gap tolerances

[gmarshall43]

I have some older Johnson and Evinrude motors from the late 50's to the early 70's from 5.5 to 10 hp. Correct me if I'm wrong but the gap setting for these is .020. Should the feeler gage go through the gap smoothly or should there be a little restriction? Also is there a tolerance here, that is does the gap have to be right on .020 for the motor to start? What if the gap is off say .002, what will the result be? Will the motor still start? <br /><br />Thanks

 

[Paul Moir]

Re: gap tolerances

You should feel a little drag on the gauge as you pull it through.<br />If your gap is slightly off, it should still start as timing is not very critical at the lower rpm settings. However, I've found that if your gap is off so that your timing is off by more than 5° or so, then your spark suffers heavily since the magnet is not in the ideal position relitive to the points opening. So really, your timing can never be very far off. <br />My procedure for setting points is to set them to .020, and then use a timing light to get them dead-on. You'll notice that there are two marks on the armature plate, and two repective marks on the flywheel. One for the top spark, and one for the bottom. Each flywheel mark should appear between the two marks on the armature plate when using a timing light on each spark plug lead. <br />Setting the points to .020 gets it really close each time, but never seems to get it deadly. And I'm never very careful at setting them at .020 since I follow it up with the timing light. So there must be some tolerance there. <br />My OEM manual lists using the gap method as secondary to the timing light method.<br /><br />I hope this helps!

 

[R.Johnson]

Re: gap tolerances

The feeler guage should be a slide fit. The setting is not that critical. OMC make's a special tool for this that fit's over the crankshaft taper, and the point's are adjusted with an ohm meter, or simple continuity light.