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...maybe it's just me, or the dozens of standard and super motor points I have ... I've noticed in the past, even after cleaning them very well, sometimes I get flaky continuity readings when setting my point timing on an engine. For the most part, I can take any set of points I have out of the sealed package, and put a continuity meter across them, or even contacting directly to the face of one of the points contacts, and there is ZILCH continuity, which might be expected since you are supposed to solvent clean the preservative wax off them prior to use. If I clean them with various cleaners, anyone of these... acetone, chlorinated brake cleaner, alcohol, mineral spirits.... sometimes they work then, but not always ... then if I polish them using one of those rubber type Dremel polishing bits, they usually work well enough to set the timing on an engine. However, yesterday, I looked even closer, after doing all this cleaning and polishing, I took the continuity probe and slid it around the face of each of the points contacts, applying even pressure as I moved the probe .... half of the point contacts were rock solid for resistance and continuity, the other half, the continuity audible tone was cutting in and out depending where I was on the surface of the points contact. On the surface of those problem contacts, there was what appeared to be a stain, hardly even visible. My initial thought was, it must be oxidation or tarnishing of the contact surface (maybe these are silver plated?). So, I looked online for a home-brew chemistry method of removing this STUFF! I tried this and it worked incredibly well .... I filled a glass about 1/4 full, after heating the water for 1min in the microwave oven, I added several tsps of salt, and several tsps of baking soda, then about 4 sq-in of shredded Aluminum foil, stirred it up and dropped the McCulloch points in (there must be enough foil in there for the points to contact it). 15mins later, I took the points out, and dropped them in some heated distilled water, to remove salt and baking soda (leaving any trace of that behind cause corrosion). Visually, the stains on the contact points surface were GONE! and the passing the continuity probe over the surface gave a rock solid reading. I repeated this on several sets of points, same results. Basically in layman terms, the tarnish is moved from the points to the Aluminum foil, reversing the process that caused the tarnishing.

I would imagine though, that that the voltage across the points under normal operation is high enough that the observed stains on the points contact surface would not affect ignition performance, just make setting the timing a little more of a challenge, depending on the sensitivity of the continuity device one is using.

The cleaning method I tried might save a lot of time cleaning and polishing up these old points. Next I will try the chemistry method on a set of points right out of the package ... because I'm suspecting that the supposed preservative wax just isn't there anymore after these things sit around for 30-40 years! ... it may only be oxidation / tarnish that needs to be cleaned off. I'm report my findings later....

Jeff

I have had the same problem and seen the stain that you cant polish away with 1000 grit sand paper. I was on the grid at Kershaw this year and the engine fired and then cut off after getting the green. No fire. Replaced everything and no fire. Brand new set of points. No continuity on them even though it ran flawless in practice looking at the points and I see nothing wrong except the little round stain. Timing didnt change. Took them out and put them back in and everything was working again. Tossed them but couldnt explain why this occurred.

What would happen if you put a little DC voltage to that solution like they do to remove oxidized buildup from artifiact stuff they bring out of the ocean.

guys,
i looked this up for you.
the carbon tetrachloride is used by dry cleaners but i think though it may be banned.
this should help your points run better if you can find the stuff.
p.s. thanx to my daughter for retyping this as i couldn't paste it.
dave

"bulletin k125
models affected mc-5, mc-6, mc-10 mc-20
subject cleaning breaker points:

Complaints about early breaker point failure can be eliminated by changing the method of cleaning. The most popular method-that of drawing an emery stick or small card through the breaker points. The high spots will be cleaned, but more wax will be compressed into the low spots on the point surface. Later, when the collected was burns, it will have the same appearance as burned breaker points.

To remove was, saturate a small calling card in carbon tetrachloride and draw it between the beaker points. The carbon tetrachloride will dissolve all the wax and leave a clean breaker point surface.

WARNING
- carbon tetrachloride is toxic! keep in small
quantities when using and make sure room is
well-ventilated. Avoid inhaling fumes!

When installing a new breaker point assembly, place the assembly in a small can and pour in enough carbon tetrachloride to cover the points.shake the can.the sloshing of the carbon tetrachloride will remove the wax from the points."

hope this helps dave

They toook carbon technochloride out of brake cleaner years ago. You would still think that brake cleaner would clean it. I use acetone as well but that stain is always there

So now I know! I just experienced that same thing with point continuity! Brand new still in the sealed package from Mc, probably 40 years old too! I didn't trouble myself with all the cleaning, put em back in the lil container and found another good used set. Wish this post was three days older. lol Tom

... well that's a relief, I thought I was the only person having this problem!

Dave did a nice job posting the McCulloch method for cleaning that beeswax anti tarnish coating off a set of new points.... but use a different cleaning solvent, the International Agency for Research on Cancer (IARC) has classified carbon tetrachloride in Group 2B, possibly carcinogenic to humans. Probably not a good idea to hunt this stuff down to use it. As for using brake cleaners, the safe ones contain a lot of acetone and/or methanol .... the chlorinated brake cleaners are just as unhealthy and dangerous as Carbon Tetrachloride (I don't know how they can even sell those brake cleaners, especially since those chlorinated types destroy most rubber seals in brake calipers, I recently did some testing on this after a total brake failure on a kart!!!).

The problem with these points is that the beeswax or what is left of it, can be cleaned off with solvents and mild abrasion ... but these points are so old that the beeswax no longer is protecting them and they have significant tarnish. I think these are some type of Silver alloy contact points, usually the rivet contact buttons are made from a clad material, where a thin layer of Silver alloy is clad over a thick cheap base metal like copper, steel or whatever... Just sanding away at the points to get down into nice fresh Silver alloy, runs the risk of sanding through all of it, or leaving little behind for the wear life of the points. This is why I was looking at how to remove just the tarnish and not the good Silver alloy.

Last night I found a horribly tarnished set of NOS points, contacts were a very dark grey dull color, and tried the same home brew chemistry experiment on them, without any pre-cleaning at all. These points had zero continuity to start with, even probing the contact surfaces with pressure. After a 10min dunk in a cup of very hot water, salt, baking soda, and aluminum foil .... they didn't look clean and shinny, but nicer than they did going in .... they passed the continuity test with flying colors.

Just to get some confidence in this seemingly too simple chemistry deal ... I tossed in a couple tarnished pennies, 10 minutes later .... I pulled out pennies as shinny as any new penny you ever saw .... yes, this really works.

I'm thinking a good cleaning prep for NOS points would be to first clean with a safe solvent per the instructions Dave posted above, then do the chemistry cup dip (and rinse, all the salt and soda need to be removed from all surfaces, crevices etc...), then do another solvent cleaning and polishing. The points should end up with a nice shinny mirror finish, no stains, test 100% for continuity, and very little of the original Silver alloy will have been lost.

Jeff

Has anyone tried Tarn-x? Readily available at most grocery or drug stores. I use it occasionaly to remove tarnish from silver or silverplate articles. Never tried it on points.

I dip a strip of a white business card in laquer thinner and pull it thru a few times. Don't have any problems.

Now lets get a condenser checker!!!!!!

Now you will understand why i went the Electronic Ignition route in my hotsaws no more worries or no spark problems and very easy to install check my web site for more details.

Mc Bob.

After I posted last night I thought, "what about finger nail polish remover"? TL