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Mallory Series 25 Dual Point Distributor Questions

General engine tech -- Drag Racing to Circle Track

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Cris
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Mallory Series 25 Dual Point Distributor Questions

Post by Cris »

I am helping a friend get his 1963 Corvette get sorted out. Like a lot of these survivors, previous owners have put their own spin performance improvements. His car looks to have a Mallory series 25 dual point distributor with the tach drive. It has no provisions for vacuum advance.

I am not sure I quite understand the purpose of the the dual points. This distributor has eight lobes on the cam so each set of points is opening and closing every time a cylinder needs to fire. From what I have read, there may be a reliability (redundacy) improvement with two instead of one set of points operating. There may also be an advantage in that one set of points opens slightly earlier than the other and the other closing a little later. This way they share their duties, thus extending the life of the points.

Also, any comments on the quality of these distributors? We are planning on leaving it there once we get a new cap, rotor, and points in.

Thanks, Cris
ClassAct
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Re: Mallory Series 25 Dual Point Distributor Questions

Post by ClassAct »

Cris wrote: Mon Jul 27, 2020 2:39 pm I am helping a friend get his 1963 Corvette get sorted out. Like a lot of these survivors, previous owners have put their own spin performance improvements. His car looks to have a Mallory series 25 dual point distributor with the tach drive. It has no provisions for vacuum advance.

I am not sure I quite understand the purpose of the the dual points. This distributor has eight lobes on the cam so each set of points is opening and closing every time a cylinder needs to fire. From what I have read, there may be a reliability (redundacy) improvement with two instead of one set of points operating. There may also be an advantage in that one set of points opens slightly earlier than the other and the other closing a little later. This way they share their duties, thus extending the life of the points.

Also, any comments on the quality of these distributors? We are planning on leaving it there once we get a new cap, rotor, and points in.

Thanks, Cris

Dual points increase dwell time. Those are great distributors.
Cris
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Re: Mallory Series 25 Dual Point Distributor Questions

Post by Cris »

ClassAct:

The dwell improvement is achieved by staggering the point openings?

Thanks, Cris
ClassAct
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Re: Mallory Series 25 Dual Point Distributor Questions

Post by ClassAct »

Cris wrote: Tue Jul 28, 2020 1:44 pm ClassAct:

The dwell improvement is achieved by staggering the point openings?

Thanks, Cris
Yes
bigmike
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Re: Mallory Series 25 Dual Point Distributor Questions

Post by bigmike »

The quality of those old mallory distributors was very good I think I still have a couple around. Finding good quality points these days not so easy.
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