The Ford Barn

PGBuick · 08-17-2023, 08:26 AM

I am building a 36 with a 1948 59AB in it. The ignition is new, reconditioned 1948 front mount distributor with the dual points. I'm a bit new to this type of distributor, but research indicates this setup is quite good and will be perfectly fine for my intended use. I will add that the motor has a timing pointer and TDC mark added to it.

On later model (mid 60's) GM points setups I have used the single points to trigger a Streetfire MSD box. The beauty of this is the point contacts don't wear out, you get great spark, and there is a built in rev limiter. I have found it to be a great solution for my particular setup that no one makes an electronic ignition for.

My question is, could the dual point Ford setup be used in the same manner? Which set of points (or both) would be the trigger for the MSD? Where can I find an explanation of the theory/function of the dual points? Ron Holleran's book has an explanation of how the two sets of points closure overlaps, which allows for more duration of points closure, but does not explain completely how the points adjustment changes ignition timing. He does explain the vacuum break function in that it is a retarding device that removes timing under certain load conditions, which is very different from more modern distributors where the vacuum can adds timing for part throttle.
Thanks!
Pat

deuce_roadster · 08-17-2023, 08:55 AM

MSD is completely unneeded on a flathead. No mystery on dual points, they act as a single point but give more dwell.

1948F-1Pickup · 08-17-2023, 12:28 PM

With a dual point, the signal for an MSD (or other electronic box) is taken off the leading set of points. The other points are redundant, as dwell is determined by the electronics. You can remove the second set of points…..

PGBuick · 08-18-2023, 05:45 PM

Thanks for the info! Good answers. I'm not sure if I'll spend the extra money for the MSD box, but a rev limiter appeals to me.

tubman · 08-18-2023, 06:00 PM

Quote:

Originally Posted by PGBuick

Thanks for the info! Good answers. I'm not sure if I'll spend the extra money for the MSD box, but a rev limiter appeals to me.

I wouldn't worry about it. The ports and restrictive exhaust system pretty much take care of limiting the engine speed.

Drbrown · 08-19-2023, 09:17 AM

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Regarding interest in limiting rev's, and true or not, I remember old-timer's on these forums saying you can not "blow up" a flathead that has proper oil and whose valve train and bearings are in decent condition. I believe that statement pertained to the engine running under load but of course I never tested the concept.

08-17-2023, 08:26 AM	#1
PGBuick Member Join Date: Nov 2021 Location: Central Mass. Posts: 96	Ignition idea/question for 1948 dual point I am building a 36 with a 1948 59AB in it. The ignition is new, reconditioned 1948 front mount distributor with the dual points. I'm a bit new to this type of distributor, but research indicates this setup is quite good and will be perfectly fine for my intended use. I will add that the motor has a timing pointer and TDC mark added to it. On later model (mid 60's) GM points setups I have used the single points to trigger a Streetfire MSD box. The beauty of this is the point contacts don't wear out, you get great spark, and there is a built in rev limiter. I have found it to be a great solution for my particular setup that no one makes an electronic ignition for. My question is, could the dual point Ford setup be used in the same manner? Which set of points (or both) would be the trigger for the MSD? Where can I find an explanation of the theory/function of the dual points? Ron Holleran's book has an explanation of how the two sets of points closure overlaps, which allows for more duration of points closure, but does not explain completely how the points adjustment changes ignition timing. He does explain the vacuum break function in that it is a retarding device that removes timing under certain load conditions, which is very different from more modern distributors where the vacuum can adds timing for part throttle. Thanks! Pat

08-17-2023, 08:55 AM	#2
deuce_roadster Senior Member Join Date: Oct 2011 Location: Shelton, WA Posts: 3,800	Re: Ignition idea/question for 1948 dual point MSD is completely unneeded on a flathead. No mystery on dual points, they act as a single point but give more dwell.

08-17-2023, 12:28 PM	#3
1948F-1Pickup Senior Member Join Date: Oct 2015 Location: Socal Posts: 795	Re: Ignition idea/question for 1948 dual point With a dual point, the signal for an MSD (or other electronic box) is taken off the leading set of points. The other points are redundant, as dwell is determined by the electronics. You can remove the second set of points…..

08-18-2023, 05:45 PM	#4
PGBuick Member Join Date: Nov 2021 Location: Central Mass. Posts: 96	Re: Ignition idea/question for 1948 dual point Thanks for the info! Good answers. I'm not sure if I'll spend the extra money for the MSD box, but a rev limiter appeals to me.

08-19-2023, 09:17 AM	#6
Drbrown Senior Member Join Date: Oct 2013 Location: Glens Falls NY Posts: 1,267	Re: Ignition idea/question for 1948 dual point Sponsored Links (Register now to hide all advertisements) Regarding interest in limiting rev's, and true or not, I remember old-timer's on these forums saying you can not "blow up" a flathead that has proper oil and whose valve train and bearings are in decent condition. I believe that statement pertained to the engine running under load but of course I never tested the concept.