Ignition timing detail question - 1956 Johnson 5.5 HP CD-13A

[pfrulas]

Hi guys, im in the process of tunning and restoring a CD-13A motor, I just rebuilt the igntion system but Im having the weirdest problem, while tunning the points. I use the feeler gauge to space the points .020 apart while the rubbing arm is on the high point of the cam. Then I use a continuity reading to fine tune, with the flywheel closed and this is where things go weird.

The .020 see to be way off, but as I fine tune the adjusting screw, Im able to time the closing of the circuit between the marks on the magneto.... but , once the points are touching, the keep touching for almost half a turn of the flywheel.

My first question is, for how long are the points supposed to be touching (making contact that is)? is it normal that they are touching for half a turn.

Second question is my assumption. The cam has a mark for the top, which is where we gap to 020. is it safe to assume then, that the opposit points should be touching at tha same moment? Im guessing both cylinders are 180 Degrees apart, which means I could tune one point 020 and the opposit one to just touch ?

This is how the ignition mangeto looks so far

View attachment OykbN6yYDpHlPbOzgwif6kidjQBJnrFSny0Mie8Myjf7RGtYafDQ1A6qsqAcVYxL2hx-fMETsIiBNLzhV9YpxJm8V-oRxyCi5hA3

Ill upload a video that shows the issue as well ... thanks !

http://forums.iboats.com/forum/engi...956-johnson-5-5hp-cd-13a-tunning#post10373306

 

[tomhath]

It should fire when the points open. They are closed most of the rotation.

 

[racerone]

You can find videos using a timing fixture to set the points with a meter.--------Fact ,-the fixture is nothing but a " dummy flywheel" so you can use your flywheel.-----------Lock the magneto plate so it does not turn.--------Does NOT mater if it is at idle / full throttle or inbetween.---------Rotate flywheel till timing mark is inbetween the 2 vertical marks on the mag plate.---Check which cylinder is near TDC.-----Lift off the flywheel and set the points.-------Repeat for the other cylinder.

 

[pfrulas]

Hi raceron, sounds like a good approach, so basically you physical position the flywheel mark in between the 2 vertical marks on the plate. You remove the flywheel and then adjust the points to be touching, fix, and repeat for the second set?

Is there anyway to "test" if the timing is correct other than checking for a spark with the sparkplug?

 

[pfrulas]

tomhath, so its ok if the points close when the timing mark is in between the 2 vertical marks on the mag plate ... and stay "closed" ... until the other points touch ? I'll do some testing and share the video and results ! thanks !

 

[tomhath]

I'd just set the points to .020 and see how it runs. The small motors aren't all that fussy.

 

[RCO]

The "TOP" mark on the points cam is not where the points are gapped, it is just showing which side of the cam faces up. The high/set point on that motor should be even with the keyway. The .020 gap setting is a best guess type thing where the motor will run fairly well. I assume you are using a multimeter to set the points? That is very tough with a digital meter. Back in the old days points would be fine tuned with a buzz box, listening for the tone to change when the circuit starts to open/close. The two cylinders are completely independent of each other, so it makes no difference what one side is doing compared to the other as long as they both fire at the correct time.

 

[Crosbyman]

http://www.youtube.com/watch?v=ga1Cjymj6ms&feature=youtu.be

​small analog meters are just 10$ .... even a plain old battery and bulb or LED should do to detect open/close across the points
​but Racerone's method sound's like brilliant reverse engenering and I will give it a try on my next 9.5 challenge resting in the shed.

 

[pfrulas]

Hey guys ! Im happy to report, that I have a SPARK ! RCO's comment was a revelation, I was gapping the points using using an indicaion next to the "TOP" mark on the cam. Before taking the reverse engineering approach suggested by racerone, I tried the simple 020 using the key in flywheel key as reference, I cleaned the points and boom. Beautiful blue spark.

I was wondering if I should try some fine tunning (I do have an analog multimeter, in fact I have an analog and a digital but I love to see that needle go left and right !) and, being a believer on the "old days" I built a small lighting circuit with some batteries and an LED to test for continuity, since this method is suggested in the manual. However, do you think its worth any further tunning ? I have a nice blue spark !

Check out my Homemade plug tester with an old spark !


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[Crosbyman]

I have used just SET markings to set point at 20 before I did some with the analog meter , all worked great after give it a try with the meter just for practice.

 

[Crosbyman]

I have used just SET markings to set point at 20 before I did some with the analog meter , all worked great after give it a try with the meter just for practice.

nice spark...

 

[pfrulas]

I wanted to go back and do the setting with the meter - light now that I?ve set the points, just to fine tune it , however, the spark looks good and I want to move on to cleaning the cylinders, changing the oil in the LU and cleaning the carburetor. Lots to do ! thanks for the help !