8ba stumbles at freeway speeds

You are likely getting 'fuel pullover'. That occurs when the anitsiphon slug or ball is left out of the accelerator pump squirter. What happens at high speed is the depression is great enough to pull fuel out of the squirter, it'll come out in drops and dribbles and that is what creates the signature 'sputter', you pull the choke enough to kill the depression (that is the air signal in the carb, not the status of the drivers' mental state) and it can't pull fuel.
The antisiphin slug or ball is identified on any carb rebuild schematic so you can see if it there or not easily.
 
If the antisiphon ball is in there then my guess is you are running out of gas. I.E. you aren't filling the bowl fast enough to replace whats used. So it doesn't need bigger jets (probably compound the problem) but more fuel delivery. Raise the regulator pressure, check filter for debris. Also a fuel pressure gauge in the car can tell you lots..
 
Alright guys, the problem has been getting worse the last couple weeks to the point I haven't been driving it. I ditched the pertronix n went back to points, problem solved!!! I cruised at 80 on the freeway with no backfiring or wierd sounds at all. I can't say anything bad about pertronix because it's treated me well for3 1/2 years but I guess I'll just be keeping it simple from now on! Thanks for all the advice, Mike
 
glad to see you solved it i similar issue with magnetic breakerless dist . the generator and regulator is a "dirty" power source full of voltage spikes and fluctuations mordern electronics dont like that. Mallory igns sells a "power filter" to correct that issue its set up for their 3 wire ignitions
 
Glad you got it sorted. Always remember the rule that most fuel problems turn out to be ignition, and most ignition problems turn out to be fuel.
I know when I posted try swapping out the petronics and refit the points, May have sounded like I was barking up the wrong tree, I was using the above rule.
Martin.
 
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