Stumble/miss at 2100 RPM Options

[Rrrockhound]

I've got a pretty persistent stumble or miss around 2100 RPM. She purrs like a cat above and below that, but at that RPM, I get stumbling if I rev in neutral (no load) or a miss if accelerating from a stop. I tried disconnecting the throttle switch to see if it would go away, and it actually got a little worse. I cleaned the throttle switch tracks anyway, but no dice. What say you? Trigger points, maybe? It's a 2.0 D-jet, with new plugs/wires/cap/vacuum lines and Pertronix unit.

[jk76.914]

I've had similar problems over the years....

First, I found the the PO had removed the resistor that is in series with the cylinder head temp sensor. Put one in and it solved it. I seem to think it was only on acceleration, though- under load. Don't recall trying it no-load. Mine is a '76, and I couldn't find any reference to the resistor in any of my manuals, so I didn't know it was supposed to be there until someone asked me about it.... This was about 20 years ago..

Second time was last month. This time, my Pertronix module was interfering with the distributor cap! It's a 20 year old unit, and never gave any problems, until I replaced the cap as regular maintenance. My previous cap was aftermarket- black- and must have had better clearance. The other symptom was that the idle wouldn't settle down to 900, instead hovering around 1400. First thought that my vacuum retard was toast, but it seems the dist cap was skewing the module, and the breaker plate below it over towards the cam. The top of the module was machining grooves in the shaft of the rotor, and the twist on the breaker plate was causing it to stick in the advance position, increasing the idle..... Fix was grinding down the module- just enought but not too much- and even then, I had to relieve a spot inside my distributor cap with a drum sander in my Dremel..... I'll have to do that from now on I guess when I change the cap.

I think I have a Rev zero Pertronix- It's really old, and pictures of the new ones look like they're physically smaller.

Just my thoughts.....