Dan, In a recent post on a thread somewhere here you stated that a non-functioning vacuum advance would result in a single cylinder miss. Would you care to elaborate on that a bit please? Why does this happen?

Thanks, Sam

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IIRC it had everything to do with the vacuum advance being hooked up to the #6 intake manifold runner, in that particular case. Less to do with the ignition system, and more to do with a vacuum leak that only one cylinder sees.

That was back in a post by "60 Plymouth": Low idle vacuum, sluggish throttle response, low power in Engine. He had a bad vacuum advance dashpot that was sucking air, and connected to a vacuum sorce in number 6 intake runner. The introduction of additional air into just one runner caused number six to run lean at idle due to low volume of air-fuel mixture flow.

Once engine was running faster than an idle the small amount of additional air added to number six became insignificant at higher rpm.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

A lot of that was speculation before I'd got back to say what my setup was - my vacuum advance is hooked up to the port on the carb.

On an engine with everything else intact a leak in the #6 runner causes #6 cylinder to have a leaner A/F ratio. If your vacuum advance is hooked to ported vacuum then this cannot happen. I believe a leaky vacuum can would cause all cylinders to run lean (extra air being introduced at the carb instead of just one runner.

I believe the same problems can be found if you have leaky vacuum accessories hooked to the #6 runner though (power brakes, defoggers, central locking if you got the 'fancy pants' options on my car).

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1960 Plymouth Belvedere 4 door sedan
Stock 60 225
Push button 3 speed Torqueflite
Right Hooker

Thanks. That is clear.

Sam

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