Surge problem at speed

Have you check the reluctor gap in the distributor? Also, to just replace he distributor is pretty generic. What is you static and total timing? Is the vacuum advance hooked up and have you disconnected it to see if you issue goes away? Have you tried a different ignition box and is the case to yours grounded really well?

The Pertronix has a janky way to adjust the mechanical advance. If you want an easy to adjust drop in the Jegs billet distributor is pretty good considering the price and it uses the stock cap. A member here, halifaxhops sells curved stock distributors as well if you don't to mess with setting one up yourself.

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