8n distributor lobe / weight assembly

Hey all - been a while - lots of "other stuff" has kept me away from tractorin' for a while.

I have a 52 sidemount 8n, all original 6 volt. I suddenly lost spark this past fall. I say "suddenly" although I had a few "no starts" last summer, that mysteriously solved themselves. I suspected a wet distributor.

I am getting no spark whatsoever at the plugs. Using a test light, I determined I'm getting juice to the coil, but not to the distributor. I swapped in a new coil with the same results.

I bought new points and a condenser. I went to install the new points and noticed there is a lot of slop in the lobe. By a lot, I mean there's enough movement that I can set the points, and the slop in the lobe will allow them to close again.

I've never seen a "good" lobe, so I have nothing to compare this one to, but to me, it looks like it is very worn. It almost looks completely round. The "lobes" are barely discernible from the rest of the cam.

Does this sound normal? Anybody have measurements on a good cam? I just saw the price of a replacement assembly and threw up in my mouth a little.

Thanks in advance!

Joe - who is fully expecting to get the "you idiot - why are you throwing parts at it?" tongue lashing that I most likely deserve.

Well if you look at say a small square box then figure if you took that box and made it as small as the distributor lobes you see pretty much what a lobe should be like. The lobes on the distributor almost never wear down but the shaft bushings do wear out and that would cause your problems

Have a peak at these lobes for comparison.

[i:5649850fc7]
Photo courtesy of JMOR[/i:5649850fc7]

[b:5649850fc7]"I'm getting juice to the coil, but not to the distributor. I swapped in a new coil with the same results."[/b:5649850fc7] Well, there's your problem :-}

Try these T/S steps to narrow it down a bit further:

Bypass the ignition switch. Did that help?

No?

Remove the cap/rotor. Turn motor to open the points - Turn the key on & place one probe of your volt meter to one side of the points & the other probe on the other side of the points. You should see battery voltage.

Still No Go?

Attach test light clip to ground. Put your tester probe on the nut where the wire enters the distributor. If the light comes on, you know the problem is inside the distributor somewhere.

If the light does not come on, put your probe on the + side of the coil. If still no light, move to the - side of the coil.

Keep going until you get a light on your tester. When you do, you know your problem is somewhere between that point and the next connection where there was no light.

Could be a bad wire, bad coil, points, or short inside the distributor. Inspect the delicate, copper strap inside the distributor that carries the current to the points. It frequently cracks but looks good except under close scrutiny.

(quoted from post at 16:28:47 03/06/13) Hey all - been a while - lots of "other stuff" has kept me away from tractorin' for a while.

I have a 52 sidemount 8n, all original 6 volt. I suddenly lost spark this past fall. I say "suddenly" although I had a few "no starts" last summer, that mysteriously solved themselves. I suspected a wet distributor.

I am getting no spark whatsoever at the plugs. Using a test light, I determined I'm getting juice to the coil, but not to the distributor. I swapped in a new coil with the same results.

I bought new points and a condenser. I went to install the new points and noticed there is a lot of slop in the lobe. By a lot, I mean there's enough movement that I can set the points, and the slop in the lobe will allow them to close again.

I've never seen a "good" lobe, so I have nothing to compare this one to, but to me, it looks like it is very worn. It almost looks completely round. The "lobes" are barely discernible from the rest of the cam.

Does this sound normal? Anybody have measurements on a good cam? I just saw the price of a replacement assembly and threw up in my mouth a little.

Thanks in advance!

Joe - who is fully expecting to get the "you idiot - why are you throwing parts at it?" tongue lashing that I most likely deserve.

Click to expand...

Across the flats = 0.720 inch
Across peaks =0.778 inch

good info so far.

follow that test lamp advice.

feedthru insulator can short.. and thus you won't 'show' voltage at that point as it is ground. disconnect wire to feed thru and see if coil shows power on both sides with key on.. etc..

if there is bushing wear.. you will need to fix that as well.

I just realized I never followed up on this post - sorry guys.

My problem had nothing to do with the lobe. I did the idiot thing and threw a bunch of parts at it - points, condenser, coil, and still nothing. Then I started over and traced my voltage again - and found the insulator on the inside of the distributor body was bad - it crumbled when I touched it. I replaced it with a 1/2 inch square of plastic from a chocolate syrup jug that happened to be right next to the tractor in the recycle bin. The tractor started right up and runs like a top.

Thanks again a for all of your help guys!

Joe