1978 50hp Mercury timing and synchronization

[lgaytan]

Hello does anyone knows what this screw is for? I don't see it in the service manual that I have, the issue with this screw is that when trying to push full throttle it hits the bar in the picture and the carburetor can't go WOT, is this screw from design, how come I doesn't show on the manual?

 

[lgaytan]

Anyone?

 

[Texasmark]

Move your throttle lever back and forth and watch what moves inside the engine compartment. Usually at least one of the levers that move....one is for carb butterfly control and the other is for timing changes, sets the engine timing to set the idle speed (on some engines like mine) and the other would be a stop for controlling the amount the carb's butterflies move.

On my engines, idle speed of 650 RPM was set by the timing adjustment around 0 degrees. The screw on that arm extending up from the throttle control is used for setting the idle speed minimum advancement. The lever upon which this adjustment screw is attached, extends to components up under the flywheel for controlling the timing of the stators to the magnets on the flywheel and at WOT the timing will be 20-24 degrees BTDC, much earlier than that required at idle.

 

[lgaytan]

My outboard has 4 stop screws, I have identified 3 of them that are in the manuals I have, a Service manual and the Seloc, but there is a 4th one I don't see in this manuals, so I'm wondering if this screw was added not in the design intent of this mechanism. see the picture below.

 

[Chris1956]

There is always an adjustment for idle pickup timing. You will be able to vary the timing when the carbs start to open.

 

[lgaytan]

So I've searched used parts in ebay just to see if that screw is present, and I don't see it now I think somebody put it there, maybe with a reason, but I dont think it is design intent. I will remove and see what happens... hopefully I dont break anything. Still the manual doesnt tell me what it does so even if I leave it, I don't know what to do with it.