SBC points type Dist, my coil has "12 Volts R" do I need to run a Ballast Resister? It starts really good without a resister and after running a few minutes the coil is not getting even warm but I dont want to burn up the points What do ya think ? TIA MIKE
Even though your car is running good, it really does need the ballast resistor. It drops the voltage to the points to about 9 volts and helps keep the contacts from burning. 12 volts (and higher) tends to make the contacts erode alot quicker. Though, the 12 volts is applied during the "start" mode. But, only until the motor is running. Hope this helps!
Thanks for the reply I guess Ill be a bit more specific I thought most coils were 6 or 9 volts rather than 12 so if the coil is 12 is the resistor still needed ?I have heard about the points life cycle being shorter but I thought it also had to do with the primary voltage on the coil? Im wiring the car now making up my own harness if a resistor is used how do you bypass it during start up using a push button starter switch? Thanks Mike
Try this: http://www.chevyhiperformance.com/techarticles/45618/ and this: http://groups.google.com/group/alt....67b8e5f9ea1/aae1b074ac348809#aae1b074ac348809 My understanding is, with points, regardless of the coil, you need a ballast resistor. My 396 SS Chevelle ran great with 12 volts to the points with a 12 volt (stock) coil...but it burnt the points up fast as hell. Doesn't matter if the coil is for 12 volts (that's what you want). It's the wiring that matters.
All 12V point igntion systems require a resistor. GM and Chrysler used a ballast style resistor usually on the firwall. Ford used a resistor wire. I have seen some people install a resistor on a Ford not knowing the wire was resisted. You can use a coil with an internal resistor. The coil you say you have has an "R" on it which may indicate it is internally resisted. The coils I sell say "external resistor required" if it is not internally resisted or "no external resistor required" if it is internally resisted. At start up, the start circuit bypasses the resistor. When the key is turned back to the run circuit after startup, the point circuit goes through the resistor.
I don't know how the factory did it, the oil pressure switch would be a method. The version I heard is when the engine cranks you still should have 9 volts to start up with, so the ignition needs to work at that minimum voltage. Another version is without the resistor the circuit forms a hartley/colpitts oscillator, and the engine will run on without the resistor depenting on the other loads. I did this myself when I rigged a cooling fan off the distributor in a pinch. The engine ran on for 5 min with the key off.
Pete, Sounds like when you hooked up your fan to the distributor you back fed the ignition circuit, bypassing the key switch. Accessories should not be hooked up to the distributor for power. This also can happen when putting an internal regulated alternator on a vehicle that originally had an external regulated alternator. The use of a one way diode solves this problem by letting the current only go one way, kind of like an electrical check valve. The factory had the wire that goes to the distributor during the start circuit run off the back side of the resistor. This would bypass the resistor and send full voltage to the distributor. When the key is placed in the run circuit, the current going to the distributor then was sent through the resistor dropping the voltage.
Pete, The factory did it in 55-58 (chev)with a ceramic bodied resistor between switch and coil +.We have all wondered about the usually unused small post on the Delco starter solenoid-when the solenoid is energized this post becomes energized so a wire was run to the coil side of the resistor providing the coil with 12v when cranking but putting the resistor back in the feed when the cranking was stopped.Starting in 59 a resistance wire was used instead of the resistor block and the bypass for cranking was still effective.Coils are available that need no external resistor but I have no knowledge of them being used on American cars there were common on the Kohler K-series and Magnum engines like on Cub Cadet.I have known people to use the resistor between coil and Dist. it seems to make no difference.
Mike, is the "push button starter switch" setup from an early ford? And is the starter button the kind that grounds to the dash and only has ONE wire coming from it? Or does the "starter button" have two leads coming from it? Next, if the coil your using is an "after market" (and you ARE using a 12 volt electrical system) you need to follow the recomendations of the coil manufacturer. As dmarv says, coils can be either INTERNALLY resisted or EXTERNALLY resisted. If yours is "Internal Resistance"; then NO further resistor is needed. BUT; if it does need a resistor, and you are using an EXTERNAL STARTER switch - "push button starter switch" - (NOT off the ignition key) then a small relay; powered when the button switch is on - start position - and hooked to a full 12 volt source - could be used to "bypass" the coil resistor.
Just came to me, use your ohm meter, low voltage side of coil should be very near dead short. Internal ballast coil should be up in the Meg ohms. I think..
Thanks for all the replys I was going to use the ford starter button but due to my hurry to get thing thing roadworthy I just put a universal keyswitch in instead using a ballast and a secondary wire from "r" terminal on solinoid to coil it works fine now and I dont have to hassle with it Thanks again for all the help Mike
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