Thanks all for your help in advance. 1966 F-250 4x2 that I've had torn apart for the last year or so. Finally put everything back together (nothing major - heads off and a bunch of cleaning, timing set, water pump, etc.) and it runs pretty good but is making this horrendous chattering noise. Used a socket extension up to my ear and I've decided it is coming from the distributor (as best I can tell). I removed the points and installed a Pertronix electronic ignition. I pulled the distributor apart and can't find anything that's causing the noise. Timed to about 12 degrees. Video is attached.

Things I looked at:
- pulled valve covers and the new edelbrocks aren't hitting the rockers in any way. Noise continues with valve covers off.
- replaced new distributor cap with old one and noise continued.
- took vacuum advance out of the equation and still noise.
- I'm lost.

https://photos.app.goo.gl/MS1PtoUYHPfHDEBA7

Truck runs ok. A little low on power, but that's how it was before. Any help is super appreciated. Thanks!

 

Is the rotor hitting the cap?

 

You say you pulled the distributor apart. Does that mean you removed the vacuum can and the advance plate and looked at the centrifugal advance weights to see if they are in their proper place? If not you need to do that. Because those are about the only think in a distributor that can make a lot of noise. If the rotor hit the contacts in the cap one of two things happen it machines itself some room and stops making noise or there is a big explosion and you have a bunch of broken plastic. If it were mine and I was certain it is the distributor I would pull it and inspect it on a bench where I could keep track of all the little parts.

 

Lot's of questions...

How's your oil pressure? Might be a problem below the distributer in the oil pump.

When you tore it down and reassembled did you reuse the pushrods - and they went back in the same place?

Hows the chatter when you rev it. I would assume it increases with the revs but if not that would be telling of just some sort of vibration.

Also would be curious for you to remove 1 plug wire at a time to rule out other issues.

And yes really inspect the distributor for wear as mentioned above.