Worn-out Distributer Cap Carbon Brush

GPierce

GPierce

Well-known member
500 miles on new A-12115 Distributer Cap. ??
I was checking the newly installed original points from NAPA as my timing had changed slightly at 500 miles and found this. I expected the point gap to close up slightly but not a worn out rotor brush. Noticed the brass particles when I glanced at the cap and thought gee I need to investigate where those brass particles came from.
 

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I also installed new rotor. Good point, the rotor was fully seated I thought as there just a little springy feel as I set the cap on. Not being fully seated would certainly cause that problem.
 
I would think Brass particles are from the rotor or body terminals. You need to “ with no side play” on your rotor shaft, set the gap to around .025” on all four body ****. Also check to make sure all four lobes of the distributor cam give you the same point gap. As for the carbon button wearing out prematurely, you may not have had the rotor fully seated as you surmised. The other possibility is the spring pressure from the top of the rotor is too much. When you set the cap down, you should have a small amount of spring pressure.
 
The brass dust was from the the worn down brass bushing surrounding the carbon brush. The brass bushing wear can be seen in photo. The rotor and plug contacts **** are untouched. I did have very slight spring back from the cap when I put it on. The hold down springs snapped right on. The distributer body had just been overhauled by a vendor and shaft and bushings were new. I am still leaning toward soft carb or the rotor was not down tight on shaft.
 
Chuck Sea/Tac said:
I would think Brass particles are from the rotor or body terminals. You need to “ with no side play” on your rotor shaft, set the gap to around .025” on all four body ****. Also check to make sure all four lobes of the distributor cam give you the same point gap. As for the carbon button wearing out prematurely, you may not have had the rotor fully seated as you surmised. The other possibility is the spring pressure from the top of the rotor is too much. When you set the cap down, you should have a small amount of spring pressure.
Click to expand...

There you go again Chuck with that technical talk "body ****".;)
 
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