Just a thought if you plan to stick with the Pertronix: Might want to have the distributor rebuilt if you've gone through everything else.

The Pertronix may be new, but it is sitting on a 45 year old piece of kit, with bearings that haven't gotten any tighter since it left the factory. It could be loose/"floating" at that particular RPM, especially without decent load. Benz Dr on here rebuilds them, BTW.

(You could get a new distributor, but if you go that route, you may as well get the one that comes with a built-in ignition and selectable advance curves.)

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