Compression?

[Jimerjam]

Thank you very much, this is very helpful

[Jimerjam]

So, I finally was able to reassemble the mag, a gasket broke and then I had to find a lost screw, problem is I don't know how much the engine moved during it's absence, by the looks of things it can only fit in two ways, how do I tell what one is correct?

[Jim Becker]

. . . by the looks of things it can only fit in two ways, how do I tell what one is correct?

Actually, four ways. Turn the engine over until the number 1 cylinder is coming up on compression and continue until the notch in the front pulley lines up with the timing pointer. Then rotate the magneto backwards until lthe rotor points towards the number one spark plug wire's position in the cap. Bolt it on and set the timing.

If you need help with "number 1 cylinder is coming up on compression" or "set the timing" you can search for the numerous posts on the subjects or come back and ask for details.

[Glen]

Hi,
You didn't say if you took just the cover over the points off, or the whole magneto off the engine.

If you just removed the cover, and turned the rotor or engine, and don't know where to turn it, you should turn the engine to number 1 cylinder Top Dead Center, or TDC.
That is where to begin when trying to set the timing.

Below is a page from the 1947 Cub owner's manual telling how to time the magneto to the engine, if you removed the magneto.
It also tells how to find number 1 cylinder TDC, in paragraph 2.
If you didn't remove the magneto from the engine, and only want to put the cover on it, use only paragraph 2 and turn the engine to TDC.

http://farmallcub.com/rudi_cub/www.clea ... age-32.jpg

After finding TDC, turn the rotor so it is pointing about straight up, which is where number 1 cylinder's spark plug wire originally goes.
Put the cover on and try it, it should run.

[inairam]

There is a video on setting the timing for a mag https://youtu.be/QqucExhxXdE. It gives a good overview

[Jimerjam]

I used o borescope to align the number one piston to top dead center, attached magneto. I tried the test where you position the magneto output to ground and see if you get a spark at one 1/4 inch. Nothing, not a single spark no matter how close it was. I have no idea what is going on anymore

[Jimerjam]

Double checked my manual and I got the plug wiring wrong, it now turns and occasionally pops off. Next thin I will be doing is buying new plugs

[tst]

it is out of time

[Don McCombs]

I used o borescope to align the number one piston to top dead center, attached magneto. I tried the test where you position the magneto output to ground and see if you get a spark at one 1/4 inch. Nothing, not a single spark no matter how close it was. I have no idea what is going on anymore

Top dead center on the compression stroke. It does it once on the exhaust stroke, too.

[Jimerjam]

And yes, I made sure it was the compression stroke by checking the valves

[Eugene]

I used o borescope to align the number one piston to top dead center, attached magneto. I tried the test where you position the magneto output to ground and see if you get a spark at one 1/4 inch. Nothing, not a single spark no matter how close it was.

Magneto fault if you are getting no spark.

[Glen]

Hi,
If you replaced the points and condenser and the magneto has little spark, the coil may be weak, and need replacing.
It is common that the old coils quit on Cub magnetos.
Sometimes the coil makes a weak spark.
Sometimes the coil quits when the engine is hot, but works again when the engine is cool.
Sometimes the coil quits completely.

The coil is under the cover on top of the magneto.

Below is a listing for it at TM Tractor.

http://www.tmtractor.com/new/el/713fp.htm

There is a rectangular bar through the center of the coil, keep it and reuse it in the new coil.
You have to remove the cover over the points to replace the coil, to connect the small wire in the pic of the coil above.

They have said on here be sure to give the spark the magneto produces somewhere to ground to, it can damage the coil to make the magneto snap, with no spark plug wire going to ground.

[Jimerjam]

I retested the magneto, arced yellow occasionally. I think The problem is either the contact or the coil, I don't know what one it is

[staninlowerAL]

You didn't explain how you tested the coil but JMHO you're probably looking at a new coil and a general servicing overhaul of the magneto. Check out the service manual GSS 1012 at the top left corner of this page at Quick Links tab. There's more to it than just replacing the coil. In your earlier posts you referenced some battery issues. FYI, the magneto does not use any battery power to function but provides ignition power separately from the battery.

[Jimerjam]

You didn't explain how you tested the coil but JMHO you're probably looking at a new coil and a general servicing overhaul of the magneto. Check out the service manual GSS 1012 at the top left corner of this page at Quick Links tab. There's more to it than just replacing the coil. In your earlier posts you referenced some battery issues. FYI, the magneto does not use any battery power to function but provides ignition power separately from the battery.

Yeah I know. Either way I widened the spark gap, and no spark. Not even a weak one