Im getting ready to fire the engine for the ellena and discovered i have the wrong coils. Im told and by other examples I have seen that the Tootsie Roll Style is the correct ones. I have also seen an example where they were not used but were vintage type with no resister on them. I have a build sheet for the car after mine and there is no indication on the build sheet what type of coils were designated. It does call out the single distributor on the build sheet - BUT no coil designation. Looking for some education, advise, what to look for - are all tootsie roll coils create equal?? Appreciate the thoughts...
when you use a coil without resistance then on the bottom there is no letter or only a K, if with resistance then there are the letters KW or only W ( bosch coils ). never heard about tootsie roll coils
the resistor is connected separately to the coil; not where the wires from the ignition switch and the distributor goes to? would be great to see a photo from the top if the coil, but this one looks original?
TJ, the tootsie roll is a classic American candy that in some ways looks like those cylindrical resistors. We just made that up and it term stuck. Not to hijack Ed's thread, but I would be interested in learning the advantages/disadvantages of having a resistor in the ignition, as it seems like some cars have resistors and some do not--and I am not referring to just Ferraris. Thanks. john
I do not have proof of the following, but in my opinion cars with the coils and distributors mounted at the front of the engine had internal ballast resistors. These were mounted on the inner inner fender in a fairly cool area. When Ferrari moved the distributors to the rear of the engine the air was hotter so they had to switch to an external ballast resistor to reduce the heat build up in the coil. Cheers Jim
John: Every 12 volt car has to have a resistor in the ignition system, otherwise the points will burn up. Many cars use a resistor wire from the ignition switch to the coil to drop the voltage, and some use an external resistor to achieve the same results.
This is interesting, as my old and new wiring harness, and ill double check this before i say 100%, does not have resistor wire running from the fuse box to the coils. So if that is the car, ill need to put some resistance in the wire......or use the tootsie roll coils..... This a true assumption? This is timely Dyke as I'm working thru my single dizzy and going to adapt your cap and rotor change. Now with the dizzy all apart, i can do this - hopefully easily.......
Ed: Ferrari always used separate resistors as opposed to resistance wire. Ford and GM (but not all their cars) used resistance wire and Chrysler used stand alone resistors. The Germans tended to place the resistance internally in the coils, and the British had no clue.
SO i see that greg jones makes vintage coils and he said his has a 3 ohm resistance , oil based..... so running these qualify for the necessary resistance needed? Is this the same thing as an external resistor? Sorry for all the questions, I'm a bit in the dark on this and trying to define the correct coil type for the car.
Dyke, thanks. I have generally not seen resistor blocks around the earlier types that predate the "tootsie roll". Are the resistors internal? But that would overheat the coil probably. john Image Unavailable, Please Login
John: I am trying to answer complex questions with too simple answers. Yes, the early Ferrari coils are internally resisted. Ed: Greg makes repro coils for the ones shown in Post #11 (and possibly other versions as well). i would try to find a set of the original tootsie-roil units. Since you are in Arizona, get in the car and personally go to GT Car Parts. I would bet, somewhere on the premises are the coils you are looking for.
Coils with approximately 3 to 4 ohms of resistance have an internal ballast resistor and do not need an external resistor. Coils with approximately 1 ohms of resistance need an external resistor. A resistor is needed in the system to prevent the points from burning up. The resistor drops the voltage to the points so they do not pit to as fast as they would with 12 volts. If you measure the voltage to the distributor you will find the voltage in the 6 to 9 volt range. Some systems supply the full system voltage while the engine is cranking to offset the voltage drop from starter motor current draw. Cheers Jim
ok thanks for the info....i saw bill yesterday and we discussed some of this as well as the GTC/4 dizzy cap and rotor. let me see what he has.....
The coil has an inductance. The resistor has a resistance. The are not the same thing. The primary and secondary coils, the spark plug, the capacitor, the resistor all from part of a damped electric oscillator. The purpose of the capacitor is easy to understand. When the points open, there is a rapid change in voltage because of Faraday's law. Capacitors act like short circuits to rapid voltage changes and thus keep the points from sparking. I am afraid that I never have thought before about the role of the resistor. But now I guess that it is there to keep the current low in the primary coil when the capacitor acts like a short circuit and the Faraday law is placing more than usual current into the primary coil circuit and to damp down the oscillations in the otherwise LC circuit that now becomes an LCR circuit. (Neglecting the coupling to the secondary coil.) ON THE OTHER HAND, what I just said off the top of my head may well be nonsense. Perhaps someone else has the correct reason and can explain it and save me the time and trouble of solving the equations of the electrical circuits.
The engine can also stop with the points open or closed. If closed, the current to the coil is only limited by whatever total series resistance there is. That's probably a consideration also.