Pertronix ' Ignitor ' Benifits
Good question ! .
What it does is : drives the stock ignition system to it's maximum output all the time ~ this means better and hotter sparks , always ~ when slowly cranking it over on a 35° F January morning or after a 125° heat soak in Bakersfield , it'll roar right into life and idle smoother because the switching of the ignition coil's primary circuit is *instantanious* unlike with breaker points .
And , because the coil is producing maximum current , you can open those spark plug gaps to .037" ~ .040" to ensure proper ignition of the fuel charge .
So , it'll help light off that clapped out old 235 with 45 # in # 1 , 67 # in # 3 and 33 # in # 6 cylinders instead of cranking for a few minutes every time .
Lastly , because you're still using a stock coil , it won't chew up and wear out , dizzy caps , rotors and plugs , wires etc. .
There is NO down side to this system & because the engine starts faster the starter wears less and the battery retains more of it's charge so the generator works less and it's bushes and regulator contact points wear less .
Did I mention that it improves not only fuel mileage but off - idle performance gets a noticeable gain ?

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I hope this answers your questions and clears up any mis concepts .
No , my '49 doesn't have one (yet) as I keep having other bills to pay .