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Dave_W 10-28-2009 05:45:11 204.14.57.6 738732 Report to Moderator	I have posted a few messages over the past week or so about having trouble getting my 9N to start. I had it running, but it was becoming harder and harder to start, and finally to the point where it wouldn"t start at all. I cleaned the plugs (more then once), gave her the MMO treatment, rebuilt the carb (needed it anyway), readjusted the new points and adjusted the timing, all with no luck. Well last night, I finally figured out what was wrong - One of the 2 new resistors that I had installed for the 6-volt coil (I converted tractor to 12 volt) was cracked, and as soon as I touched it, it fell apart in my hands. I bypassed it, turned her over, and she fired right up. She quickly created a smog in the barn as the MMO started to burn off, but I think I solved my problem. I am ordering a new 12-volt coil and will just stick with the 1 resistor. My guess is that the resistor was still allowing current to flow, but the resistance had to have been quite high and the coil probably wasn"t getting enough juice to provide good, consistent spark on all 4 cylinders. Probably was slowing getting worse too, which is why I went from hard start to no start. [Reply]   [Send Email]
Dell (WA) 10-28-2009 08:59:44 172.191.224.18 738769 Report to Moderator	Re: 9N Hard Starting Resolved in reply to Dave_W, 10-28-2009 05:45:11   Dave.......remember, us guessers are only as good as the guessee can describe the problem. Thanks for the follow-up. The modern 12-volt squarecan frontmount ignition coil still needs this mandatory "infamous ballast resistor". ......Dell, yer self-appointed sparkie-meister   [Reply]   [Send Email]
Dave_W 10-28-2009 09:30:43 204.14.57.6 738772 Report to Moderator	Re: 9N Hard Starting Resolved in reply to Dell (WA), 10-28-2009 08:59:44   Mine was shot, and I was told by parts supplier that I could just use 2 of these - should I replace the broken one with an original resistor setup? What ohm is the original supposed to be?   [Reply]   [Send Email]
Bruce (VA) 10-28-2009 10:34:17 24.125.26.10 738781 Report to Moderator	Re: 9N Hard Starting Resolved in reply to Dave_W, 10-28-2009 09:30:43   "Mine was shot, and I was told by parts supplier that I could just use 2 of these -" Which is why he is a parts supplier & not a mechanic. Ask him to explain the difference between a ballast resistor & a fixed resistor. As I said, and as Dell said.....use the OEM resistor at a minimum. Make a decision regarding a "12v" coil or keeping your 6v coil & adding a resistor. Either way, it's going to be a crap shoot if you do not measure the coil resistance. 50 Tips   [Reply]   [Send Email]
Dell (WA) 10-28-2009 09:55:20 172.191.224.18 738775 Report to Moderator	Re: 9N Hard Starting Resolved in reply to Dave_W, 10-28-2009 09:30:43   Dave......the "infamous ballast resistor" changes resistance with its temperature; from about 0.4-ohms when very cold to about 1.7-ohms when very hot. Normal running resistance is about 1.2-ohms. The ballast resistor was Ford's scheme to work with cold 6-volt batterys in the days before DieHards (which die eazy) The 6-volt squarecan ignition coil is really a 3-volt coil PLUS the infamous ballast resistor turns it into a 6-volt coil. Its the LAW, Kirchhoff's Law. The ceramic resistor you show is actually rated at 0.5-ohms. You would need 2 of them in series like flashlite batterys (0.5 + 0.5 = 1.0, isn't that amazing?) to kinda replace the "infamous ballast resistor" that yer squarecan ignition coil needs. BYTE the bullet, use the real ballast resistor. Your coil will live longer and start eazier. .......Dell, yer sell-appointed sparkie-meister   [Reply]   [Send Email]
Bruce (VA) 10-28-2009 05:55:59 24.125.26.10 738735 Report to Moderator	Re: 9N Hard Starting Resolved in reply to Dave_W, 10-28-2009 05:45:11   Congrats on getting it running, but until you find out the resistance of the coil, you will be playing a very expensive guessing game regarding the value of the resistors you will need in the circuit to keep from melting the coil. Technology & materials being what they were in the 30's, that square coil would melt if it ran on much more than 4 amps for any length of time. (see tip # 38 for an example). In order to get a hot spark at the same time the starter was drawing max current from the battery, a ballast resistor was added in the ignition circuit. What that did was add about .3 ohms of resistance in the circuit, added to the 1.5 ohms of the coil. That got you 3.5 amps or so at start up. As the voltage increased when the engine was running to about 7.5 volts, the resistor heated up, adding more resistance in the circuit. 1.0 ohms hot, plus 1.5 ohms of the coil got you down to 3 amps or so to keep from melting the coil. The same rule (actually, Ohm's Law) applies to a 12v circuit. I= E/R. Current equals voltage divided by resistance. It used to be before the "Land of Almost Right" started making coils that you could count on a 12v frontmount coil as having 3 ohms of internal resistance & the 6v coils as having 1.5 ohms or less. Thus, thanks to Ohm's Law, you could calculate what additional resistance you needed in the circuit to limit coil current to 3.5 amps. So, you will need to measure the internal resistance of that alleged 12v coil & see what it is. A digital multi-meter has two probes & a switch. Set the switch on resistance. Put one probe on the top of the coil & the other on the pigtail at the bottom. It will give you a reading in ohms. Lets just say it reads 3.0 ohms. Your OEM ballast resistor (which you must use) is about 1 ohm hot. A coil a 3.0 ohms, plus the ballast resistor at 1.0 ohm (hot) gives you 4.0 ohms resistance in the circuit. Your 12 volt alternator puts out 14.5 volts. You need to determine current (amps). 14.5 v divided by 4.0 ohms gets you 3.6 amps; that will work just fine. But, and this is the problem......what if the coil is only 2 ohms? Do the math. 14.5 volts divided by 3.0 ohms gets you 4.8 amps! Not good! And, if the coil is less than 2 ohms (and some are) it will fry quickly. So, to get it to 3.5 amps, you need another resistor in the circuit. Either that, or keep spare $30 coil around. You are actually better off, coil longevity-wise, to keep the 6v coil, the OEM ballast resistor & add whatever additional resistance you need (as you did) because those resistors act as heat sinks to keep the coil cooler. 50 Tips   [Reply]   [Send Email]