Mercury Mark 55A idle too high. Can’t adjust lower.

[Mcmaxie]

I can’t get the idle down to normal on my Mercury Mark 55A. When I manually turn magneto toward the block clockwise, the throttle stop adjust screw hits the magneto collar preventing it from reaching the idle position. Also the idle stop screw is preventing the low idle position. When I remove both stop screws completely, the unit idles fine.

Is there a way to drop the idle speed other than rotating the mag? Any advice much appreciated?

 

[The Force power]

Welcome to Iboats

Is the butterfly fully closed?
is the float in the Carb. working? a flooded/leaking Carb. can cause high idle

 

[racerone]

Is belt timing correct ?

 

[merc850]

It does sound like the belt position is off, try resetting the distributor pulley CW 1 tooth. This will also affect the max. spark advance by retarding it.