Dual points for increased dwell??

34fordy said:
Now this is interesting. How could the Ford engineers have missed such a simple principle like that?
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Again, I'm just applying deep thought rather than something I've heard or read.

1932.

Plastics was in it's infancy. No nylon. The rubbing blocks were cloth/resin/thermoplastic. (Tufnol?).

It might be that they were not able to do the long lever type setup because of the wear characteristics of the materials available at the time. If you had one thou wear you would have 2 at the points.

Someone must have thought of that setup at some time, I wonder who was the first to adopt it.

Edit: It would appear Cadillac used points like the type we have been discussing in 1932. (Maybe earlier).


Mart.
 
As previously said above, there are two types.

Remember, closed points charge the coil and open points cause the coil to throw the high voltage to the spark plugs.

One way to explain it is the distributor turns 360 degrees and there are 8 times the points have to open, that leaves 45 degrees for each time the points have to open and close to fire each cylinder. In that 45 degrees, the points have to swing open and swing closed, leaving a lot less time for them to remain closed (dwell). The mechanical limitations of this action make it hard to get more than 30 degrees of dwell.

One way is to have dual points that "hand-off" the dwell time so that the opening is theoretically at the 45 degree mark per cylinder with no time lost from the opening and closing action. When the first set opens, the second is still closed for a couple degrees.

The other way is to build two four cylinder distributors in one, then each point set has 90 degrees of space to play in.
 
How long do you figure we can dwell on this thread? Maybe if there were more points...

Sry I can't resist a punny joke. 51 MERC-CT started it :D:D
 
Anybody remember the Sanchez Cagle Stude ?...2 flatheads. Belmont Sanchez owned a Stude dealership in Cal and built the car with Blackie's motors in '53....it was a brand new Stude........nobody ?
Charlie ny
 
Charlie ny said:
Anybody remember the Sanchez Cagle Stude ?...2 flatheads. Belmont Sanchez owned a Stude dealership in Cal and built the car with Blackie's motors in '53....it was a brand new Stude........nobody ?
Charlie ny
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Sounds cool.... only thing I could find was the Sanchez cagle 200mph grocery getter. '53 Studebaker with a 454 Chrysler hemi.

Any pics by chance?
 
Alaska Jim said:
One reason for dual points is to reduce point "bounce" at high speed/rpm
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How does that happen? It would seem that point bounce is directly controlled by the strength of the points spring. The chances of point bounce are doubled with two sets of points.
 
At least for a part of the time that the coil has current flowing through it, both points are closed. During that time both would have to "bounce" open in order to break the circuit. During the time both sets are closed, I guess you could say the chance of point bounce is cut in half, not doubled.
First, one point closes which allows current to flow. Then the other one closes which does nothing. Then the first point opens, which does nothing because the second set is closed. Then the second set opens which stops the current and as the magnetic field collapses in the coil, a large voltage spike is created for a short time.
 
Jim in Wisconsin said:
At least for a part of the time that the coil has current flowing through it, both points are closed. During that time both would have to "bounce" open in order to break the circuit. During the time both sets are closed, I guess you could say the chance of point bounce is cut in half, not doubled.
First, one point closes which allows current to flow. Then the other one closes which does nothing. Then the first point opens, which does nothing because the second set is closed. Then the second set opens which stops the current and as the magnetic field collapses in the coil, a large voltage spike is created for a short time.
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That makes since that I did not think of in terms of the point bounce. Although there is only 10 degrees of overlap so it only helps for 28.5 percent of the cycle.
 
But if the dwell is somewhere around 30 degrees, then the overlap is most of the time.
I think that's right anyway.
I'm too old to think hard anyway.
It's snowing real bad here in Wisconsin, I'd rather be in Tenn.
 
Some of the hot rodders back in the day were also using dual coil set ups which required either dual caps or one cap on top of the other so that the high tension could be delivered. These used two sets of points and two condensers as well as the dual coils.
 
rotorwrench said:
Some of the hot rodders back in the day were also using dual coil set ups which required either dual caps or one cap on top of the other so that the high tension could be delivered. These used two sets of points and two condensers as well as the dual coils.
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In addition, Mallory made a special coil with two primary windings and one secondary. This allowed them to effectively market a "Dual Coil" distributor that used a standard "flat-top" cap. They had two sets of points and two condensers, each alternately feeding one primary winding. This allowed them to get by with one high tension lead from the coil to the cap.

There have been a couple threads on the H.A.M.B. about these. It seems that over the last 50 or 60 years, the coils and distributors have become separated and people can't figure out how they work.:confused:

I once had a 1948 Seagrave fire engine that had the Pierce-Arrow derived V12 engine. The engine had dual ignition and had 24 spark plugs (H10's BTW), two distributors and 4 coils. It was impressive looking, that's for sure.
 
tubman said:
In addition, Mallory made a special coil with two primary windings and one secondary. This allowed them to effectively market a "Dual Coil" distributor that used a standard "flat-top" cap. They had two sets of points and two condensers, each alternately feeding one primary winding. This allowed them to get by with one high tension lead from the coil to the cap.

There have been a couple threads on the H.A.M.B. about these. It seems that over the last 50 or 60 years, the coils and distributors have become separated and people can't figure out how they work.:confused:

I once had a 1948 Seagrave fire engine that had the Pierce-Arrow derived V12 engine. The engine had dual ignition and had 24 spark plugs (H10's BTW), two distributors and 4 coils. It was impressive looking, that's for sure.
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That Seagrave sounds pretty cool tubman. I've seen some of the dual ignition flathead heads over on the hamb with 16 spark plugs, they are something else.
 
The actual Lycoming BB V12 engines are pretty rare since Auburn only made 14 speedsters with that engine. They only had single spark plug ignition for those. When American LaFrance purchased the rights to the engine and tooling, it was changed to dual spark plug ignition so this is how a person can tell one from the other aside from the engine data plate and various casting markings.

The Seagrave engines were made from a Pierce Arrow design V12. Those old fire trucks were big and heavy so they needed a powerful engine and a lot of gearing to get them going in a hurry.

Lincoln V12 distributors were modified to work for flat V8s as well.
 
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