Need help understanding Primary Pickup Timing Adjustment

[hkeiner]

I have a 1996 Mercury 150 V6 carbed outboard motor. I pretty much understand the link and sync steps except for the Primary Pickup Timing Adjustment step. I am just not clear on what the idle timing specs mean and figure I may be misunderstanding something. I figure it is better that clear it up before I mess up my motor by setting the idle timing wrong. I do understand what TDC, BTDC, and ATDC mean and how to set timing to a specified degree with a timing light and timing pointer and with engine cranked with starter or running at idle. However, these are my questions:

1) What are the Idle Speed/Pickup Timing specs of 0 degrees to 9 degrees ATDC intended to mean? Is it a range of acceptable idle timing settings or are the 0 degrees and 9 degree ATDC specs discrete and applicable to different timing steps?

2) Should one set the timing to 0 degrees, 9 degrees ATDC, or the midway point between these two settings, when using a timing light in step B below?

3) If the final timing setting (i.e., adjustment of the throttle primary pickup screw in step F below) is based upon RPM with engine running, and not based on a timing light with engine cranked by starter, why don't they just suggest a single timing light spec to start with, rather than a range? It does not seem logical.

4) Finally, if one wants to merely check that the Primary Pickup Timing Adjustment is OK, would one only confirm that the timing is between the range of 0 degrees and 9 degress ATDC usng a timing light with engine idling and that the idle RPM is within the 600 to 700 RPM range using a good tachometer? And if so, leave the throttle primary pickup screw alone and don't mess with it!!

Any insight on this would be very much appreciated.
Regards


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The Mercury and Seloc manuals provides (in brief) the following relevant guidance:

PRIMARY PICKUP TIMEING ADJUSTMENT

A) Disconnect the idle stabilizer box, remove spark plugs, and connect timing light to number one plug wire.

B) With engine in neutral, hold the throttle arm so that the idle stop screw is against the idle stop. Crank engine with starter motor ands adjust the throttle primary pickup screw to align specified throttle primary pickup mark on the timing decal with the timing pointer. Retighten nut on adjustment screw.

C) All timing adjustments made to the outboard under cranking speed condition should be verified with the outboard running and adjustments made if necessary. This is due to the advance charge characteristics of the individual ignition systems.

IDLE SPEED ADJUSTMENT

D) Reconnect the idle stabilizer box, remove the timing light, and install all spark plugs. With engine in water, start engine and allow it to warm up. Place engine in gear.

F) If engine RPM is above or below the recommended RPM specifications, readjust the throttle primary pickup screw to attain the recommended RPM. Retighten nut on adjustment screw.

 

[Don S]

Re: Need help understanding Primary Pickup Timing Adjustment

1) What are the Idle Speed/Pickup Timing specs of 0 degrees to 9 degrees ATDC intended to mean? Is it a range of acceptable idle timing settings or are the 0 degrees and 9 degree ATDC specs discrete and applicable to different timing steps?

This is for the initial settings when done while cranking the engine over with the starter. A fully charged battery or one with a charger on it may get a completely different reading than one with half a charge. But it could still be within range when setting since it will be verified by idle rpm.

2) Should one set the timing to 0 degrees, 9 degrees ATDC, or the midway point between these two settings, when using a timing light in step B below?

Depends on engine rpm while cranking. Set it at mid range and check when running.

3) If the final timing setting (i.e., adjustment of the throttle primary pickup screw in step F below) is based upon RPM with engine running, and not based on a timing light with engine cranked by starter, why don't they just suggest a single timing light spec to start with, rather than a range? It does not seem logical.

This method was more accurate and repeatable.

4) Finally, if one wants to merely check that the Primary Pickup Timing Adjustment is OK, would one only confirm that the timing is between the range of 0 degrees and 9 degress ATDC usng a timing light with engine idling and that the idle RPM is within the 600 to 700 RPM range using a good tachometer? And if so, leave the throttle primary pickup screw alone and don't mess with it!!

