Timing the iginition on a Farmall H - two marks on pulley

Setting the distributor on a Farmall H. When I brought the number one cylinder up to top dead center on the compression stroke the steel pointer lines up with the marks (notches) on the crankshaft pulley. That is just the problem - there are two notches on the pulley. They must be about 1/2 inch apart or so (can't remember exactly). Which one do I use to set the timing with the engine not running??? Why are there two - what is the purpose of the other notch? Thanks.

It should be the first mark according to the rotation.

The first mark is the timing for advance, the second is TDC. there is no need for marks aster TDC. Jim

The second mark is to set magneto timing. It retards the ignition timing so the engine doesnt kick back when hand cranking. Also, if you look about half way further around the pulley, you will see a mark by itself. If you line that up with the timing pointer, then look up in the weep hole in the bottom of the bell housing, you will see the grease zerk in the flywheel to grease the clutch pilot bearing.

See correct Above. Jim

correction......had to pull my h and m owners manuals. the first mark is tdc. my mistake. the impulse coupler should just trip when the piston hits tdc at the pointer.

I stand corrected sir.

Thanks Jim

First mark is tdc. Second one is 5 degrees after and is for use with a magneto to time the impulse. Direct from mother harvester years ago and I have had enough H & M's apart to verify first one is top dead center.

First on most H's or M's there are 3 marks on that pulley. The mark all by itself when aligned with the pointer allows one to grease the pilot bearing from underneath the tractor. That is all it is used for.

Of the 2 marks together: think of that 2nd mark as only a visual indicator only in most cases and at minimum it keeps you from confusing it with that other stand alone mark which you would easily do if it were not there. If you have a distributor in your tractor then no chance you will use that 2nd mark for anything other than as a visual indicator. If you have a magneto then I guess you could use that 2nd mark but it likely depends on the procedure you are following. The IT manual does not use that 2nd mark. But I have heard of people purposely retarding the timing a bit if you plan to hand crank so you do not get a broken arm from engine kickback if timed too aggressively.

The first mark of the 2 marks that are close together is #1 cylinder at TDC.

If you plan to time your tractor without the engine running then these are all the marks that you need and you can follow IT manual procedure or IH static procedure accordingly.

[u:3e766ad6ef]Unfortunately, if you want to time your engine running then you will need to account for the advance in the distributor (if you have a distributor) by adding you own timing mark with either a white paint pen or liquid paper whiteout correction fluid that typists use works too. [/u:3e766ad6ef]

To do this you need to some math and have a flexible tape measure that you can use to follow the perimeter circumference of the pulley.

Most H's have a crank pulley that measures 6.5 inches in diameter.

For a desired 40 degrees setting on a Farmall h: measure 2.269 inches (or 2 and 9/32 inches) by following the perimeter of the pulley with a flexible tape measure in the advanced direction from TDC mark and add your mark with a paint pen. Use a timing light and align with your added mark with engine running.

For your own custom degree calculation on a Farmall h which you may need to do if you have high compression pistons then use the following formula:
6.5 x 3.1415 x (your desired degree) / 360 = value in inches from TDC mark for you to place your mark

Most M's have a crank pulley that measures 7.49 inches in diameter.

For 22 degrees on a Farmall M: 1.438 inches (or 1 and 7/16 inches) advanced from TDC mark make your mark with paint pen.

For 30 degrees on a Farmall M: 1.960 inches (or 2 inches).

For 40 degrees on a Farmall M: 2.614 iches (or 2 and 5/8 inches).

For your own custom degree setting on a Farmall M use this formula again which you may need to do if you have high compression pistons: 7.49 x 3.1415 x (your desired degree setting) / 360 = value in inches for you to place your mark.

Note1: Timing should be done at Wide Open throttle on the Farmalls when using a timing light.

Note2: Ideally it is a good idea to verify your wide open throttle setting is close with a tachometer (I use a hand handheld and measure off the PTO shaft to set both idle and WOT governor settings). At unloaded WOT on a Farmall H or M you should be close to 600 rpm on PTO shaft.

Some Farmall M specs
Low idle: Engine - 425; PTO - 158
Rated speed: 1450; PTO 540
High idle: 1595; PTO 594

Pete you should know so I'm not saying you are wrong. Like a few others I always wondered what the correct answer was before when other posts said time to the retard mark. I didn't know the correct answer and still don't so I never questioned before. Would like to find out more though. I have some operators manuals starting in 1940 and a few others along the way up to a 300 equipped with a magneto. They all say the impulse should trip at TDC. Did IH send out a bulletin on the timing and never change the operators or repair manuals up into the middle fifties? Latter tractors when equipped with a magneto didn't have the retard mark on the pulley.

I don't remember just where I got the information. Might have been at service training from one of the older IH "block men" like they called them back then. But anyway, the explanation is for safety first off and second, the magneto's advance was closer to 40 degrees so setting it 5 after gave you the recommended 35 degree advance. As you well know, a few degrees one way or the other on those old low comp engines didn't amount to squat. When we put power packs in , well, things got to be fussier. One other thing that has never been mentioned is if crankshaft has been ground, sometimes the grinder cheats a little to get the best overall journal and that can change the top dead center a bit. The local machine shop explained that to me one day as I had found an 806 diesel that the flywheel tdc mark was off 8 degrees and it had been reground previously. I used a dial indicator on piston when head was off to determine that. That really threw me as I hadn't run into that before or maybe just never checked the marks that close. I would not want to hand crank an engine timed to fire at top dead center. It could go either direction really easy.

I have often thought about how to time my H with a timing light. I will be trying this.
Thank you. Mark

(quoted from post at 04:46:19 12/16/13) I have often thought about how to time my H with a timing light. I will be trying this.
Thank you. Mark

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You are welcome. Actually much of the info in my long post was pilfered from the archives of posts by Pete23 and Owen Aaland. All I did was take lots of their tidbits of info contained in numerous individual posts. With those tidbits of info then I had enough info to backwards create the mathematical equation as I had no way to accurately measure that pulley.

Personally, I do not like a static timing procedure. I want to set it with engine running at WOT as that is where everything needs to be correct on a working tractor that is going to be worked hard.

Most stock pistons will require the 40 degree advance calculation. However if you have firecrater or some other dome pistions then the timing needs to be adjusted more conservatively to keep from melting things on a worker. Usually those kits came with a recommendation on what to set the timing at and some kits even came with different springs to put in the disributor to alter the advance curve.

I always check to see if the advance is working by having someone throttle it down while I watch with the timing light and then throttle it back up. Reallt though I only worry about having the timing set properly at WOT for the pistons being used.

Much less chance you will destroy anything if you use a timing light and do everything properly compared to how it could be all wrong if you use the static procedure outlined in the books and have high dome pistons with stock springs in the distributor. If you follow static procedure you will end up with 40 degrees of timing on a non-stock engine that should have only 22 degrees.

My outlined method sets the timing with it full advanced so your are covering your worst case scenario.