Timing adjustment

[Themanofsteel]

I trying to adjust the timing on my Mercury 150 outboard 1982. When adjusting the “primary pickup”, the spec say 11 ATDC. I follow all the steps in the manual, see attached photo, but the timing light shows 20 BTDC. I can’t adjust to 11 ATDC. I must be doing something wrong. Could use some help with this.

I set the timing light to 11 ATDC.

 

[Chris1956]

Set your timing light to zero, and read timing decal. Did you set timing indicator to TDC? You should probably do that, before timing motor.

Primary pickup timing on typical ADI ignition should be 2-9* ATDC. Are your specs from a OEM service manual or some other place?

 

[Themanofsteel]

The manual is the original manual for this engine. I followed the step for timing. Set the first cylinder to TDC. The indicator was right on the.462 mark. I assume that is TDC or is zero on the flywheel TDC?

Also, are the numbers to the right of 0 on the flywheel ATDC or to the left of 0?

 

[Themanofsteel]

Here are 3 snapshots of the light.
What is the Primary Pickup anyways?

 

[racerone]

Set maximum timing advance.------Idle timing looks after itself.-----Read up on what ----" idle pick-up " -----means.------Be very careful if you decide to make adjustments as timing is set at the factory and rarely needs to be adjusted.

 

[Themanofsteel]

Ok. So skip the part about adjusting Primary Pickup? I want to check the timing first before tinkering with it. My engine is sputtering and I'm not getting full power. My stator recently went out and I replaced it.

I've checked an a number of things related to sputtering and the engine still sputters so I want to check the timing and avoid tinkering with it if I don't need to.

 

[Themanofsteel]

Another question, do I need the Idle Stabilizer. Can I/should I remove it?

 

[Chris1956]

The .462 inch mark is used to set the timing pointer accurately. When the timing pointer is set properly, and it indicates .462", the piston will be nearly 1/2 inch below TDC.

So, set the #1 cylinder to TDC using a screwdriver. Accurately measure (or use dial indicator) from top of cylinder head to top of piston. Add .462 inches to that measurement. Now back piston down until your measurement SUM is reached. Adjust timing pointer to read .462" BTDC.

Now redo your timing procedure. Disconnect idle stabilizer. Most never reconnect it. Primary pickup timing synches the carbs to the timing. It is very important to get it between 0-9* ATDC. The easy way is to remove spark plugs 2-6, and install them into their wires and ground them.

Install the timing light on #1. Timing light s/b set to zero. Set throttle until carbs are ready to open, but still closed. Crank motor and observe timing on flywheel. Adjust primary pickup set screw (about 1/2 way up throttle arm), until timing is in the range of 0-9*ATDC. This must be done, w/o changing position of carb throttle plates. They must remain closed, but ready to open.

Now advance throttle all the way and check timing. Max spark advance should be 21* BTDC. Adjust Max timing set screw (above mid point of throttle arm), to stop timing advance at 21* BTDC.

Install spark plugs and start her on a flusher. Using idle stop screw and throttle cable barrel adjustment set idle RPM to about 800RPM. You may need to further adjust it when on the water.

 

[Themanofsteel]

Ok. One question, why does the manual say 18° max timing at cranking? I read somewhere XR2 set at 21°. Mine is not a XR2. Should I still set to 21°

 

[Chris1956]

If manual says 18* BTDC, I would stick with that.

 

[Themanofsteel]

I completed the timing and everything is fine now. No more sputtering.