Farmall A HAND CRANK KICK BACK

Thank you,
MJF

Unless the impulse is sticking it will not kick. As other have said, only pull up on the crank with your fingers only and a kick will not hurt you bad.

If the tractor does not run well bu truns better with the mag set earlier the mag needs to be repaired.

I don't have the book here in front of me, but If memory serves, it should fire about 35 degrees AFTER TDC at hand cranking speed and change to fire at TDC when the magneto achieves something like 150 RPM. That is what he magneto impulse does for you.

Now that is from memory, gene bender can give you the exact specifications on it.

PS Im of the opinion that 35 BTDC is too much advance and I prefer more like 25 at typical antique tractor engine RPM's on gasoline. I think the 35 degree advance was more like for lower grade slower burning fuels/distillates as opposed to gasoline where I believe 25 degrees of advamce is plenty

Any agreement or disagreement?????

Again Im NOT an IHC Mag man but have experience with plenty others, good topic GREAT discussion..... ...

John T

A tractor or other vehicle which is hand cranked with the timing closer to top dead center does become easier to start.

It also becomes more deadly. If the timing ever fires before TDC while hand cranking, you will almost always get a kickback.

The chart in the IH-8 manual clearly shows the H4 magneto "with serial numbers 1353301 and up" is supposed to have a lag angle of 35 degrees. Others have a lag angle of 7 deg.

I don"t know squat about IH mags; but I do notice a similarity between what the manual calls "lag angle" and Red Dave"s description of what the impulse does.

In other words, when you set the timing STATICALLY, the impulse DOES trip at TDC. But at hand cranking speed it automatically retards the timing to 35 degrees after top center, pushing up to where it needs to be (before top center) at engine speeds.

Right, Dave?

AT HAND CRANK RPM AND AT ANYYYYY YYYYY RPM LESS THAT 150 TO 250 OR SO (i.e. while starting) the Impulse trips (according to where its adjusted of course) which should be somewhere around dead TDC....

Then (how Wicos perform at least) the timing advances to the 25 to 35 BTDC ONLY AFTER the 150 to 250 RPM range when the impulse becomes disabled i.e. she snaps/impulses (depending on where its adjusted) to fire near TDC at hand crank RPM and CONTINUES TO FIRE THEN UNTIL AFTERRRRR RRR 150 TO 250 RPM when the impulse is disabled PERIOD ..... ..... ..WITH NO 25 TO 35 "RETARD" SOMEWHERE IN BETWEEN.

I just fail to see how or why they would somehow snap at the adjusted point (near TDC) when hand cranking,,,,, ,,,,, ,,,,, ,,,,, ,,,,, but then somehow change to 25 to 35 RETARD,,,,, ,,,,, ,,,,, ,,,,, ,,,,, ,,,,, ,,,, and then over 150 to 250 RPM change again to 25 to 35 BTDC ADVANCE?????

On the Wico Mags the reason n how they advance over 250 RPM is simply cuz centrifugal force causes the engage dogs to suck in whereby the spring wind n trip (impulse) mechanism IS DISABLED That way they fire at the static starting timing (which one adjusts to near TDC) while cranking and up until 250 RPM, buttttt tt above that since the engage dogs dont extend they fire at the advanced run timing which is a function of the drive cup (like if its a 25 or 35 BTDC cup) plus the dynamic rotational mag timing adjustment.

The so called "Lag Angle" is how much the static start (impulse) timings Lagsssss sss the advance run timing and its adjustable. On the Wico Mags (and I would guess IHC are the same) theres ONLY TWO times, the static start (Impulse) timing and the advance run timing over 250 RPM with no other 25 to 25 RETARD at some time after hand cranking but before 150 to 250 RPM ????? ????? ??

HOPE THE IHC MAG EXPERTS CAN CONFIRM OR SHOOT THIS DOWN LOL Do they have ONLY a static start time (impulse) and an advance run time over 150 to 250 RPM

orrrrr rrrrr

Do they fire at TDC,,,, then Retard to 25 to 35 AFTER TDC,,,,, ,,,then go back to 25 to 35 BTDC Advance

My bets on the former i.e. ONLY a start impulse static timing and an advance run timing over 150 to 250 RPM PERIOD?????

God Bless yall, take care SPRING IS CLOSE BYYYYY YYYYY

Will an IHC Mag expert PLEASE answer all this ??? makin me curious

John T in Indiana

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

This is a big reason why it is relatively safe to crank a tractor with a conventional Kettering system that is also equipped with centrifugal advance, such as other Farmalls and many John Deers. If functioning properly, the centrifugal advance usually assures the spark is retarded past TDC for starting.

On Model T, where the spark advance was manually set by a lever on the steering column, many a child and other non-driver was taught to get "get that spark lever down!" on command once the engine fired.

That way the person cranking could start with the spark well retarded, which often made the engine splutter and miss and only run for few critcal seconds but which assured SAFE cranking.

(And, there were even a few ancient cars, like some Packards, where once the engine is warmed up one has only to flick the spark control through its range to start the engine WITHOUT cranking!)

So, check the mag for correct operation. In the meantime, be VERY careful cranking this tractor!

Henry Leland, head man at Cadillac, commissioned the first modern self-starting system from Charles Kettering, because a close friend of Leland's was killed cranking a Cadillac.

Never wrap your thumb around a crank. (Or a steering wheel when going cross-rows!)

Always pull UP on the crank, standing slightly off to the side.

And, as others have said, ALWAYS have the spark retarded below top dead center!

Bob's advice below is right on the money.

Check the timing and make sure the impulse is working right.

I'm curious if others find this true???

John T in Indiana

Apparently, you have "mag" ignition.

The timing should be set no earlier than TDC, or you risk a "kicback"

With the "kill switch" "OFF", slowly bring the engine up on #1 TDC. The spark occurs when you hear the mag's impulse "trip".

The timing marks can be viewed by removing the little cover under the flywheel, and looking UP at them.

See where the timing is set... since it doesn't always "kick", the problem COULD be related to a sticky, gummy "impulse" in the mag, if the timing IS correct.