What causes dirty ignition points?

Pat Martone

Pat Martone

Senior Member
I would like to know what causes dirty points?

Also, how often should they be checked and cleaned?

I discovered dirty points when timing my engine via the light bulb procedure outlined by Les Andrews' Vol 1. At first I could not get the light to go out when the points were closed! Upon inpecting the points, the contact point attached to the points arm was dirty and had some scarring on it. After removing and cleaning the points with fine sand paper, the timing procedure worked fine.

I welcome similar stories and advice.

Thank you.
 
It caused by arcing as the points open ( electrons moving from 1 pole to another )
it is kept to minimum by the condenser
if your get a build up on 1 side of the contacts your condenser is on its way out
 
Ignition contact points like to be kept dry and free of oil that can accumulate from over oiling the upper distributor bushing or too much lube on the rubbing block. This burns and becomes an insulator between the contacts. Also leaving the ignition switch on with the points closed will cause them to burn and oxidize.

Chet
 
The points in my Bendix magnetos would sometimes not transfer the voltage when the Continental O-470 was cranked over on humid mornings. I theorized that the condensation with the high voltage would cause the contacts to glaze over and become an insulator. She wouldn't even try and start until the points were filed and dry.
 
Thanks for all of the constructive comments and advice.

The next time I suspect an electrical problem (which we sometimes think is a fuel problem), I will immediately clean my points first.
 
Rather than immediately jump on the points the next time you have a problem, look at the ammeter when you are cranking the engine. If it's slightly moving up and down as you crank the engine, the points are working. Notice this when the engine is working normally and you'll know what to expect when you have your problem. If it's NOT moving up and down when cranking, the points are the first place to look.

I watch my ammeter when I turn on the key. If the points are closed, you'll see the meter drop.

sd
 
Hi Pat,

Good information above.

Also as mentioned, even with a well balanced distributor ignition system, if left unattended in very humid climates, (especially in the fall & spring with cool nights & warm days), with moisture condensation, points can oxidize just like ferrous metal will rust, copper can slowly oxidize & can turn green, & zinc will form an off white coating.

Contact point oxidation is prevalent with marine engines stored on or near water in very humid climates.

If one uses a "Point File", & only a "Point File" this tool if carefully stored & used, can not only clean oxidation off of points, but with this tool a good set of points should still be going strong after 80 years or so.

My Model B distributor points I was told by my mechanic Uncle born 1905 are original -- presently have them on my B distributor on my Model A engine.

Hope this helps.
 
H. L. Chauvin said:
Hi Pat,

Good information above.

Also as mentioned, even with a well balanced distributor ignition system, if left unattended in very humid climates, (especially in the fall & spring with cool nights & warm days), with moisture condensation, points can oxidize just like ferrous metal will rust, copper can slowly oxidize & can turn green, & zinc will form an off white coating.

Contact point oxidation is prevalent with marine engines stored on or near water in very humid climates.

If one uses a "Point File", & only a "Point File" this tool if carefully stored & used, can not only clean oxidation off of points, but with this tool a good set of points should still be going strong after 80 years or so.

My Model B distributor points I was told by my mechanic Uncle born 1905 are original -- presently have them on my B distributor on my Model A engine.

Hope this helps.
Click to expand...

HL, I read in one of the original service materials that points should be dressed with a stone and not a file....is that not the case? I actually think one of the KR Wilson tools in their catalog shows a little tool to clean up points and it shows a stone, not a file.
 
If your points are wearing out very quickly, check the coil. Under use the points should show some wear on the rubbing block and contacts Which will look a little dull if operating correctly, but if the contacts go out in only a few thousand miles, the coil has shorted turns in the primary. Found this out on a VW years ago that had to have new points every 3k miles until installed a capacitive discharge ignition system and coil finally quit. Points lasted forever with the capacitive discharge ignition system.
 
Hi eric,

Per your reply #10, points are made with soft, non-ferrous metal & what you read is correct about not using just any "file" to clean ignition points.

If you ever clean your points with a regular high carbon steel "file", this particular "file" can cut through & remove this soft point metal with several swipes.

The 1930's were not void of uninformed mechanics; hence, with money so tight during Depression, this caution was written for not using said very sharp standard blacksmith's "files".

Now, if you ever buy an ignition "Point File" & try to remove all of the soft point metal from your points in a few weeks, please first go to Home Depot to buy a lantern with about 5 gallons of kerosene & an alarm clock; next, stop at a grocery store to buy about 3 weeks worth of groceries & bottled water; & on your way back, go to NAPA to buy a real ignition "Point File".

Then set up a schedule with your alarm clock & start filing away on your points with an ignition "Point File".

Then call us in a few weeks to let us know how much metal was removed from your points.

On the other hand with stones, there are different types of stones where most can sharpen Solingen steel knives; however, if you try to sharpen a good hard steel knife with an ignition "Point File", please buy at least 165 "Point Files" at NAPA & buy a full years supplies of groceries & kerosene.

