Armature Plate: 1974 Johnson 25 hp

[JohnAB]

As in my previous post, I have been having a reqal problem with a lack of power out of this engine. At WOT getting 1850 RPM on the water.<br /><br />Last night I checked the timing to see if the breaker points were adjusted correctly. Timing was way advanced so I removed the flywheel etc and gapped the points to 20 thou. Reassembled and rechecked timing. Now the line on the flywheel is dead center between the two marks on the lower armature plate at 1000 rpm.<br /><br />I did notice when I was adjusting the points, that the armature plate had a wee bit of play on the shaft. Is this normal or is there a worn bushing?<br /><br />Also while testing the timing I hooked up my inductive lead to the bottom coil wire. Very intermittent strobe action when I did if any at all. ALso noticed my Tiny Tach started to stop displaying the RPM once in awhile. So now I realize my bottm coil is not working properly as well and will replace it.<br /><br />Hopefully this will cure my problem.

 

[Paul Moir]

Re: Armature Plate: 1974 Johnson 25 hp

Those armature plate bearings do seem to wear out prematurely. I suspect some galvanic corrosion is responsible since that bearing acts as the sole ground for components on the plate.<br />If it's worn excessively, your timing will be thrown off by effectively changing the point gap when it wobbles. Joe Reeves has an excellent fix for this problem if your timing is being thrown off by the wobble. Check out his post here. It's a lot less complicated then what I've done. <br /><br />Good luck!