Timing marks

My 1974 15hp has breaker point ignition. I have set the points as best I can but I would like to be sure that the timing is spot on. The manual says I can use a timing light for this but where are the timing marks? There are 4 likely looking marks on the flywheel which isn't very helpful on a 2 cylinder engine unless they are for high and low RPM timing setting. All wisdom on this gratefully received!

Re: Timing marks

There are timing devices for those magnetos. They're T-bars that go on in place of the flywheel. The breakers should open when the mark on the T-bar lies between two timing marks on the mag plate. Dealers have those. That's the only way of setting the timing that I'm aware of. But if your points are at .020, the timing will be well within in the ballpark.<br /><br />If you want to check the timing with a light, pull the sparkplugs. Find top dead center for the top sparkplug (I usually stick a pencil with the eraser end against the piston for ballparking TDC). Check for what marks line up with what reference. That should get you going.<br /><br />The key isn't so much to set the timing individually, but as a pair. With a feeler gauge all you can do is set them individually. But that doesn't guarantee that the plugs will fire exactly 180 degrees apart. They could both be right at .020 and still be a few degrees off. When timing with the T-bar, it isn't uncommon for one or both sets of points to vary from that by a few thousnadths.<br /><br />What you can do with a timing light is verify that the sparkplugs are firing 180 degrees apart. For that you need to accurately nail-down TDC markings and make another straight across the other side of the flywheel for #2. If they fire a few degrees off you'll have to start playing with points gaps. That'll make the motor run smoothest, but few people would ever notice the difference.

Re: Timing marks

There are a set of timing marks on the magneto plate. They are 2 parallel lines about 1/8" apart. You hook up a timing lite and point it at the marks and you will see a mark on the flywheel line up, or should line up inside the 2 parallel lines. That shows the points are "firing" within the specs. If you change the gap, the timing marks will change. If both points are not gapped the same, then the marks will be different from the top to bottom cylinder.<br /><br />This does not tell the degrees of advance, but shows if the points are "synched" correctly for the smoothest engine operation. Play with the point gap and you will see the marks "move".