What is the coil voltage on a Mopar. I have heard it is 7VDC because of the ballast resister as opposed to GM HEI 12VDC or is that only at start-up?
Thanks FABO
Thanks FABO
The normally brown bypass circuit, IGN2, supplies full battery voltage to the coil for start. The "run" line through the ballast actually goes dead during start. During start you should see whatever the battery is, during cranking, and you want at least 10-10.5V or moreWhat is the coil voltage on a Mopar. I have heard it is 7VDC because of the ballast resister as opposed to GM HEI 12VDC or is that only at start-up?
Thanks FABO
or maybe he's just asking about the concept.
HEI includes a current limiter.
The other systems of the time, and GM's previous (points) system control the current by reducing the voltage. The more curent through the resistance, the more voltage drops. Chrysler's resistance is mounted such that at driving high speeds it cools more and slightly reduces resistance. That's concept anyway.
Chrysler goes over that here
Ignition System Analysis (Session 259) from the Master Technician's Service Conference
I am running a Mallory All-In-One marine disty the correct ballast and a MSD coil. It works fine and has a lot of advance curve options. After reading the article I was curious if there is a hotter spark with an HEI.
The reason I am asking is that I saw an article on how how much better the HEI system is and that it delivers full voltage to the coil at run. No ballast. This article was showing Mopar and Ford guys how to convert to HEI using their stock distributors as the signal. Claiming to provide better performance. I have a friend who actually did this and hid it all inside an orange box. Wondering if theres any performance gain for the trouble.
Spark It Up: How to Convert a Ford or Mopar Distributor to GM HEI
Maybe.
We can break up the question into two parts:
The voltage it takes to jump the spark plug's gap depends on the conditions in the chamber, and in particular the conditions at the tip of the spark plug.
density of the mixture, the portion of the fuel that has vaporized -> which depends on the how well its been mixed into the air, along with termperature and pressure in the chamber, and the fuel's distilation curve. I'm sure there's more but you get the idea.
Bottom line is some conditions will require a higher voltage to jump the gap and start the kernal of flame.
Then there is the length of time the current keeps flowing; and how much current flows during that time.
If a fuel and conditions are such that a higher current actually helps the kernal grow, then can sometimes do that better than other systems.
There's guys who can explain this better than me, but thats why its not a cut and dry answer.
Here's what the voltage looks like at the spark plugs.
Notice the voltage to jump the gap is higher than the voltage needed to keep the spark burning.
Then when the electric sparking is finished, there's usually still electical energy left in the system. That's the oscillations.
There's a more technically accurate explanation for the oscillations that others can explain better but to me it represents left over energy.
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