points failure question

[yackee]

Hi all,

I have been tracking down an intermittently firing right cylinder on my T3. I re-gapped the points (I am still a relative virgin when it comes to adjusting points), swapped out the coils and plug wires and it got much worse, until I lost the right cylinder entirely.

I pulled the right-hand side point so I could look at it for problems (this was the first time I pull the points all the way off). Before pulling them, I re-checked the gap and it seemed a bit "wide" but not too much. I compared the old point to a set of new ones i had on the shelf, and after a bit of staring I noticed that on the old point, the fixed half of the point  (the one you move when doing your adjustments) had a hole all the way through the center of it. I assume this means that it is worn out! But I guess I am wondering, what happened to make the hole? Did I have the points set too tight? The face of the movable half of the points doesn't look like it went through any great trauma.

Any advice helping me diagnose the underlying cause would be much appreciated.

Jason

[pehayes]

Depends on the manufacturer.  Some points are a solid 'disc'.  Some points are a 'donut'.   Point surfaces burn when the condenser begins to fail.  Does it look like this 'hole' was machined through cleanly or like it was burned through by a torch?

Patrick Hayes
Fremont CA

[yackee]

Actually it look like the hole is machined I guess. The points with the hole are Magnetti Marelli. The hole is smooth and right through the center and there are no burn marks.

The points without the hole are not branded, but I got them from MG Cycle.

[Kiwi_Roy]

Try swapping the condensers over to see if the problem changes sides.

Pull the plug caps and measure resistance from cap to chassis, it should be same on both sides 5 - 8 KOhms I'm guessing

[acogoff]

     If you have the original bosch metal caps remove them and sell to some sucker- er collector. New wires and NGK caps may be all you need. And if a hole were burned in one side of the points there would be a mating mountain on the other one, so good chance they are made that way.

[charlie b]

I bought a new pair of points for a car many years ago and had the same thing.  Seemed weird at the time, but, they worked well.

I figured at the time that someone decided since points 'wear' in the middle to just leave that part out :)

[redrider]

The hole was thought to be a heat sink.

[wymple]

The hole is for heat relief, whether that works or not. One of the biggest overlooked problem with points is being square. When the points close, the 2 surfaces should contact each other perfectly square, or they don't function properly, burning at the edges and not lasting long. I dress the contact surfaces with fine emery dragged thru under some pressure to make sure the points are virgin clean, followed by a dollar bill to remove any residue. If they are not square, you simply bend the arm a bit till they are. I can't count the number of times I've gotten into points that had no lube on the cam.

[ruote]

Yes, the cam/rubbing block needs to be lubed.  Distributor cam grease is stiff, non-fiber grease.  I suppose it is still available.

 The pivot point also needs a tiny bit of oil; if the pivot does not work freely the points will not follow the cam.  This may be heat related.  The spring also must be sufficient to follow the cam and not bind. 

Suggest dressing the points with sandpaper rather than a file.  When the points are dressed with a file, the points are open by the thickness of the file and will not match when they close.