Distributor cap/rotor button debris

[cjc56]

I have a situation that I have not run into before. When I restored my 56 tbird/ 312, I restored it back to stock with one exception: I replaced the points with Petronix electronics in the distributor and a Petronix coil. The engine runs great but when I take the distributor cap off there is small bits of black plastic that seem to be coming from the plastic edges of the rotor. There is nothing phyiscally hitting the rotor. It looks like something is arcing on the inside of the cap and ""blasting" off the edges of the rotor. Has anyone ever seen this before and if so how do you stop it?

 

[Jimz Bird]

Did you put a gasket between the dizzy and the block?
There should not be one as that little bit of extra height will cause the shaft to be pulled down by the cam gear and chew things up.

 

[frank long island]

the last petronics I put in fell apart all the magnets came off needless to say car ran like crap. more fine off shore engineering. lost my feel for modern went back to points

 

[miker98038]

The Pertronics and other HEI ignitions I've used have been fine, but I've had similar issues with lower quality cap and rotors. They don't seem to be able to take the higher voltage with disintegrating. Off shore, probably.

 

[dmsfrr]

Did you put a gasket between the dizzy and the block?
There should not be one as that little bit of extra height will cause the shaft to be pulled down by the cam gear and chew things up.

You are correct. It tears down the top bushing for the shaft and then gouges out the dist housing.
And getting the distributor rebuilt afterward is real expensive.

 

[cjc56]

No I did not put a gasket between the dist and block. And I have use these units many times on my restores and have had great success. I guess I need to try another/better cap and rotor.

 

[miker98038]

One other thing, but it's a long shot. If you think the cap/rotor failed due to spark.

I had one unit, don't remember when, where the electronic unit didn't "index" or "phase" properly. So when it fired # 1, or any plug, the rotor wasn't really pointing at the plug wire. Just on the edge. There was enough spark to jump and fire the plug, but it caused a lot of spatter. An old racer friend told me to, drill a hole in the bad cap between the coil terminal and #1 plug wire, hand crank the motor to #1,and make sure the rotor was lined up right. It's going to be a little off center, to allow for the advance, but it should be close. Like I said, a long shot, but you've got the bad cap.

 

[dmsfrr]

......
I had one unit, don't remember when, where the electronic unit didn't "index" or "phase" properly. So when it fired # 1, or any plug, the rotor wasn't really pointing at the plug wire. Just on the edge. There was enough spark to jump and fire the plug, but it caused a lot of spatter. An old racer friend told me to, drill a hole in the bad cap between the coil terminal and #1 plug wire, hand crank the motor to #1,and make sure the rotor was lined up right. It's going to be a little off center, to allow for the advance, but it should be close. Like I said, a long shot, but you've got the bad cap.

There was a previous thread here on Ford Barn about a misaligned rotor. Don't remember when.
The flat side (or notch) of the dist shaft that aligns the rotor should 'point to' one of the high spots on the cam for the points (pic 1), not one of the flat spots between (pic 2).

 

[miker98038]

Thanks, that's a better explaination, and a better memory.

 

[Ole Don]

The Pertonix I bought years ago had casting flash on the part that fit over the cam. Some time with a flat surface and some sand paper and all was good.