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I just finished recurving my Ford vacuum advance distributor. It has a Pertronix unit installed. Today I test drove the vehicle most of the day at I noticed a pronounced hesitation and or miss when the vehicle is travelling at lower RPM (1700-2800). This is most noticeable at lower speeds. I do not notice it on the highway at 2500RPM and 65 mph. All I did was change to a lighter spring. It may not be the problem, but it did not miss as bad before I changed the springs. I do have a moderate cam (216 dur, .484 lift). The car idles great and feels great a higher RPM with no missing at all. Timing is 12* initial 32* final.

Other info -carb Autolite 4100 (480 cfm), engine 306 cid, T5 tranny.

TIA

Steve
 

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did it miss before you made the changes?

ok..re-read...so it missed a litte..then you changed the springs..and now it misses really bad?

Do you ahve the correct clearance for your pertronix? I think it's supposed to be .030". Did you remember to hook your vacuum line up to the carb? Are you sure teh new springs had some tension on them when the plates are closed..(zero advance) If not..slightely bend the tangs to apply more tension to the spring.
 

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Assuming that there is no change after changing the spring back to the original, advance the inital timing 2 degrees at a time, it will likely tke care of the hesitation. If not check the power valve.
 

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You have increased your timing advance too much. Either reset your initial advance or put in a stiffer spring. I'm basing this on a hesitation of a "jerking" while at a constant speed.
 
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