Engine older Echo 40cc, I have never run it. Rotor on taper 7/16" shaft.
I have trimmed magnets off the rear, shortened the forward steel taper and reduced diameter to 2" thus far.
The rotor had factory cast marks T for TDC (verified), arrow for rotation direction, and a 'M' mark at 32 degrees BTDC.
My question: Would the 32 degrees indicated for points system be my guideline for setting the location for the magnet installation? Is there a time delay of some degrees in a point system that would not be present in say a CH IGN type ignition? Reading indicates that alot of these small engines operate with settings under 27 degrees.

Uncharted waters, one rotor, ask directions before drilling useless hole

I played with a McCulloch 32 with different timing settings. The engine wasn't real timing sensitive. but there was no improvement beyond 28 degrees as I remember.

Enjoy,

Jim

There are 2 coils in a points system..One generates electricity to go to the other, to be transformed into enough to jump the gap..The points are connected across the leads between the coils, with a capacitor across the points to supress the spark and keep the points from burning up...The flywheel magnets rotate past the soft iron core on the source coil, generating current..the current goes through the closed points until the points open at 28 degrees, letting the current go to the spark coil and making the spark If I remember right, this type of circuit is called a "squirrel cage" ...you can change the timing slightly by varying the gap between the points..If the points have a wide gap they won't open far enough before TDC, so the timing is retarded..If too close the timing will be advanced..Don't know how many degrees this works out to, but on a G23 it makes a difference......I don't see how there could be a time delay, unless the condensor acts as one....[8D]

Nope, when the points open, the spark happens. The condensor, besides "siphoning off" current when the points open so they don't arc and burn, also assists in the collapse of the electromagnetic field and makes a stronger spark. No delay. However, I think you mistyped that Ralph; wider points opening equals earlier timing; (more advance).

I've worked on some twin cylinder points ignition two strokes that have the timing set like this: You adjust both point gaps, then adjust one cylinder timing with a rotating stator plate. Then you adjust the timing of the other cylinder to match the first by fine adjusting that cylinder's point gap. It's amazing, (and aggravating), how a little point gap adjustment can change the timing quite a bit. Thank god for the newer electronic ignitions!!

AV8TOR

Thanks, I knew it was one way or the other...In my head I was seeing the gap between the rubbing block and cam instead of the points gap...However, I did say the spark happens when the points open[8D]

My experience with the older G23's is that they turn max RPM's with the points set at .011. Any narrower, erratic or no spark, too little dwell time. Any larger is too advanced, kicks like hell.

Ok, so back to Mike's question. Mike, can't you make your "rotor" adjustable by leaving out the key? Then you could rotate it and find the timing that the engine likes best.

AV8TOR

You can, the key does nothing, it's just a locator....[8D]

Good infomation on operating with points. I did not state my question clearly. The points are gone and not an option due to damaged coil, twisted off plug wire inside. Concern was magnet placement in the flywheel. Following is my plan, subject to change based on experience comments.

I have done some more measuring and calculating and think I have it solved. The 'M' reference mark had me concerned. I was not sure just where to drill the cut-down rotor/flywheel for installing the magnet for sensing.
The sensor has a effective linear movement range of about .5" along the rotational arc (.8" radius) of the magnet. It will be fixed at best location based on running. This is gives me an adjustment range of 0 to 32 BTDC. Q&D : {Circumference=(diameter x pi)} * {degrees of arc = timing degrees} / 360} .8"*2*3.1416*32= .5"

With the sensor at maximum CCW position, and the flywheel at 32 BTDC; I plan to mount magnet at the point on flywheel where it excites ign. This will give full range of adjustment Clockwise (.5) for adjustment.

I didn't check your math, but I think you are making a mistake. If you mount your magnet/rotor combo so that the spark occurs at 32 degrees, and you only have adjustment clockwise with the sensor, you've got a problem. Moving the sensor clockwise will only advance the timing. If you are already at 32 degrees, you won't be able to back it off. Moving the rotor clockwise would retard the timing, but moving the sensor clockwise will advance it. This is of course assuming you will be using standard counterclockwise rotation of the prop as you face it.

The reason we got carried away with the points thing was to address your question about a possible spark delay with points.

Hope this helps,
AV8TOR

You guys are discussing things all around the problem that has me perplexed. I removed the key so I could relocate the flywheel - after having relocated the position of the coil in front of the cylinder. The flywheel has three magnets and of course the coil has two locations of electrical contact. Can someone define the positioning of the flywheel relative to the two coil contacts at the time of ignition firing. Engine runs in the normal CCW direction.

Sides7

Side-7 I would say if you move the pick-up, say 90 degrees...then to keep the same timing...rotate the flywheel on the shaft the same 90 degrees. Should work I would think? Capt,n

av8tor1977 you are correct. I meant to correct post when I realized mistake and got sidetracked.
Should read 'sensor at maximum CW position, and the flywheel at 32 BTDC' Movement of sensor CCW reduces the timing advance.
Rotation is std CCW

Capt'n John
I'm sure your right about the move them both the same amount, BUUUUT I have long lost all reference re: the original location of the coil. John, this is the engine you and I have discussed before. (Zenoah 41.5 from RedMax blower) I had a neat adjustable bracket made to hold the coil. I'll post a PIC when I get a chance. It's running good, but I need a way to determine what the timing is set to - there may be more performance still available. Seems like there should be a specific relationship between magnets in flywheel and the 2 coil pickups at the time of firing?

Sides7

Well, here's a link, a really good one that explains it better than I can: www.foxvalleykart.com/timing1.html

In your case, I would use a timing light to make a mark on the case (and flywheel) to indicate the present timing. You could then experiment from there. If you want to know the timing in degrees, just use a degree wheel to check what degrees your mark actually indicates BTDC.

Good luck,
AV8TOR

Well, if you have a timing light, just point it at the flywheel while the engine is running, and you will see the where the magnets are in relation to the pickup when the plug fires.

Steve

If your mount you made is slotted ...move the pick-up to get max rpm, then check with timing light. also check for kickback on start-up. If you have too much advance...it will want to kick back when cranked. Be carefull ....big props hurt you bad. Good luck Capt,n Ps I have not finished my engine yet. Too many other things had to be done. I will get to it in mid winter ...for sure!