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Author Topic: Single points or dual points????  (Read 1945 times)

Offline Jeff Kay CLC#7630

  • Posts: 90
  • 1941 Cadillac Series 63
Single points or dual points????
« on: November 04, 2007, 01:03:49 AM »
Which is better to install in a 346 cid flathead; single points or dual points?  What are the advantages to dual points?  Are there any disadvantages?  Who sells dual points braker plates?

Thanks,

Jeff Kay

Offline CLC#12231

  • Posts: 62
Re: Single points or dual points????
« Reply #1 on: November 04, 2007, 01:40:41 AM »
Advantage:  Higher dwell for better coil saturation and hotter spark.

Disadvantage:  Higher cost.
Frank

Offline TJ Hopland

  • Posts: 10193
Re: Single points or dual points????
« Reply #2 on: November 04, 2007, 04:33:39 AM »
Here is a site I found that explains it fairly well.  They appear to be dealing with a 4cyl but later talk about V8's.

http://www.mgaguru.com/mgtech/ignition/ig200.htm
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline 35-709

  • Posts: 5364
  • The most valuable antique is an old friend.
  • CLC Number: 4719
  • Name: G. Newcombe
Re: Single points or dual points????
« Reply #3 on: November 04, 2007, 11:04:21 AM »
I can see no real advantage to dual points with a stock engine.  If you are building one up for high performance I would go electronic.  If you don't care about originality the Pertronix is one good way to go.   
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

Doug Hpuston

  • Guest
Re: Single points or dual points????
« Reply #4 on: November 04, 2007, 10:22:52 PM »
Back in the fifties, Dynaflyte dual point breker plates were popular for about any engine's distributor. They had a very good ball bearing suspension, and were  highly sensitive to the action of the vacuum advance. As already explained, they made ignition more efficient.

I have installed a Dynaflyte plate on one of my '41 Cadillacs, and it worked well for a while. But, the cam follower blocks on the two point sets wear at different rates, even as similar as you can get them. That involves re-removing the distributor and re-adjustment at closer intervals than you'd check single points.  This is done on a distributor machine. As good an idea as the dual points were, they became sort of a nuisance, and I removed the second set of points, left the Dynaflyte plate on it, and went away contented.

While the dwell angle will drift normally with single points, it becomes more critical with the dual points, and always wants to be out of adjustment. You'll probably never feel the difference with or without dual points.

Offline Jeff Kay CLC#7630

  • Posts: 90
  • 1941 Cadillac Series 63
Re: Single points or dual points????
« Reply #5 on: November 06, 2007, 01:21:20 PM »
Thanks for all the advice.

I like the idea of using the dual points braker plate with just one set of points, just becase it has many more ball bearings.  My thinking is that the more ball bearings, the more steady.  The original plate has only three ball bearings.

 

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