Really not trying to be funny or rude in any sense or in any way, but in a humorous manner of instructions, I find that if one actually buys an ignition "Point File", & a regular "file" & tries both on a set of points, one will never forget that there is a remarkable difference between a blacksmith's "file" & that which is known as an ignition "Point File".

With sincere respect, just humbly hope this helps.
 
HL, I feel like I asked you what time it is and you told me how to make a watch JK JK

I will quit using the file I use on a horse's hooves and buy the NAPA part.
 
Hi eric,

Just a most wonderful idea !!!!!!!!!!!!!!! Love it.

I have quite a few my Dad's horse shoe files -- we always had horses years ago.

I just can't think how they could be used on a Model A other than roughing up the cylinder walls on new cylinder inserts so the new pistons & piston rings can seat far more rapidly ................... or maybe cleaning the bugs off of the front of one's brand new $850.00 Model A radiator .............. or even scraping the winter ice off of one's Model A fenders after a $5,000.00 new Model A paint job.

Maybe someone else can think of something useful.

Thanks, & Happy Father's Day.
 
Ign. points will last a long long time when dressed with a point file, and so will the files. Just remember to store the point file so as to avoid contact with any oil or grease.

Chet
 
FWIW,

A while back I tore down a pile of distributers. I noted that all the Ford script ones were in pretty good shape with nice shiny tungsten points. Most of the aftermarket ones were the same way.
The use Ford points showed minimal difference from my NOS Ford points. Out of all the points sets I have, most of them are perfectly fine and I would use them on my car. Yes, my car will get the NOS set points just because I can.

BUT

A couple of points sets had this white 'fuzz' coating on them. Interesting was the a set of el cheapo points brand new from many years ago. The point blocks were coated with the white fuzz too.
 
When I was a young man and all cars had points. Point cleaning or replacement was a very common service procedure. I was taught not to use a stone or sandpaper to clean points because particles of abrasive could become embedded in the softer point material, and that a fine file was the proper tool to use. If one point contact was pitted the other one had build up, I would replace the condenser, but if the point contact surfaces were the same I would not replace the condenser because that meant that the capacitive reactance of that condenser was a good match to the inductive reactance of the ignition coil. A new condenser might not be as good a match!
 
Couple of things...some sort of tarnish forms with time on points. I have found NORS points of very respectable old brands showing no electrical flow at all...recently, I found a distributor in the basement that I had rebuilt and checked out in about 1972 and put away unused. No contact at all until I cleaned them.
I recently bought the last two point files on the rack at our local Sears, and noted later that they had not been replaced. No wonder sears is headed down the hole!
There is a possibly even kinder and gentler tool to clean points, a burnisher strip that used to be available under the name Flex-Stone or Flexstone. That brand is apparently gone from the word but similar mildly abrasive strips are available to repair contact points in electronic relays. Someone on this forum a few years back had them available from his business, which involve pinball machine repair! These would I think be too mild to attack a really burnt or peaked-and-cratered set, but would be great for polishing off dirt and tarnish.
Another possible source of dirt and burning is oil mist blown past the distributor bushings and up into the cap area. This can be caused by lack of crankcase venting (like a damaged oil cap driven down over tube) or excessive blow-by from a tired engine.
 
H. L. Chauvin said:
Hi eric,

Per your reply #10, points are made with soft, non-ferrous metal & what you read is correct about not using just any "file" to clean ignition points.

If you ever clean your points with a regular high carbon steel "file", this particular "file" can cut through & remove this soft point metal with several swipes.

The 1930's were not void of uninformed mechanics; hence, with money so tight during Depression, this caution was written for not using said very sharp standard blacksmith's "files".

Now, if you ever buy an ignition "Point File" & try to remove all of the soft point metal from your points in a few weeks, please first go to Home Depot to buy a lantern with about 5 gallons of kerosene & an alarm clock; next, stop at a grocery store to buy about 3 weeks worth of groceries & bottled water; & on your way back, go to NAPA to buy a real ignition "Point File".

Then set up a schedule with your alarm clock & start filing away on your points with an ignition "Point File".

Then call us in a few weeks to let us know how much metal was removed from your points.

On the other hand with stones, there are different types of stones where most can sharpen Solingen steel knives; however, if you try to sharpen a good hard steel knife with an ignition "Point File", please buy at least 165 "Point Files" at NAPA & buy a full years supplies of groceries & kerosene.

Really not trying to be funny or rude in any sense or in any way, but in a humorous manner of instructions, I find that if one actually buys an ignition "Point File", & a regular "file" & tries both on a set of points, one will never forget that there is a remarkable difference between a blacksmith's "file" & that which is known as an ignition "Point File".

With sincere respect, just humbly hope this helps.
Click to expand...

I thought the good points were made from tungsten? Is tungsten not hard?
 
Years ago one of the first trouble shooting tips I learned about starting a non-starting Model A was to run a dollar bill between the closed point contacts. It will absorb any oil on the point surface as well as being abrasive enough to clean off the tarnish off.

But also years ago the dollar was a lot stronger!!! You may have to use a five dollar bill now to get the same results..:rolleyes:
 
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