Points

[raygreenwood]

I just bought a set of the xp (blue streaks) NOS off ebay last week. The standard SMP points are probably 80% as good as the blue streak and are still available from NAPA, Rockauto...lots of places.....and are still easily twice as good of quality as what I have seen so far out of Bosch or anyone else.

The one difference I noticed long ago between the SMP standards and SMP blue streak....performance wise.....depends on where and how you drive.

The SMP points use a LOT of copper to produce a lower resistance shunt in the circuit. Less voltage loss and less/slower burning of points possibility. The SMP standards use a solid copper arm. The blue streaks have a solid copper arm that is wider and thicker and also a solid copper frame.

If you drive long high speed miles in very hot ambient conditions....like Texas and Oklahoma hot....over 100F in the summer.....over long miles you will notice that the copper arm slowly begins to bend Slightly.
In a bus....you would probably not see this as your engine compartment has pretty good airflow through it and you dont bank heat at the distributor. However on my car....a 412....which has virtually no airflow through the engine compartment. ....the distributor gets very hot. Over long miles....still longer than you see with poor quality points.....you see that arm bending slightly and it needs realignment at some point only in one axis.

The blue streak with a heavier arm has no problems with this.

Also most people have unconscious habit...mainly through low specific knowledge of plastics types....to instantly think a part is going to wear because its made of plastic...say as compared to phenolic circuit board type material that older points had their rubbing block made of.....and thats not true at all.

There are plastics...and there are "plastics".....
High end UHMW and nylon ALLOYS....and I make that note....alloys.....have much lower frictiln than phenolics and FR4/6 combinations.....and can have temperature ranges that while not as high as phenolics....are plenty high enough for ignition distributor use.

The biggest problem with longevity of nylon alloy rubbing blocks is not the plastic itself....but the DESIGN of the rubbing block and the condition of the distributor cam...AND....in many cases....the type of lubricant used.

In the case of high wear on nylon types of rubbing block Like those used on the SMP points ....it is usually a combination of rough surface on the distributor cam...coupled with grit and dust in the grease. The plastic alloy used on SMP products has no issues with virtually any greases I have found.

However the hard plastic non- nylon or UHMW based plastics found in the cheap "L" shaped plastic rubbing blocks found in econo points....the ones that like to snap.....will have a stress riser in the first place at the valley of the L...just from the molding process....and also appear to be made of crystalline type plastics that usually have issues with specific type of oils and solvents. ....that exploit surface cracks and stress risers causing them to crack.

One of the simplest and most visible examples of this issue is with acrylic plastic. If you cut a piece of it with a saw....either sheet or block....and take a simple rag soaked with anythjng rrom paint thinner to alcohol to xylene....virtually organic solvent....and just get it close enough to get vapors on the plastic.....the plastic will instantly start cracking and crazing from thr edges inward. The only way to prevent this is to flame treat the cut edge to simultaneously seal stress cracks and relieve surface stress. Oils and greases can do the same thing....and to many types of crystalline plastics.

So if I were going to use cheap points with cheap unknown plastic type rubbing blocks I would use a dedicated silicone distributor grease. Ray

[cdennisg]

I stopped at NAPA yesterday with the correct GB4173 part # (I had the numbers transposed the first time) and both the P and X suffix cross to their CS313 point set.

Interestingly, I also gave them a Beck Arnley part # 1716984 (good looking set on Rock Auto) and it crossed to their CS312. The only difference int he CS 313 and CS 312 is the direction the wire leaves the terminal.

It appears, at least in my area, that the Standard points are NLA at NAPA, and whatever part # given will get you one of two sets of their Echlin points. They had a plastic rubbing block (may not be an issue, as seen above) but were otherwise very nicely made. Cost was @ $7.00/set. I plan to buy some just for comparison's sake. I'll use them eventually.
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nothing

[Wildthings]

My belief is that phenol holds the lube better than nylon and other plastic typically do. Unlubed phenol doesn't seem to wear well, but when lubed barely wears at all, maybe wearing a thousandth of an inch in 20K miles. I started seeing problems with some point sets maybe 35 years ago and have searched for points with phenol wear blocks ever since. I suspect that companies that make points using various plastic wear blocks, don't actually do much of any testing on their product, especially since most of the cars and trucks that use them probably get very few miles on them anymore.

For those of us the still but lots of mileage on our old rigs, points have become one more problem to solve.

[raygreenwood]

[airschooled]

My fuel economy took a hit last week, and I noticed a slight schizo-jump in my tach from 2,000 to 2,400. I didn't think much of it, other than how useless a tach is in an early bay with a 1600 single port… Then I realized I've never set dwell on this distributor. Actually, I didn't even use a feeler gauge. I just slapped it in from a swap meet with some Bosch grease.

I like to think that whoever made these points years ago stopped making them shortly after. The usual "pit/tit" that I see on high-milage points didn't exist. Instead, there was a round wear pattern, almost like a valve adjuster screw wear pattern on a valve stem.

The markings on the inside:

UNIPOINT
Taiwan

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[Wildthings]

[raygreenwood]

The domed wear pattern of a pair of point, contacts. ...is actually better to have than the pointy "tit" pattern. With the pointy one. ...as Wildthings noted....there is usually more than a points issue going on.

The frosted wear look in a domed shape on points...very even and not on the edges... ut all in the center is usually due fo points surfaces not being ground flat (concave usually).....or.....if its right in the center and fried on both fixed and moving points....it sounds like overheating is a possibility as well. Either from the metals themselvea not handling the heat generated....or excessive heat being generated somewhere in the train of ignition....again as wildthings suggested. Ray

[airschooled]

...Did the pictures not load where we can see that these points literally blew the rotating pin cap off and bent the top arm??

I'm not worried about the wear pattern. I picked the distributor out of a junk pile as a spare and it went thousands of miles on two cars before grenading the points. I don't even know what the contact surfaces looked like before today.

I only mentioned the wear pattern being circular, because the top horizontal plate of the moving arm was detached, allowing the contacts to move all over the dang place.

Robbie
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[old DKP driver]

As was mentioned from Wildthings and Ray the "PPO" plastic rubbing block
which was used on LATER Bosch points along with the phenolic lasted much longer than what is now used and also had a domed pattern on the contacts.

I believe that the spring tension is really the cause on the newer Bosch point sets but, I have never used any of them.

PPO PLASTIC is harder than the older phenolic (BROWN COLOR) and the same phenolic compound (brown}was used from 1967 onward for D-Jet trigger points and they did not wear out the same as ignition points.

I have probably 20 sets of old stock bosch points and will continue to use them as I have NEVER had a failure with wear.

my $ 0.02
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V.W.owner since 1967

[raygreenwood]

[airschooled]

[Tom Powell]

These are new points with about 2000 miles. Probably the pitting is due to a weak/bad condenser. The engine would start, die, and no restart.

The final solution:


Aloha
tp

[airschooled]

Tom, I think I had your old points in my bus.

Robbie
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[timvw7476]

I don't get it.....
Tom's second & final image is pointless.

[SGKent]

see points fly into pieces?
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[Tom Powell]

[timvw7476]

i was just punnking

[SGKent]

[airschooled]

[CrRusty]

Hey Tom P - isn't the coil perhaps at fault, when the points pit so quickly? What coil are you using?