusted to the point where centered with the cam, it is still just pushing a tad on the cam, also adjusted the cam roller screw, but still pushing just enough for carb to be open to cause high idle.
Now if I pull tower arm back while in neutral, it will move back almost 3/4 to an 1''.
I have not checked compression, nor timimg. So I will have to do that this weekend.
So from what I have read that everyone has posted, it seems to me it could be throttle cable not completely returning to idle, or possibly the throttle tower having a problem. Am I on the right track? Can I pull out slack by adjusting spring loaded cable at the control lever? I will follow more of the steps below that are listed by Juggz too. I dont wanna move to fast and get wreckless, and break or tear something up. Its so close to running great. I will post follow up posts as I keep working on it. Thanks for all your help!

 

[TwoFish]

Re: 1992 70hp Force motor cam shaft just a hair forward to much, causing high idle

Slow and easy is a good way to go.

The carb should close smoothly on it own. If it is sticking you need to find out why.

It does sound like the main control cable may be sticking. I’d disconnect it and try to work the tower arm manually to see if there is any problem with it. I have read posts where the bearings that the tower arm runs in can wear and cause slack in the system. Back the Idle adjustment screw on the tower out like Jiggz mentioned and then adjust the ball/ throttle connections to get the marks to line up. If the system works at this stage connect the main throttle cable after adjusting it for length and see what happens.

Your compression figures will be interesting to see.

Good Luck