I've been reading up on this and I think I'm getting conflicting stories, so I apologize for asking a question that may have already been answered. My question is about the yellow wire that went to the R-terminal. 1959 Chevy 1978 350 Pertronix ignition in a 1970 distributor body I'm replacing the stock 1978 starter with a 1998 mini starter. 1. I have a wire with an inline diode. It is supposed to connect to the yellow wire that went to the R-terminal. Does the other end connect to the large terminal that connects the solenoid to the starter body (fat yellow wire in the pic)? 2. Do I need yellow wire/diode at all with a Pertronix ignition, or do I just eliminate the yellow wire completely? Thanks!
You just need the single wire to energize the solenoid. Voltage to the ignition from the starter won’t be needed if your using a Pertronix at full voltage. I can’t remember on a 59 if the ballast resister was eliminated but if it was a resister wire from the ignition switch was used. Once started check the voltage coming to the coil. If it’s lower than battery voltage your car still has the wire.
Mine is running points,but the wire that has the in line diode does go to the large lug that has the cable coming out of the barrel.
X2 on what Jimmy six said. And the yellow would be were the diode goes if you we’re still using points. but make sure it is put in the rite direction.
Thanks! Well, it's been running for years WITH the yellow wire and the Pertronix. Doesn't that mean I need it? That's what I don't really get. Is there a harm if I use the diode and don't need it?
Diode is just a one-way electric current valve. Allows current to flow one way, but not the other. I don't think you need the diode in your situation, but it doesn't hurt either. Diode is used to prevent backfeeding, but your yellow lug does not have any voltage or current except when engaging the starter. Nothing to backfeed.
1959 (car) had a resistance wire in the loom for the ignition coil. Pertronix system wants a straight 12v (in the directions it tells you eliminate the resistance wire or ballast). The "R" terminal gives a straight 12v to the coil on a point system only upon cranking, I've eliminated the wire when putting in a permanent magnet newer starter on cars with points and they still started fine. The only reason I can think of that yours has a diode is so the coil/ignition doesn't back feed into the starter when it's running (IF that wire is going from the "R" terminal to the 12v (+) side of the coil now). If the yellow is running to the 12v (+) side of the coil only then you don't need it.
Early ignition switches did not send power to the coil in the start position, only in the run position. The power came from the starter, once running it came from the ignition switch. That's why there is a wire from the starter. Bill
I was taught that with points ignition that during cranking the battery voltage drops to 10-11 volts. Supplying the points even lower voltage given the fact that it was already low due to the ballast resister or resistance wire. So only around 4 volts. The R terminal supplies tru battery’s voltage during cranking to aid in the engine to start then when the key is returned to the start position the points are only running the 7 volts. The mini starter has no R terminal because it was designed for electronic ignition and didn’t require it so there pulling battery voltage from the yellow wire which is a hi amp load. Personally I don’t like the idea as I mentioned if the Diode is not put in the correct way when you turn the key to the run position it will energize the brushes and Cause the starter to spin and with only a piece of 16 or 14 gauge wire things will get hot. It won’t pull the bendex in and crank the engine. It will just spin the motor. So if it’s not needed I would not install it. But that’s just me.
I agree, don't use it if not needed. But, with many ignition switches, there may not be any voltage to the coil in the start position, coming from the ignition switch, only resisted voltage via a ballast resister or resisted wire in the run position. There has to be a switched battery voltage source to the coil while starting. The starter circuit ends up being the switch and yes, there has to be a diode installed in that wire. Put a test light on the coil and turn the key to start position, if there is power, then that wire from the starter is not needed, provided the wire going to the ignition is not resisted aka HEI. We do not know what type of ignition switch the OP is running. Bill
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