Buggies Gone Wild Golf Cart Forum - View Single Post

73eldo · 01-21-2022, 11:10 PM

If you are using a ballast resistor it should be between the + wire to the coil and the + terminal of the coil. Unless you are using some unusual coil you should not need one.

The main reason for systems usually multi cylinder engines like cars having a ballast resistor was for current limiting. That need comes in during normal operation but was especially important if the key was on and engine wasn't running. Without it the coil would explode in a minute or two if the engine happened to stop with the points closed.

The HEI module does the current limiting electronically for normal operation and its doesn't matter where the engine stops, even if the points are closed you only get one pulse. With the carts we kill the power as soon as we take our foot off the pedal so if the engine isn't turning there is no power anyway so even if something failed stuck on in the module there would not be power on for extended times without the engine turning.

If you were doing diagram #1 or #2 4.7K ohm is correct for R1. If you are doing #3 its 3 resistors so more like 3k. If you put a 4.7 ohm resistor there its going to run hot and cause a lot of arching at the points, like in the range of how much arching and wear there was before the conversion so you won't be gaining much reliability.

R1 has nothing to do with coil resistance or that side of things. The transistor is basically an electronic relay that in this case is used to reverse the signal. When the points are open the transistor gets 12+ signal via the 4.7k resistor. When the points close that 12+ signal is getting shorted to ground so the transistor no longer sees that voltage and triggers the module.

If you didn't have any resistor there its a dead short to ground and something is going to fail. Basically the resistor becomes the 'load' on that part of the circuit when the points are closed. Since the transistor doesn't need much power the resistor can be really high. No reason to waste power or cause heavy load on the points.

I did have one engine I did this conversion on where I constantly had to clean the points and on that one I dropped the resistance to like 1k ohms and that seemed to do the trick. That caused just enough arching to burn off any moisture or dust on the contacts but note that if you lower the resistance you need to increase the wattage of the resistor. I think in my case I did 5 watt, maybe overkill but its what I had laying around.

01-21-2022, 11:10 PM	#32
73eldo Gone Wild Join Date: Jul 2014 Location: St. Paul Minneapolis MN USA Posts: 522	Re: HEI Conversion SUCCESS If you are using a ballast resistor it should be between the + wire to the coil and the + terminal of the coil. Unless you are using some unusual coil you should not need one. The main reason for systems usually multi cylinder engines like cars having a ballast resistor was for current limiting. That need comes in during normal operation but was especially important if the key was on and engine wasn't running. Without it the coil would explode in a minute or two if the engine happened to stop with the points closed. The HEI module does the current limiting electronically for normal operation and its doesn't matter where the engine stops, even if the points are closed you only get one pulse. With the carts we kill the power as soon as we take our foot off the pedal so if the engine isn't turning there is no power anyway so even if something failed stuck on in the module there would not be power on for extended times without the engine turning. If you were doing diagram #1 or #2 4.7K ohm is correct for R1. If you are doing #3 its 3 resistors so more like 3k. If you put a 4.7 ohm resistor there its going to run hot and cause a lot of arching at the points, like in the range of how much arching and wear there was before the conversion so you won't be gaining much reliability. R1 has nothing to do with coil resistance or that side of things. The transistor is basically an electronic relay that in this case is used to reverse the signal. When the points are open the transistor gets 12+ signal via the 4.7k resistor. When the points close that 12+ signal is getting shorted to ground so the transistor no longer sees that voltage and triggers the module. If you didn't have any resistor there its a dead short to ground and something is going to fail. Basically the resistor becomes the 'load' on that part of the circuit when the points are closed. Since the transistor doesn't need much power the resistor can be really high. No reason to waste power or cause heavy load on the points. I did have one engine I did this conversion on where I constantly had to clean the points and on that one I dropped the resistance to like 1k ohms and that seemed to do the trick. That caused just enough arching to burn off any moisture or dust on the contacts but note that if you lower the resistance you need to increase the wattage of the resistor. I think in my case I did 5 watt, maybe overkill but its what I had laying around.