How Do you time a M ??

I did a search but and still not sure how to time my M. Here are the parts I do not understand.
" With the switch off; use an ohmmeter or self powered test light to verify the point opening instant"
[b:25f3f2508d]What wires do I hook the Ohmmeter to so I can see when the points open?[/b:25f3f2508d]
"Loosen the 2 distributor hold-down cap screws and rotate the body of the distributor in the direction of normal rotor travel until the points are closed (test light is on, ohmmeter reads very low ohms). Now rotate the distributor body backwards until the points JUST open; lock the cap screws and you are good to go."
[b:25f3f2508d]What screws are these? I do see 2 bolts that hold the whole assembly on. One bolt goes through a slotted hole on top and the screw on the bottom is just through a plain hole. This assembly does not turn at all, tried it. Are the cap screws hiding somewhere?.[/b:25f3f2508d]
"Late timing (too small of a gap or incorrect setting) will act like too rich carburetor problems."
[b:25f3f2508d]This sounds like my tractor. I have put in new plugs, hottest I can get in ACDelco and Champion but they still keep turning black fast no matter where I set the carb.[/b:25f3f2508d]
[b:25f3f2508d]
Any help would be really appericated. I hate my M running good but just not right.[/b:25f3f2508d]

Location of test leads:
With a test light, Hook one to ground and one to the terminal comming out of the side of the dist.
When light lights, the points are open.

The #1 cylinder must be at TDC This is at the end of the compression stroke, and the timing mark will be the last on in the series of marks.
Putting your thumb, or a whistle on a hose, in the spark plug hole makes this simple.

An ohm meter will be used when the ignition is off. hooked up the same as the light. When the reading goes to infinite ohms, the points are open, when reading near zero, they are closed.

The distributor body does turn in a limited arc Look it over again, it is there.

Once the static timing is right on. The advanced timing can be checked with a light. If it is not advancing, or advancing on startup, the advance mechanism may beed to be repaired. The springs weaken, they also break. The pivots can get worn, and rust can limit movement. It will not run well if it is not advancing, or advancing too soon out of spec.

After getting this sorted, the carb can be adjusted to correct the mixture. I would run it under load for a while to get the plugs clean enough to use. JimN

If you have distributor there is only 1 locking bolt and it is through a tab just behind distributor body and rotation is limited only by the wires. The 2 bolts are for timing magneto.

Do you have the main jet adjustment screw opened too far? You may need to close this to lean the carburetor some. It doesn't need to opened so far under light loads. It does need it if you're plowing or disking that will load the engine and the governor kicks in to maintain engine speed. Hal

Funny, all my distributors have 2 bolts through a tab/clamp.

You are right we never tightened the inside distributor clamp,found that one would hold it (most other distrbiturs I have seen only have one) and I had forgooten there was place for inside clamp. Looked at my tractors and on 3 out of 4 the inside clamp was gone.

One of my Ms only had one. Like that as long as Dad had been running it, Then one day I broke the bolt off and discovered the other hole. Got reamed by Dad for breaking it, but told him about the other hole. Went to the junk yard the next day for something else and found every Farmall with a dist had tw oclamps. Of course I was 12 back then, and didnt know any better.

Still not sure where that bolt for the tab is suppose to be that will let me turn the whole distributor. I do see 2 bolts at the end of the distributor itself where it bolts on the shaft but that all seems solid.
Gave the rest of the steps a try and everything seemed to be linned up where it should be. Had to clean the points up some and set them.
Took the M to an antique tractor pull today and came in second in the 5500 lb class. Lost by 2 feet to a Farmall 504 so the M is not running too bad.
Haven't checked the plugs yet, will do that tomorrow and see what they look like.
Thanks for the replies and help everybody.