Clarification on setting points for magneto ignition.

[84toyota]

Hi all,
I have a 1971 Johnson 25hp outboard, that was dropping a cylinder. I've rebuilt the ignition with all new points, condensors, one new coil, new plug wires, and new spark plugs. Everything went well, and I get strong spark on each cylinder now. My question has to do with setting the points properly. I've found many references online which mention that the word "SET" is stamped on the cam for setting points. Mine didn't have that. It had the word "TOP" stamped on it, as well as a stamped logo that resembled the letter "M." I've seen a few references that mention setting the points based upon the flywheel key. Is that what I should be using, being I don't have the word "SET" on my cam? I wish I had a picture to help describe the problem, but I'm at work right now. I confirmed that I get good spark, but I hesitate to try to run it in a barrel yet, until I determine if I've adjusted the points at the proper part of the cam. I also have a 1972 evinrude 25hp parts motor, and it seems to be the same (the cam has no "SET" marking stamped on it).
Does anyone have a good picture that shows where the points rocker should be contacting the cam when setting points?

Thanks,
Ken

 

[jrs_diesel]

Re: Clarification on setting points for magneto ignition.

Use the part of the cam marked TOP, which is the high point on the cam. TOP = SET.

 

[kbait]

Re: Clarification on setting points for magneto ignition.

Just make sure that .020" is the widest gap attainable (pull the plugs and turn shaft clockwise to find the max. Set other pointset at same spot on cam), and you're good to go. If you're in the 'top' area, probably good. Or that 'm' deal. That's probably what it is.. M for magneto? Someone will chime in w/a PHD, and Doctorate - should be addressed as 'sir'.

 

[84toyota]

Re: Clarification on setting points for magneto ignition.



Here is a picture I found on ebay which shows my cam. What mark would I use when setting the points?

Ken

 

[kbait]

Re: Clarification on setting points for magneto ignition.

I'd find the max gap (in 'top' area, not that 'm') while rotating cam and go from there. I looked in the omc book, and it says 'find the high point on the cam by rotating'.. Good luck!

 

[JB]

Re: Clarification on setting points for magneto ignition.

I never bothered with looking for marks, 84Toy. I always adjusted the points so that at their widest opening they were .020" apart. On the other hand, I do not recognize the cam you show.

 

[84toyota]

Re: Clarification on setting points for magneto ignition.

Thanks guys... I set the points in the middle of the "Top" area, because it seemed to be the right spot (widest lobe on the cam). I'll look down the spark plug hole to verify. It was just throwing me for a loop because most of the info I found online kept referring to a "set" marking on the cam.

Ken

 

[Chinewalker]

Re: Clarification on setting points for magneto ignition.

That "M Deal" is actually the old OMC logo. It was an M with the O around it, designating Outboard Marine, I guess with the "Corporation" implied...

Easiest way to set the points - align the keyway (highest point on the cam) with the fiber rider of the points rocker. Gap to .020". Done.

 

[1946Zephyr]

Re: Clarification on setting points for magneto ignition.

Yep, that "Top" area is typically where you put the heel of the points, but there are times that you can find a higher spot, just like some here have stated.

 

[HighTrim]

Re: Clarification on setting points for magneto ignition.

Every since I bought timing fixtures off of F_R, I have never had to worry about this again.

I realize a timing fixture might not be practical for someone with 1 motor, that would only use it every couple years or so, but for collectors or mechanics it is a must have. In conjunction with an analog meter it is by far the best/easiest way to set the points. It ensures they fire exactly when they should, AND exactly 180 degrees apart, both of which are important. Using a 020 feeler gauge only gets you kinda close.

Again dont think that you need a fixture, but boy is it handy, especially when you do 50 to 100 ignitions a year!

 

[84toyota]

Re: Clarification on setting points for magneto ignition.

Every since I bought timing fixtures off of F_R, I have never had to worry about this again.

HighTrim - please excuse my ignorance - what is a timing fixture? I assume some sort of gadget. Do you have any pics? And where do you get one? How does it work?

Thanks,
Ken

 

[HighTrim]

Re: Clarification on setting points for magneto ignition.

This is F_R's page, I hope he doesnt mind that I post it. It explains it better than I could.

Instead of the light in the instructions I personally use an analog meter. I have set motors to 020, then used the fixture and set it exactly where it should be. There is usually a difference. Setting it to 020 just gets you close, usually close enough but not exact. The fixture gets you exact, and equally as important gets them to fire EXACTLY 180 degrees apart from one another.

http://i155.photobucket.com/albums/s311/frankr_photos/TimingFixtureInstructions.jpg

 

[kfa4303]

Re: Clarification on setting points for magneto ignition.

Here's a handy link. While F_R certainly has the best method, I'm a hack so I generally just look for the highest point on the cam and use that, which is usually around the "P" in TOP, but it varies slightly. Just as important, is that the points be equally adjusted even if they are slightly more/less than .020". Make sure they're nice and clean too. Good luck.


http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm (not your exact motor, but the same basic procedure)