Throttle cable adjustment

[gregtobin]

The throttle cables to my 74 Merc 1150 were frayed and I had a boat mechanic replace them. Now, when you push the control lever forward, you can feel it shift into forward, but no throttle is applied until you have taken the lever a little over 50% of its throw distance. Instead of having 90degrees of lever movement, I have 40-45 at best. Although my tach is not yet working, the motor doesn't seem to rev up to full throttle.

It seems that the cable needs adjustment.

I called the boat shop and the mechanic was out. The owner tells me that there is not much adjustment to be had on the throttle cables and that I might have some worn parts in the control box.

Can anyone shed light on this?

Thanks
Greg

 

[Silvertip]

Re: Throttle cable adjustment

No amount of cable adjustment can compensate for worn parts in the control box so the technician is correct. However, adjusting the cable is simple. Disconnect the throttle cable at the engine. Push the linkage the cable was attached to, all the way against its stop (this ensures the linkage is in the idle position). Make sure the lever on the control box is in netral. Bring the end of the cable up to the linkage on the engine. If the attachment points don't line up exactly, rotate the trunion (the threaded barrel on the cable) until the two points line up exactly. Secure the trunion and reattach the cable. Move the throttle lever full open. Check the butterflies in the carb to make sure they are perfectly horizontal in the carb throats. If they are, you are done. If they aren't you need to do a link&sync procedure or there are indeed worn parts in the control box. Link & sync is far to detailed to go into here so you should have a service manual for your engine.

 

[Chris1956]

Re: Throttle cable adjustment

Greg, To add to Slivertip's advice, with the motor off, push the throttle lever all the way forward, and watch the carbs open. They should open all the way to the stop. If not, you need to find out if the control bob had enough travel, or the motor is not set up properly. Just so you know, those control boxes had extra travel. You should be able to find the Link and Synch procedure, which had been posted by Clams Canino many times.

 

[gregtobin]

Re: Throttle cable adjustment - and Tach

Re: Throttle cable adjustment - and Tach

Thanks Chris1956 and Silvertip!
When the throttle is all the way forward, the carb plates are horizontal - fully open. So, I guess this is not the problem.
I put in new spark plugs and cleaned the carbs. Next, I'll check the timing.

I picked up a noname tach - perhaps you can give me some advice so I can use it to help me see if the motor is revving all the way. It has three spade connections in back labeled
+ - and P. I'm assuming the + and - are for battery and P is for Pulse. I'd like to test it out before putting in the dash. I'll hook up the power and put a wire on the P. Where do I get the pulse from the motor? Is there a contact on the coil or distributor?

Thanks
Greg

 

[Chris1956]

Re: Throttle cable adjustment

Greg, Outboard Tachs run off the alternator. You shoulod set the tach to 12 pole.(standard Mercury setting) There may be a plug on the front of the control with three connections. These are for the Tach. The three are +, -, and Stator AC. You can also get the stator pulse from either of the yellow wires that run down the Starboard side of the motor from the flywheel.