How Important is OMC Ignition Timing?

[Steve A W]

#14591

Jay
My craftsman digital multi meter has an audible setting on the
continuity setting.

Steve A W

Member of the MOB chapter.
I live in Northwest Indiana

[RICHARD A. WHITE]

#14592

So the buzz box/audible chirp or what ever is to tell you when the points open? I have always just watched for them to open then set them at .02… I can see how this "other" method would be so much more accurate and definitely better.

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[wbeaton]

#14594

quote Richard A. White:

So the buzz box/audible chirp or what ever is to tell you when the points open? I have always just watched for them to open then set them at .02… I can see how this "other" method would be so much more accurate and definitely better.

Yes, the buzz box/multimeter will give an audible tone or give a visual sign that the points open/closed. Coupled with the timing tool it ensures perfect timing.

Wayne
Upper Canada Chapter

uccaomci.com

[legendre]

#14595

So.. could someone who +does+ own one of these tools be so kind as to apply it to a Johnson TD20 and then take measurements of the actual timing datum – either by means of a degree wheel or a dial indicator-type timing gauge?

I’d do it myself, but I don’t see any timing marks on the TD20 flywheel.. nor any marks on the magneto plate, for that matter.

BTW – when using the timing tool, is the magneto set at full advance (fast) or full retard (slow/stop)?

[frankr]

#14605

The factory service manuals say to have it at WOT, but the fact is it really doesn’t matter. The only reason I can see for saying to have it at WOT is that would hold the armature plate steady while you are messing with it.

[legendre]

#14607

quote FrankR:

The factory service manuals say to have it at WOT, but the fact is it really doesn’t matter. The only reason I can see for saying to have it at WOT is that would hold the armature plate steady while you are messing with it.

Ah of course! You’re right, it doesn’t matter – as we’re only concerned with the angular relationship between the armature plate and the points cam on the crankshaft.. how far one leads or lags the other.

What matters in this case is the angular displacement of the armature plate from the crank position. If the plate moves, the crankshaft would be moved to reestablish alignment of the marks, or vice-versa.

Actual position of the armature plate is only of concern if we’re measuring timing angle with respect to TDC, which is a fixed point of reference.

Thanks for catching my blunder! Very much appreciated.

[grover]

#14615

Once I used a timing fixture, I never used a feeler gauge again. The spark is hot and the motors start and run noticeably better.

[elgin2]

#14630

Franks tools takes all the guess-work out of timing for sure.

[Tom]

#14631

OK, this covers how to determine when the points open. If you don’t have a timing tool, you can still get this done… I use some kind of stationary pointer that can be screwed on to the block, and get close to the flywheel.

First, make sure the mag plate is locked down and won’t move. Adjust the first set of points using a feeler gauge, then get the flywheel to where that set of points is just opening. Put a mark on the flywheel where the pointer is. Then use a tape measure to determine the circumference of the flywheel. At one half the circumference from the first mark, put a second mark. (This is 180 degrees from the first mark.) Line the second mark up with the pointer, then adjust the second set of points to where they just open.

I was quite surprised how far off the initial settings (just using gap) were on a Scott 10 hp Pennant I had a while back. It was probably 15 or 20 degrees off. The motor ran better, and idled a LOT better with the timing adjusted correctly.

Tom

[aquasonic]

#14632

Many thanks to all who weighed in on this subject. This thread has been very educational for me, and it has convinced me to purchase one of Frank’s timing fixtures. It will be interesting to see the results first hand.