Super-A points

Any thoughts about why the blocks on two sets of new points that ride on the cam lobes in my Delco distributor have melted?
It has a one-wire alternator. The hot wire from the ignition switch goes to the +post on the internally-ballasted brand-new coil, and the wire from the -post goes to the distributor. New points, condenser, plugs, rotor, cap, and coil. I'm mystified, and I don't have the cranial horsepower to figure it out.
 
Cheap China made points or ones form TSC can/will do that. I buy my points from O'Reilly's auto parts and there BW brand stuff most of the time and I have points on tractor that have been there for a decade or more and there still working just fine
 
More than a decade ago usable new points were easier to come by. I'll burnish my old ones as long as possible. Do they even sell Blue Streaks anymore? The last set of internet points I installed I had to operate on with a chain saw file and needle nosed pliers. Try NAPA and buy their best set.
 
Your new coil is isn't "internally ballasted", it is simply wound with enough turns of fine enough wire to limit current draw to a safe level,yet generate enough magnetism to induce a hot spark.

If you are able to measure the primary current, (ignition switch "ON", points closed) that will tell the story.

You are looking for around 3.5 Amps, give or take a little.

If the coil is "out of spec" (AKA a cheap china product), and you find the primary current much above about the 4 Amp level, it's gonna be tough on the points.

The other thing that will overheat points is leaving the ignition "ON" without the engine running.

Any chance you've forgotten to shut it off, or have some little gremlins that play on the tractor?

Also, quality points used to have phenolic rubbing blocks that could take more heat than simple plastic before deforming.

May be tough to find nowadays.
 
If you have an amp gauge on the tractor, you might see what it reads if you turn the ignition on and the points are closed. It should show approximately 4 amps. I've been getting ignition parts at the local NAPA store, their Echlin parts are better quality than I've gotten at other places. Here are their part numbers for Delco distributors:

ECH RR145 - Distributor Cap [Delco 811735]

ECH RR301 - Distributor Rotor [Delco 1905590, 1909008]

ECH RR164 - Distributor Dust Cover [Delco 1900119, 1912381, 1921312]

ECH CS763A - Points [Delco 1944374, 1911119]
ECH RR174 - Condenser [Delco 1869704, 1900272]

ECH IC7 - Ignition Coil [Delco 1115379]
 
1) Coil drawing too much current, as already mentioned.
2) Bad connection at points causing excessive heat:
- poor conductivity at contact points.
- poor ground where points are screwed into distributor.
3) Bad heat flow from points (lack of solid contact from points to distributor).
4) Bad batch of plastic for the rubbing blocks, may have to go through a whole case of points before it gets better (really long shot).
 
I've never had a problem like this before.
However, looking back, I first had a problem when I was helping my father-in-law mow his 10-acre corral, when my tractor stopped on the proverbial dime, running fine, then dead aa a coffin nail. Points were closed, but I was able to field-gap it back to .020, but to no avail- it wouldn't start. I didn't keep those points, or notice if they had also melted, but maybe this problem killed them also. I hadn't changed any of the electrical parts in a couple of years (I don't use this tractor very often), so I replaced all the electrical parts except the wires, and it started immediately, but then it died in 80 yards of mowing. This time I took a critical look at the points, but thought the plastic was bad and had disintegrated, and put in another set of points, and it died in about a hundred yards, so with an even more critical look at those two sets of points, they look more melted than worn. I've been stupid to throw parts at this problem, but then, in my father-in-law's 450, twice the leaf spring on his points had cracked and broken, killing his engine twice, so I was only thinking that, man, stuff is getting awful cheap nowadays.
Now that this was mentioned, you're right Bob- the coil did not say it had an internal ballast- it said I didn't need an external one.
But I will do the suggested electrical testing- I have a top-of-the-line whoop-de-doo $25 multi-meter, but it ought to show the numbers relatively close. All I knew to test on the old one was volts-in and volts-out with the switch on, and both 12.4 volts. I did notice today that the wire from the coil to the distributor has some exposed wire- maybe it has internal corrosion that is increasing the resistance. Maybe the new coil (Mexico) is a piece of junk and I didn't need to replace it, but I didn't know how to test a coil.
First thing is to get it to the house- it's dead out in the middle of my field. No chance for new points until Monday, but I need to figure what's up with the electricity first.
Can you tell me where I'm to put the leads of my meter to test the amperage- negative side of the coil to ground? Or further into the distributor?
Thanks.
 
"I did notice today that the wire from the coil to the distributor has some exposed wire- maybe it has internal corrosion that is increasing the resistance."

That is possible. However, increasing resistance will decrease the current so that is not your problem. However, since one wire is bare, suspect others to be cracked, stiff, and bare also. It is obvious what a bare wire against any part of tractor frame will do. Time for some new wiring.

"Can you tell me where I'm to put the leads of my meter to test the amperage- negative side of the coil to ground? Or further into the distributor?"

Amperage is current flow through the wire. To test it, connect your leads to 10 amp connection on your meter, and set scale to 10 amp range. Remove wire from + connection on coil and connect red probe of meter to the wire and black probe to + on the coil. With switch on and points closed you can read the current on the meter.

Check your coil. A direct 12 volt "no resistor required" coil should read 3 ohms from plus to minus on coil. 6 volt coil or 12 volt with resistor required should read 1 1/2 ohms. I would verify the 3 ohms and eliminate possibility coil is mislabeled. Short meter probes together and read the resistance. Then measure across + to - and subtract shorted probe reading to give resistance of coil primary (+ to -)
 

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