Turbo Biscuit Posted December 23, 2012 Share Posted December 23, 2012 (edited) Revamping the ignition system on my '78 280z. Everything but wires and the coil have been replaced, the motor has been timed and is dead on. The problem I'm having is with the old coil there are misfires pretty frequently. Not so frequently that the car will stall at a light or that I can't idle at 800, but enough to where it bothers me. The misfire only appears with the timing light on the coil to distributor wire, it doesn't happen on any of the plug wires. I ordered a crane PS60 coil and installed it and the car ran like crap, the tach jumped when it started and then died (not permanently, just didn't work with the coil). I did an ohm check on it and the secondary coil was infinite, so I returned it and got a new one. I put the new one in today and the car started stronger than ever (although the tach still died), it sounded beautiful. Then it just stopped. The coil pack was warm, and the resistance on the secondary coil read 2k less than what it had before I installed it. Then I heard plugs firing inside the cylinder head for awhile after the car stopped. Now it won't start at all with the PS60 coil. Seems to me like I fried it. The 78 has no ballast resistor for the coil (it limits the current in the transistor module), only a resistor in the interior wiring for the tach. My stock coil runs at about 13Vac when the car starts, and as it starts to warm up, the voltage drops to 11Vac. Has anyone had any issues with this? Does the crane coil need a ballast resistor (2.2kOhm?)? Would I be better off buying a PS20 or 40 coil since it has the same specs as the stock coil? Thanks! Edited December 23, 2012 by Turbo Biscuit Quote Link to comment Share on other sites More sharing options...
morbias Posted December 23, 2012 Share Posted December 23, 2012 (edited) It says in the instructions a ballast resistor must be used... Edited December 23, 2012 by morbias Quote Link to comment Share on other sites More sharing options...
Turbo Biscuit Posted December 23, 2012 Author Share Posted December 23, 2012 Well MSA's website says to "retain and use stock ballast resistor". I figured since there was no stock ballast resistor I wouldn't need one. I'll grab a resistor and see if I can't salvage the coil. So if my stock coil runs without a resistor, what's the point of a nice 'performance' coil if I'm going to have to limit the voltage to it? Quote Link to comment Share on other sites More sharing options...
NorwegianZED Posted December 23, 2012 Share Posted December 23, 2012 For some reason you get both 9 and 12 volt coils. The 9v ones needs the resistor... I your coil says 12v you are in the clear if you send 12v to your 9v piece it will give the wrong output, overload then burn out. My boat caugth fire because of this last summer merry christmas. Quote Link to comment Share on other sites More sharing options...
Turbo Biscuit Posted December 23, 2012 Author Share Posted December 23, 2012 Ah, this makes sense. I wish I had known that there were two types before! Thanks and merry Christmas to you too Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 23, 2012 Share Posted December 23, 2012 It's the amps that produce the heat. It may be that the 78 igntion module flows too much current for the Crane coil. The PS60 shows a primary resistance of 0.4 ohms on their page (below). Compare that to the 78 Z spec. of 0.84 - 1.02 ohms and you can see that a lot more current is flowing through the whole system than the 78 module is designed for and maybe the Crane coil also. The coil may be designed to have more resistance in the circuit. You're probably lucky if you haven't fried the Z ignition module. The description says compatible with all OE electronic ignition systems but the 78 Nissan system might be a little too primitve. There's more to designing an ignition system than just matching primary circuit resistance but it is one important factor, just to keep the heat down. I'm an electronics rookie and probably always will be but I wouldn't even change the 78 coil specs. without "upgrading" the module also. The modules are over 30 years old and crapping out on a regular basis. Putting more work through it can't be good. http://www.cranecams.com/416.pdf Quote Link to comment Share on other sites More sharing options...
Turbo Biscuit Posted December 23, 2012 Author Share Posted December 23, 2012 I know I haven't fried the ignition module because it still works with the old coil. Perhaps it wasn't the coil that gave it up, but the transistor module that cut out from too much current. I think I saw a thermistor on the module board. It may have over-current protection on it. I will buy a resistor this week and test the coil again with the resistor on it. I was trying to figure out equivalent components to rebuild the ignition module in my last thread, just in case it did burn out in the future but was unable to identify the values on a few things. Quote Link to comment Share on other sites More sharing options...
NorwegianZED Posted December 23, 2012 Share Posted December 23, 2012 oh, i burned out my crane fireball xr700 unit last year bummer. it still "said" it was working with the status light on the unit. but the car was dead. new unit and it startet right up.... The right coil with the right output and you will be on your way Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 23, 2012 Share Posted December 23, 2012 Sounds like you already know a bunch. Did the resistance come back up when the coil cooled down? You said that it dropped by 2k ohms. The tach jumping aorund is a typical sign of the module going bad. But there could be other causes , my tach stopped working right (needle just quivered at ~500 RPM) after I installed a Z31 coil with a GM HEI module. A condenser/capacitor on the negative side brought it back to life. The tach and HEI module worked fine with a 78 Nissan coil, it was switching to the Z31 coil with the module that knocked it out. But the capacitor, a typical alternator style, fixed it. Some trivia... Quote Link to comment Share on other sites More sharing options...
Turbo Biscuit Posted December 24, 2012 Author Share Posted December 24, 2012 Indeed it was the module that must have cut out. Measured the amps on the OEM coil. 1.4A ac. With the PS60 coil, it's drawing 2 to 4 A ac ! I was mistaken about the resistance. It was good the whole time, I looked at the wrong spec. on the crane PDF and just got mixed up. I guess this means that the coil is fine with 9 or 12 since nothing in the Crane datasheet says anything about a resistor. I'm sure MSA just tells you that you must use the resistor in order to save your module. I have a capacitor I just haven't popped it on yet, I'll let you know if that fixes it after I get the new coil going. Thanks for the info! Quote Link to comment Share on other sites More sharing options...
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