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Single to Dual Point Dizzy Conversion

1805 Views 10 Replies 6 Participants Last post by  DPeterson3
I'd like to convert from a single to dual point distributor on my Alfetta. It's a '76 SPICA car, the distributor coming out is the original one with new points, cap, & rotor (not sure of part number), and the distributor going in is a dual point Marelli S166B. I don't think it's a normal later model SPICA dizzy. There's a Flamethrower 1.5ohm oil filled coil on it with the factory ballast resistor hooked up, but I plan on putting the original coil back in and then eventually an OEM spec or Bosch Blue coil. Does anybody know how I would go about doing the conversion without adding all the relays and such associated with the later model SPICA? All I want is the slight performance boost from the dual point, I don't care about the emissions or fuel economy. (And yes, I'm aware that more points=more pain, my old man has already informed me of that.)
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My understanding of the Alfa dual point set up was that provided a spark timing change at high RPM to improve emissions and fuel mileage.
Right! The two sets of points aren't positioned 180 degrees apart; they don't open at the same time. So if you wire the two sets in parallel, you will get too much dwell for a given point gap. If you narrow the gap to achieve the correct dwell, only one set would be open at the beginning and end of the coil discharge.

Back in the 50's Mallory and other companies made dual point distributors that were considered speed equipment. But 70 years later that technology has been superseded by electronic ignition such as Pertronix or MSD. If a Pertronix is beyond Alfa Tasteless' budget, a well-tuned single point system is probably the best approach.
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