Re: Volts to plug

Posted by John T on January 12, 2006 at 07:34:44 from (66.244.90.98):

In Reply to: Re: Volts to plug posted by hassanfortney on January 11, 2006 at 21:21:26:

Great Discussion Guys: Good point on those old Sun machines, seems they provided all the answers a person ever needed. As far as any minimum necessary dwell time, I dont see it as much of a problem on these old low RPM 4 cylinder engines versus a high RPM 8 cylinder where it may be a problem that there was insufficient time for the coil to draw current and saturate prior to the firing. After a certain finite amount of time in which the coil draws current (points closed) theres only so much energy that can physically be stored in its magnetic field (depends on the coils magnetic and inductive properties), and once that point is reached, it doesnt matter if you let it draw current for five minutes more, when the points open and the magnetic field collapses and the energy in the primary gets induced over into the secondary (mutual inductive coupling transformer action) theres still only so much potential energy which can be expended across the spark plug gap. A coil made with improved magnetic materials and better windings and insulation properties can do a better job of storing energy and transforming it with less heat losses and other energy wastes.

If youre trying to fire 8 cylinders from a single set of points with a single distributor cam and running at 8000 RPM, you then need to worry that the points were indeed closed for a sufficient time to store the max amount possible energy in the coil, but with 4 cylinders at 2500 RPM its not usually a problem. All this, of course, still assumes the air gap of the points (determines dwell time) is sufficient so proper switching action can occur absent any arcing over etc. I remember the old dual point Mallory Distributors which were developed to reduce point float and take care of the minimum dwell time problem discussed above. Of course, the use of an electronic current switch has made this old point technology a thign of the past except for us guys who love the old iron.

Take care yall n God Bless Funnnnnn Discussion

John T

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