To check, make sure the engine idles at the proper rpm, then pull the plugs and check the pickup timing. It should be between 0° and 9° BTDC

 

[hkeiner]

Re: Need help understanding Primary Pickup Timing Adjustment

To check, make sure the engine idles at the proper rpm, then pull the plugs and check the pickup timing. It should be between 0° and 9° BTDC

Thanks for your answer. It cleared things up for me. However, just to make sure I got it right, did you mean to say 9 degrees ATDC and not 9 degrees BTDC?

Thanks

 

[Don S]

Re: Need help understanding Primary Pickup Timing Adjustment

Yea, wrong finger moved......... ATDC:%

 

[hkeiner]

Re: Need help understanding Primary Pickup Timing Adjustment

Don S,

The directions you provided to me on doing/checking the Primary Pickup Timing Adjustment were excellent. It gave me the practical and detail instructions to check/adjust this timing without the risk of doing it the wrong way. Since I have your attention, I was hoping you could confirm my understanding on how to check/adjust the Maximum Timing Adjustment. I am certain on how to do the preliminary adjustment using the timing light to adjust the maximum spark advance screw to get 21 degrees BTDC. However, I am not sure on the most practical and safe way do the final timing timing check when running the engine at WOT. This is what I think I should do:

1) Using the timing light to adjust the maximum spark advance screw to get 21 degrees BTDC, as per the Mercury manual instructions described below.

2) Drive the boat out on the water with the motor at WOT, the cover removed, and the timing light connected to the number one cylinder. Use the timing light to note whether the timing pointer aligns EXACTLY with the 19 degrees BTDC mark on the flywheel. If it does, I am done. The maximum timing is OK.

3) If the timing pointer does not EXACTLY align with the 19 degree BTDC mark, note how many degrees the timing pointer is before or after the 19 degree BTDC mark on the flywheel.

4) Repeat step 1) above, except this time adjust the timing pointer before or after the 21 degree BTDC mark the same number of degrees that the timing was noted to be off of the 19 degree BTDC mark in step 3 above.

5) Repeat step 2) above. The timing pointer should be now aligned EXACTLY on the 19 degree BTDC mark. If it is still off, repeat above steps until the timing is EXACTLY 19 degrees BTDC with the motor running at WOT.


Is my understanding correct or is there a better or more correct way to do this? Also, how critical is it for the timing to be EXACTLY at the specs? That is, is it OK to set the timing retarded by one or two degrees from spec in order to avoid potential ping if too low octaine or poor gas is inadvertanly used?

Thanks
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Mercury manual instructions:

- With engine in neutral, move the throttle lever to place the maximum spark advance screw against stop. Crank engine with starter motor and adjust maximu spark advance timing mark with timing pointer per specifications. Tighten adjustment screw.

- All timing adjustment made to outboard under cranking speed should be verified with outboard running and adjustments made if necessary.

 

[timmathis]

Re: Need help understanding Primary Pickup Timing Adjustment

I set mine at cranking speed. Not running under a bridge in the shade. Then I will double check it while running under the bridge out of gear It does not have to be WOT to reach max timing it should reach max at about 2200- 2500 rpm's. Plus it is hard to see the timing mark under the sun. You can advance the throttle by hand to reach max timing.
It sure is ez to see in the shade.
Also it is not safe to lean over the motor while going down the lake at WOT. My way one person can set the timing. It would take 2 people, The other way. One to drive while the other checks the light that will be hard to see anyway. Tim

 

[Don S]

Re: Need help understanding Primary Pickup Timing Adjustment

Put a charger on the battery, on high. When the battery is fully charged, remove the plugs, open the throttle with the max advance screw agains the stop and crank the engine. If you have the proper timing. .
After that, it's what ever you feel comfortable with on hanging over the back of the boat while looking at impossible marks in variying degrees of light. Or get a test prop that loads the engine an try it.

 

[hkeiner]

Re: Need help understanding Primary Pickup Timing Adjustment

Guys,

Thanks for the advice on some alternatives to checking the maximum timing. The boat goes about 45-50mph at full speed and it did seem somewhat scary, dangerous, and crazy to check the timing while running the boat at full speed on the water.

Regards

 

[Don S]

Re: Need help understanding Primary Pickup Timing Adjustment

Not sure what I was thinking about when I said run the engine at 5000 rpm for a few seconds.(I edited it out of my previous reply) You MUST have it at WOT just to get the screw for the max timing against the stop.