Fires but no start

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What I've done:

Primed oil pump
New D21 plugs gapped to .023
New distributor cap
Timed distributor rotor to magneto, lining up the matchmarks
Filed breaker points lightly and verified gap .013
Timed magneto
Cleaned starter contacts, checked flywheel and starter teeth (some wear on flywheel, no flat spots)
Rebuilt carburetor
Removed, cleaned, reinstalled manifold
Compression tested 80-90 psi all cylinders
Checked magneto ignition post for continuity, checked ok
Verified spark from coil to distributor and distributor to all plugs, firing in the correct order each time during hand cranking

I installed a new 6v battery and started to crank with the hood off to troubleshoot (still need to replace the fan and generator belts) so I've been using starter fluid instead of gas. I can get it to fire once, twice to several times during cranking but it won't catch and run on its own. Sometimes it's been firing really well once like it's going to start, but then the starter uncouples from the flywheel and no result. I've also tried hand-cranking with no results. I've tried combinations of choke/no choke and various throttle positions, seems like it fires best at higher throttle positions.

There was a period immediately after I retimed the magneto where I didn't have spark for two or three revolutions of the crank, but it's been sparking since.

Seems like I'm getting great suction from the intake, air, fuel, spark and compression, not sure what to check next. Would running on gas from a pony tank instead of starter fluid have different results?

[Clark Thompson]

the engine will not run on just starting fluid. It will need gas too. I would use a pony tank. I bet it fires up!

[lombard]

DID YOU USE NEW GASKET AND SHELLAC ON MANIFOLD AND CARBURETOR ??????

GOOD LUCK
LOMBARD

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New gasket on carburetor, new one on the way for the manifold (old one did not tear during removal). When the manifold was off I ran a die over the studs, a tap through the nuts and scraped the mating surface clean. Also used anti-seize during reassembly.

[Eugene]

Magneto's impulse coupling working?

Got an ignition timing problem.

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I cleaned and oiled the impulse coupling and I can hear it tripping twice per rotation of the hand crank (as the crank pulley notch passes the pointer and again on the opposite side of the crank pulley). Is there another way to verify function and check timing?

Edit: while reading on here I've found a variation in timing procedure. Both say to put the engine at 1 TDC, install magneto rotated against block. Then one says turn one revolution til I'm at the notch, another says two revolutions. Would this make a difference when I go to rotate the magneto listening for a snap?

[Rick Spivey]

Just to relate my own experiences, a couple times I swore I had the magneto correctly timed, but was still 180 out. It is apparently easy (for me) to do. On those occasions, I would get the occasional puff and cough, like you describe. Just for giggles, re-check the magneto timing in view of whether it might be 180 out or not.

[Eugene]

You can use a timing light with external battery to check the timing. It will take two people, one to crank over the engine and one to see if the flash occurs at the timing marks.

This will only tell you if your are firing at TDC for cylinder #1 or #4.

If the magneto is firing at TDC when cranking the engine, you will need to remove the magneto and rotate the drive lug 180 degrees.

[ricky racer]

What you describe sounds just like one I had that was 180 degrees out of time. Easy fix.

[Scrivet]

If it is 180 degrees out couldn't you just move all the spark plug wires two holes forward in the distributor cap?
Then if it runs PLEASE go back and rotate the mag 180 degrees and put the plug wires back in the normal spots.

[Eugene]

If it is 180 degrees out couldn't you just move all the spark plug wires two holes forward in the distributor cap?
Then if it runs PLEASE go back and rotate the mag 180 degrees and put the plug wires back in the normal spots.

Would work, easy check.

[Clip]

I think I'm confusing myself at several places. Went out and played with it again this morning trying several of the suggestions.

Eugene, my manual says on page 29, item 7: "To check timing, crank engine slowly until #1 TDC is reached. At this point, impulse coupling should just trip. Never time before TDC." I do hear the impulse coupling trip and I pulled the #1 plug to confirm spark on #1 TDC. I attempted to rotate the drive member on the impulse coupling backwards 180, but this put the rotor arm at #2 position so I continued to rotate backwards until back to #1 position.

Edit: think this is where I've gone wrong. Manual states the impulse coupling should trip, not fire on #1

I tried timing the magneto multiple times with the same result. I tried using both the cork and feeling for pressure, I've confirmed that I'm finding #1 TDC. Next, I confirm the governor slots are at ~2 and ~8 o'clock, lining up with the punch mark on the mounting surface for the magneto. Next, I look at the magneto in my hands and scratch my head.

I've turned the impulse coupling backwards til the distributor rotor is at the 12 o'clock position, pointing to the #1 terminal. At this point, the matchmark on the distributor rotor is at 6 o'clock, and the pinion matchmark is either at the 6 o'clock or 12 o'clock position.

The only other option I have to time 180 out is to align the TDC mark on the exhaust stroke or rotate the governor 180 until the slots are at 2 and 8 again, right?

[Clip]

If it is 180 degrees out couldn't you just move all the spark plug wires two holes forward in the distributor cap?
Then if it runs PLEASE go back and rotate the mag 180 degrees and put the plug wires back in the normal spots.

So rotating the mag 180 degrees means rotate the impulse coupling drive member until the distributor rotor arm is 180 out from initial, or mark on the drive pinion is 180 out from initial and replace the rotor arm in the #1 position?

[Scrivet]

180 degrees where the whole thing mounts to the governor. Two lugs that fit in the slots in the governor that look like an oversized compass needle. "North" points at about two o'clock looking at the governor opening. "South" points at about 8 o'clock. Rotate the needle and put the "North" needle in the "South" slot.

OR as a quick check.....
Move the plug wires two holes forward on the firing order (1-3-4-2). To avoid confusion lets call the distributor terminals A - B - C - H (hey it's an international OK ) with A being the one at about top right when sitting in the seat. B being below A, C to the left of B, and H above C and to the left of A.

H ... A

C ... B

Take the spark plug wire currently in A and move it to where C is at in the distributor cap and then put C where A came out of. Then take B and put it where H is and put H back where B was. You just rotated your firing order 180 degrees (assuming it is in the correct order to start with) and can see if the mag is 180 degrees out if the tractor starts and runs. If it does start and run put the wires back to their original spots and do the first paragraph above.

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Tried advancing the wires two positions, so instead of 1342 from the top, it was 4213. No change, back to proper order.

Tried rolling the impulse coupling backwards and timing 180, this put the rotor at the 2 position, resulting in firing when exhaust valves were open (flame out exhaust pipe). Tried rolling backwards another 180 putting the rotor at the 4 position, this resulted in flame out the intake. Returned to normal and still scratching my head. Don't think the timing is out 180.