Dual point distributor question

[pbiggs]

Does anybody know if the condenser used in a dual point distributor (65 Formula S) requires a specific mfd. (microfarads) condenser? My parts book shows 1818757 to be correct condenser for all dual point distributors and 2098058 for most all single points.
Is the dual pont condenser smaller in physical size to fit the more crowded plate but has the same microfarad value?
Thanks for your response

 

[dukeboy440]

talk to @halifaxhops he rebuilds, tests and plays with these things with his fancy old equipment

 

[halifaxhops]

Does anybody know if the condenser used in a dual point distributor (65 Formula S) requires a specific mfd. (microfarads) condenser? My parts book shows 1818757 to be correct condenser for all dual point distributors and 2098058 for most all single points.
Is the dual pont condenser smaller in physical size to fit the more crowded plate but has the same microfarad value?
Thanks for your response

Same value the difference is one has a copper strap, the other a wire, The MFD should be on the flat side. I have both in Mopar nos if wanted pm me.

 

[67Dart273]

I believe the reality is the cap should match the coil. In "olden times" you could actually buy somewhat smaller or larger capacity values to correct points pitting. Been so long I've forgotten........points pitting on one side meant use larger, other side meant use smaller

................and just like that................Al Gore's dubya dubya dubya strikes again

 

[pbiggs]

Same value the difference is one has a copper strap, the other a wire, The MFD should be on the flat side. I have both in Mopar nos if wanted pm me.

PM sent

 

[pbiggs]

I believe the reality is the cap should match the coil. In "olden times" you could actually buy somewhat smaller or larger capacity values to correct points pitting. Been so long I've forgotten........points pitting on one side meant use larger, other side meant use smaller

................and just like that................Al Gore's dubya dubya dubya strikes again

View attachment 1715062195

Very interesting information, thanks for your response.

 

[KitCarlson]

I am late following this but, the theory about the capacitor on dual point in voles the following.

When the first point closes the primary igniton is energized and starts to build current. There would be no need for a capacitor across the points. The current would start at zero, hence not a point spark issue. The need for having the capacitor, is for when the second point opens, the current wants to continue, results in high voltage and sparks flows at final opening point. The capacitor opposes the high voltage spike an routes the current away from point. The problem is the capacitor is also across the first point, and is discharged when points close again, so the first point sparks due to having the capacitor.

So as Del said, the value changes what happens on each point. The capacitor helps one, a disadvantage to other.

Modern transistor driven coils do not have capacitors, except for a few hundred pF of capacitance in the collector to emitter junction. They also do not need dual points, because coil charge is controlled in an optimal method.