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1st Gen Ram Tech'93 & older Rams: This section is for TECHNICAL discussions only, that involve 1993 Rams and older. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
do you still have the factory coil off the 91? i think the TBI trucks may have had a coil with an internal resister which is how they look like the old ones but are able to be run with full 12v. they are usually marked if they have an internal resistor or not. i don't know why you can't run a regular full voltage coil with the stock ignition.
I have the coil that came with it, I don't think it's the original. I'll have to look at it and see if it has an internal ballast. I know it's oil filled you can hear it. Are all the mpfi coils full voltage, or does the ECU/ecm have a low voltage wire that feeds them?? I haven't seen any ballast resistors since they all went to fuel injection, computer controlled.
The oil filled coils use the oil to cool the coil. The epoxy ones don't have a way to get rid of the heat so i believe they use a thicker wire to form the coil. Therefor can handle direct 12V. If that's all you are worried about get a MSD6A ignition box. It doesn't need a ballast resistor and performs better than conventional ignitions because it fires the coil 6 times compared to 1 of conventional ignitions. I have one on my power wagon and love it. Faster starts and better fuel economy. Some people say they don't like them because they quit working but i never had an issue with it.
i doubt you would really notice any difference between a well maintained stock 4 pin ignition system and msd especially on a stock engine. my 81 starts just as good as a fuel injected vehicle if not better hot or cold with stock ignition system and no ballast bypass while starting.
My apologies to the PO for thread jacking. I'm not really worried about the ballast resistor ignition. But I just wanted to see what other options are out there without going hei. So if I can find a pigtail for the Magnum coil, I can run it without the ballast resistor, and I could team it up with the mds unit. Not that there is anything wrong with the cylinder oil filled coils, I think the square coils come with higher voltage option.
i doubt you would really notice any difference between a well maintained stock 4 pin ignition system and msd especially on a stock engine.
Well mines not stock, cam headers modded spread bore Holley and Edelbrock intake. I hooked up the MSD box with an old school Accel super coil. Got more voltage than any stock coil. If you are going to run the MSD you don't need the ballast resistor. I actually bench tested the combo and if you back the coil wire off from the ground it will actually spark over to the negative on the coil.
Im not running a stock 360 mag. Either. Only thing reused was the block, crank, and rods. But, it does start fast, after sitting over night, I let the fuel pump run a couple seconds, and it's running as soon as I turn the key to start, I don't think it even makes a full revolution on the crank.
Just getting around to gathering all the bits for this conversion. In the hot rod magazine article they suggest using a crane PS-91 coil https://www.hotrod.com/articles/conv...ion-to-gm-hei/
But on checking with summit racing seem they no longer have this coil. They suggest I use a Fast PS-40 coil https://www.summitracing.com/oh/part...0040/overview/
but the pic shows it used in conjunction with a ballast resistor. I was hoping to simplify my wiring but deleting the ballast resistor so not sure what coil I should use
if you are doing a full hei conversion with hei cap you could run a newer dodge magnum or ford e type coil. the main issue with most 12v coils is they seem like they are meant to be used with a HEI style cap unless you can make your own spark plug wires.
