In an old style (points type) distributer, does the rotor actually rub on contacts inside the cap? When my car is idleing I can feel and hear a rubbing sound inside my distributer.
I've never noticed this in any other car that I've had. I just put new rotor and cap on last week but I never really paid atention to this before so I dont know if it did it with the old parts or not. The parts that I put on were cheap Auto Zone parts.
Ron

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70 Chevelle SS396
66 Nova SS 327
95 Z28 Convertible.
Aces 3081, TC #54 Gold

Ron, The rotor does not actually rub on anything. But if you look closely you will see an octagonal block that rotates with the distributer shaft. Like a cam it contacts the rubing block on the points and opens and closes them. Make sure you use a little light lubricant on the rubing block to minimize wear.

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hometown.aol.com/mkrauser/gmracing/gmracing.htm (http://hometown.aol.com/mkrauser/gmracing/gmracing.htm)


70 Chevelle Fathom Blue
70 Malibu Convertible Midnight Regatta Blue

Chicago - Suburbs

No, it does not rub the contacts. Pop the cap and see if it looks like there is rubbing. I would check to make sure the cap is seated properly on the distributor, and make sure the rotor is tightly mounted to it's mount. Also make sure that the center contact arm is still in it's correct location and not bent or twisted. I have had cheap caps where it was hard to tell if it was seated properly.

Contact rotor to cap should be easy to see. Just look at the terminals in the cap and the rotor firing blade end.

What usually causes this is the dist being on the ragged end of the end play spec. GM says dist end play should be between .009 to .090. If it is near the .090 end, the rotor can hit the terminals.

The other responses should be eliminated first, then if this problem still exists, pull the dist out and see if the end play is too much. Shims are available from dist shops, other GM dists from the wrecking yard (point and HEI use same shims), and speed shops (from Mr. Gasket and other suppliers).

Shoot for no more than .019 or .020, to no less than .010 to .012.

When a Chevrolet dist runs, the dist mainshaft is pushed (thrust) upwards by the gear angle it is cut with. The shaft will move upwards and so will the rotor. Possible contact will follow.

If the dist is a point dist and has had a drop-in electronic ignition installed that uses a bolt under the rotor trigger, then the rotor will, in effect, be moved upwards twords the cap, by the trigger piece. You always must shim a dist that has one of these trigger pieces to avoid cap terminal to rotor firing tip interferences.

Hope this, and the other suggestions, help.

[This message has been edited by IgnitionMan (edited 03-09-2000).]