properly time h with distributer

I changed my friends h to distributed ignition. What is the proper way to time it? Hopefully it can be done with a timing light. Do they advance as soon as they start?

Time it at idle. You can use a timing light, the pointer and notch are above the governor.

I time mine by ear.

Set engine wide open.
Advance until RPM increases, then decreases.
Retard until RPM increases, then decreases.
Set the distributor in the middle.

Much easier than messing with a light.

Well depending on the advance curve of the dist. and what the engine has in it. Myself i always set to full advance at wide open . Setting by ear so to speak is not the way to do it . But on theses old tractors one does not know if everything in the dist. is working like it is suppose to with out first having the dist put on a dist machine and see if the advance curve is doing it's thing and if is not then ya repair it so that it will work wright.

No it advances with increased RPM. Underneath the breaker plate are two springs and associated weights.

Unless you have a timing light that can be adjusted or a front pulley marked for maximum advance set timming with the engine not running. Jim N. give instructions on one way to do it in a recent post on timming a M tractor. Should find it in a post just a page or two back. After setting the initial timming unless you know what the distributor advance is or if its in good shape timming may not be as recomended at all RPM ranges after that though. To check on a tractor the pulley needs to be marked in the correct places or the adjustable timming light used.

I give a thumbs up to the tractor vet's answer, but have a few comments to add.

First off, the H should have an "A" symbol distributor (stamped into the distributor's flange). Other distributors will have a different advance curve.

I static time at 0 degrees. An early Owner's Manual will only have the procedure for a magneto. The procedure for a distributor is the same except for 2 details:
- rotate the distributor the opposite direction to advance the timing.
- there is no audible click, connect an ohmmeter to the points or turn the switch on and watch for a spark.

Once you have it static timed, use your timing light to verify proper advance. If you have the right distributor, the advance starts at about 400 RPM, so at idle you may see just a little advance. It should hit 19 at 800, 34 at 1,200 and finally reach 40 degrees at 1,600. If it doesn't come pretty close to those figures, either you have the wrong distributor or it isn't working right. Just checking for full advance at high speed is usually enough of a check.

If you do it "by ear" you won't have any idea whether it is working or not.

There was and advance change kit that were installed in some so you can not always go with the 40 degree If it will make about 27- 29 degrees wide open your good to go . And anything from TDC to plus 5 at ideal . I know at times i get to fussy , but that is just me .

I should have mentioned that. IH supplied the advance change kit along with the Fire Crater piston set. There was also a symbol "J" distributor, used in the Super H and others that limited the advance to 30 degrees.

Why do all the math, time it by ear.

If you time by ear to the middle of of rpm increase and rpm decrease you will always be over advanced on a higher compression engine. Detonation under load. With the old fuel burning, low comp engine, no big deal. Most fire cratered IH engines actually sound late with no load when timed properly. IH made 8, 16, 22, 25, 30 and 40 degree advance distributors in left hand rotation and all take different spring sets and shafts, same weights.

Remove the plugs (easier to roll engine by hand). With your thumb in the #1 plug hole, or over the free end of a garden hose chunk to fit into the plug hole about 2' long, use the fan blades to turn the engine, (if it is a new engine this might be too difficult to turn)The A raised up rear wheel with the tractor in high gear TA ahead can be used if a helper rotates the wheel forward. Turn it till a rush of air begins to come out of the hole (not past that point). Now put a plastic soda straw into #1 plug hole down against the piston (feel for it). As you now turn the engine farther, the plastic straw will come up and out. As it stops moving, the piston will be at TDC on compression. The marks on the pulley will be aligned with the pointer for TDC. If not, move the engine back or forth to align the marks. This is the position for static timing the distributor, and the rotor should be pointing to #1 plug wire (1342 Clockwise around the distributor, 1234 from front to rear). Using a test light on the lead at the side of the distributor, with the key on, the light will be off, or on depending on where the timing is currently set. To set it accurately, the top of the distributor should be turned away from the engine until the light is off. If it is already off, the distributor top should be turned toward the engine. The exact point of correct timing is that rascally spot where the light is sputtering to be on or off. Lock the distributor hold down clamps and all is well. To assure the centrifugal advance is working, a timing light can be used to assure that the timing advances according to the book to a total advance as specified. If not, there is something amiss with the advance mechanism in the distributor housing under the breaker plate. Best of luck. Jim