1975 Evinrude 9.9 - part 2

This is the same engine I posted about last week...original problem (no spark to one cylinder) appears to have been resolved with a new plug...starts easily now and runs but has a definite mis-fire especially when quickly reducing the throttle from higher to lower speed...

mdl 10524C
new coils/wires/boots
new plugs ngk b7hs .030
top cyl 95 psi btm cyl 100
good blue spark jumping 3/8" gap using tester

points & condensors are roughly 3-4 years old but have maybe 5-6 hours on them...i have checked the point gaps and they are .020 (should I replace?)

I have done nothing with carb/fuel system other than checked the filter screen

I'm not sure where to go from here and i'm open to suggestions...thanks!

- Mark

Re: 1975 Evinrude 9.9 - part 2

Glad your making some progress. See if you have any play on the points cam or even the crank shaft. That could cause your points to open wider than .020 and check your flywheel magnets to make sure they are not loose. Clean your points as well. Rick.

Re: 1975 Evinrude 9.9 - part 2

I am kind of with Rick. Clean your points well. I dip a white business card in laquer thinner and pull it through the points and blow them hard with compressed air. Usually does the trick. Before cleaning them you could also disconnect all the wires and put a multimeter on the point wire and the other lead on the powerhead ground. When the points are closed the continuity should indicate a closed circuit and when open it should indicate an open circuit. My meter uses a buzzer to indicate a continuous (closed) circuit. Anyways, turn the points cam on the motor and ensure that the meter only shows one open circuit per one complete turn. 2ndly, turn the points cam very slowing and when the circuit "just opens", stop turning the cam. Now take the flywheel and without moving anything see if the timing marks on the flywheel line up with the marks on the timing plate. If they do then you know your timing is correct. verify the gap and use that gap (even if it is not 0.020", but most likely it will be or very close to that gap). Do this for both points. Then clean them up and try the motor again.

Re: 1975 Evinrude 9.9 - part 2

Thanks guys for the replies...I went ahead & ordered points/condensors today, i figured for the $30 or so I may as well replace vs clean since I'll be under the flywheel anyway to do the continuity testing & timing checks described by optsy as well as to check for play in point cam and/or crank shaft...

questions: is any amount of play acceptable? what is the remedy if there is play??

Also if I'm understanding this correctly, timing is the point where the points first open but they are obviously not at the full gap of .020 at this point...if I find I need to make an adjustment for timining, the points may no longer be at .020 on the "set" point on the cam or will it...I'm confused...

Re: 1975 Evinrude 9.9 - part 2

I cannot help on the play. I doubt you will get much play with the points cam but the timing plate may have some movement that may cause you some problems, but again I cannot provide much help here. Maybe someone else has some expertise.

The points do fire once they open. As I said, once they open (circuit goes "open") check to see if the timing marks are aligned. If they are, then move the cam until the point rocker block is at the "set" point and check the gap. It may not be 0.020". Whatever it is, note it and use it. The 0.020" is just the ball park number. The timing plate mark alignment is the gospel. Now if the timing mark on the flywheel is ahead or behind the timing mark on the timing plate, then you will need to change the gap so that those timing marks eventually line up, once the circuit opens. Now that being said, they usually tell you to set used points to 0.020" and new points to 0.022" to accomodate some initial wear that takes place on the rocker block on points. So err on the higher side of gaps with new points. I usually find that when my circuit just opens, my points are almost always set right at 0.020", so I just add 0.002" to that. It usually has the timing mark still inside of the mark but on the edge. Usually works great for me as I assume it moves itself into the middle of the marks, over time. I hope that makes sense.

Since you will be checking point gaps with a feeler guage, before you put the flywheel back on, it is a good idea to clean the points (even new points), as indicated above, as a very last step. Feeler guages can have oils and dirt on them that can get transferred to the points. Also, make sure your cam wick gets a drop of light oil (don't overdo it) or use the grease that comes with the tune up kit.

Re: 1975 Evinrude 9.9 - part 2

OK...that makes sense Optsy, it just took me a few reads to get it. I'll follow this procedure (including the cleaning) when I get the new points and see what happens. The adjustment to make if the timing marks don't line up is what I was confused about...From earlier testing, I know I have one cylinder that is off a tad but didn't know the fix so I went back to .020 at 'set'...maybe that's my issue?

Thanks!

Re: 1975 Evinrude 9.9 - part 2

The fix is difficult to explain, but basically if the points open before the flywheel hits the timing mark on the timing plate, then it is firing to soon and the point gap needs to be reduced and vice versa. I think that is the way it works but if you find it is the opposite I wouldn't call you a liar. I can't really remember, but the adjustment is either one way or the other.

When it is all said and done, setting them at 0.020" will usually get you close enough that any performance change may not be noticable if that gap is not perfect. I have found that adding the 0.002" to new points is usually advisable. Good luck.