Idle timing process

[3ric]

Hello all. I have a 2001 Mercury 15M. The motor is new to me and so is the process of adjusting the timing. It runs alright, but I’m trying to get it dialed in well. I have a Clymer manual that provides pretty straightforward instructions on the subject, however I am struggling with step 1. The manual says to first set the idle screw on the carb to just off the , what I think is ,the cam follower then in a half turn to just crack the throttle open. But if I do this, the idle is so low the motor won’t start or stay running so I can’t check the timing. I don’t have a tdc tool, but would be willing to drop the $20 if necessary.

Question 1: do I need to screw in the idle set screw until it can idle at a minimum and then adjust the idle timing to get the rpms up enough to lower the idle set screw back down to where the manual says, then redo the idle timing to get the rpms up to spec ?

Q 2: the manual lists setting WOT timing first. Is this necessary? I don’t have a boat to put the motor on yet and don’t want to have a test prop made (although I may someday), but plan to have it on a boat soon. So if I can fiddle with the idle timing now and set WOT later it would satisfy my desire to continue making improvements on this motor. Can i set Idle timing before setting WOT timing?

note, I have a cheap tach and timing light.

 

[racerone]

Timing on these motors does not go out of adjustment.----Unless it has been tampered with.-----Be careful with any adjustments you make.

 

[3ric]

Noted, and good to know. and to be honest, I haven’t even broken out the timing light yet to see if it’s even off. I mostly just want to learn the process. I was a bit confused about step 1 and wondered just how rigid the chronology of the process is, and it very well may have been fiddled with.

 

[QBhoy]

So....I think that best thing I can suggest is to not worry too much over this, especially if you don’t know if it’s even an issue or required yet.
I think when you get the engine, most crucial thing is to make sure it has compression. 99% of things other than this..is a quick an easy fix on engines like this.
But all that aside...should you want to set the idle rpm...it’s easily done by ear. Get the engine warmed up to normal temp...put it in gear at lowest throttle setting and adjust the idle screw on the throttle high enough to keep running without stalling when in gear and under load...but low enough so she isn’t harsh engaging gear from neutral.
As for wot rpm and all that...things like this all depend on the boat the engine is on and props. If you’re going to that length and trying to prop perfectly...your wee tachometer will be handy to indicate that. But usually prop set up determines things like that.

 

[3ric]

I did do a compression test which yielded 104 and 105, which I assume Is pretty good as they are near identical and 4-5 lbs over spec. So I suppose if my neurotic-ness gets the best of me I can just check the timing before I get too carried away. I had/have the idle set pretty good otherwise