How Important is OMC Ignition Timing?

[aquasonic]

Although I have gone completely through quite a few ignition plates at this point, and enjoyed the results of the work, I have yet to actually adjust the ignition timing on any of my OMC outboards.

I gather that once the points are set at 0.020", the timing is close, but it can still be adjusted for an even better running motor.

I would appreciate it if anyone can elaborate on the importance and the procedure.

Thanks

[fleetwin]

You are correct, setting the points to .020" is usually "close enough". Setting the points precisely requires one of the timing fixture tools, a decent analog ohm meter, and a timing light. There are two "timing marks" on the mag plate, one mark is used for "new points", the other is used for an existing set of points, there are two marks on the flywheel as well, one for each set of points. The extra timing mark is used for new points to account for initial rubbing block wear. Sometimes it is recommended to set new points at .022" for this same reason.
So, is all this extra effort "worth it"? I guess I would say that if you have the correct timing fixture, than it is definitely worth spending a few extra minutes to set the points precisely. Setting the points precisely will probably help the engine idle as close to perfectly as it can. But, there are some factors to consider before spending the money on a fixture and extra time doing the procedure precisely. First, the point timing is affecting by any sideways slop in the mag plate or upper crank bearing/bushing. In other words, spending extra time and money on an engine with a sloppy mag plate might not be worth the extra effort.
You can still check the point timing with a timing light after simply "setting the points to .020", to see if the timing is correct/close enough.

[cajuncook1]

Frank makes outstanding timing fixtures for OMC motors and they are very well made and very reasonably priced. I have the set and they work great

PM Frank or go here

http://www.franksoutboardtools.com/

Here is a You Tube video to get a general idea how use the timing fixtures. (put the flywheel nut on after you put on the timing fixture) The guy who made the video forgot to put the flywheel nut on.

https://www.youtube.com/watch?v=eNK2TEeQQv0

.

[chris-p]

Yeah, Franks fixtures are A1!

The important thing, more than getting each one exact, is getting them exactly 180 degrees apart, for the low idle. You just cannot do that with feeler gauges alone.

[wbeaton]

I set up hundreds of motors without the timing tool and they all worked just fine. Then one day I tried a timing tool and I Was sold. It was faster and provided a perfect spark. I would never went back to the feeler gauge. I use a buzz box instead of a multimeter. It works much better and you don’t have to remove the wires to the points.

Wayne
Upper Canada Chapter

uccaomci.com

[chinewalker]

As noted above, getting the points to .020 is well within the ballpark and the motors generally run well like that. And then you get one where you set the timing perfectly and you note that the motor starts first time, about two bumps into that first pull. And it idles so slow you can almost count the revolutions. And you realize that the ballpark just isn’t close enough.

[jay]

wbeaton – can you explain what a "buzz box" is? I have Franks tool and would love to get better at timing these things. Nothing is nicer than an oldie that pulls over and starts on the first tug!

Jay

[vintin]

I use a digital volt meter and don’t disconnect any wiring. When the points are closed I get a reading of about .6 ohms which is probably the volt meter leads and when the points open I get a reading of about about 1.2 ohms which is the resistance in the coil primary windings.

[wbeaton]

quote Jay:

wbeaton – can you explain what a “buzz box” is? I have Franks tool and would love to get better at timing these things. Nothing is nicer than an oldie that pulls over and starts on the first tug!

Jay

VinTin probably has a better multimeter than me. I use the buzzbox in the link below. I can clip the leads to the magneto and keep both hands and eyes on the timing tool and points. The unit has a buzzer so there is no need to watch/hold the multimeter while you set it. It is a small thing, but anything that makes life in the shop a little easier is good with me. The buzzbox also works great on 4 cyl Mercurys.

http://www.skygeek.com/action-air-22296 … nizer.html

Wayne
Upper Canada Chapter

uccaomci.com

[jay]

Thanks for the info gents. Very appreciated. A few motors getting ready for some tuning this weekend with the ice finally gone (mostly)

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