I Will Defer...

Quote: "The so called "Lag Angle" is how much the static start (impulse) timings Lagsssss sss the advance run timing and its adjustable."

Got it, and thanks. So if the advance run timing is, say some number of degrees before top center, the start timing would be 35 degrees behind that?

I"m fairly sure of one thing; when hand cranking an engine, the timing MUST be such that the spark fires after top center. Otherwise, you"d have a very dangerous situation.

As I"ve noted, on engines with manual spark advance, the engine does indeed sputter and often die before you can advance the spark.

I think all that "Lag Angle" stuff is merely a way of lookin at it. I consider (and Wico does) its the angle the run time advance "lags" behind the impulse start time. i.e. if the lag angle is 35 degrees and she advance run times at 35 BTDC she would start/impulse right at TDC. I got to thinkin I agree with your notion in a way, its just that when you say 35 RETARD I think you meant she retards 35 BEHIND the run time advance NOT that she ever fires 35 AFTER TDC sooooo ooo lateeeee eeee, which is far to slow to ever start fer sure, although she could run poorly I reckon??

By The way me bein a retired engineer dont make me know more then anyone here whatsoever, it just means Im knee deep in theory, but as far as IHC mags I have like nooooo ooooo ooo experience and hope to learn n help others when I can. I give elctrical seminars at some of the national John Deere Shows and have written for some JD magazines but havent owned IHC for yearsssss sssss ss.

THanks for the great discussion I enjoy your informative posts and love this sparky chat as Im sure you see.

Take care now AB

John T

The impulse coupler causes retarding when the speed slows enough the engage the pawl. The degrees retarded is the angle traveled before the pawl releases. I do not remember amount of retard built in, but the mag runs with only two timing positions. Retarded at TDC and normal running position.

This is why IH wanted the mags replaced when using fire creater pistons. The distributors are variable with engine speed and ran more advance than the magneto normal timing at high idle.

John T