Resistor wire - what's it for?

[[JP]]

What's it for? does anyone know? I've read about this ignition resistor wire, but not sure why its a resistor wire and if really required.

So, my 65 Chevy C10 has a 350 Buick engine in it.
The wiring was a mess as some of you know, I've redone the wiring.

The wire from the ignition to the coil was not a resistor wire, when i redone it I used 28/0.30, not resistor wire either.
All good, truck starts and runs like it used to before I ripped the wiring out.

Found there's a problem on the coil- if you tighten a nut too much then it wont work, so I bought a new coil.
this thing here:


now on the instructions it says I have to use a ballast resistor. which is fine as the coil came with that resistor:


but then I found this diagram online..



this diagram again mentions the resistor wire.... what is it for?
and another question... I dont have a wire going from the coil to the starter motor - why is this wire there? is it necessary?
All I have, in relation to starter motor (and was like this when I got the truck) is a wire from battery to starter motor, one from ignition straight to starter motor and that's it. truck starts and runs though.. so i'm also curious to know what is the wire to the coil for?
the original wiring diagram does show the wire going from ignition to starter and then coil, but on mine is going straight to the coil




So basically after all the babbling there is 2 questions:
what's the resistor wire for
and whats the wire from coil to starter motor for.

[ray_mcavoy]

Originally Posted by [JP]

So basically after all the babbling there is 2 questions:
what's the resistor wire for
and whats the wire from coil to starter motor for.

The resistor wire does the same thing as the ballast resistor that came with your coil. It reduces the voltage / limits the current to the coil to prevent it from overheating. And with a points ignition system that also prolongs the life of the points. Some electronic ignition systems (like the GM HEI) do not require a resistance wire or ballast resistor since their internal circuitry is designed to limit the coil current to a safe level.

The wire from the coil to the starter is a bypass wire. It temporarily bypasses that special resistor wire (or ballast resistor), feeding full battery voltage to the ignition for a hotter spark during starting.

Originally Posted by [JP]

but then I found this diagram online..

Hey! I recognize that diagram It's one I drew years ago for my points to HEI swap page --> http://rmcavoy.freeshell.org/HEI.html

[jtrichard]

X2 ray....JP some coils have the resistor built in and don't need the RES.wire or the resistor you have in your pic GM DID NOT use that type of coil OEM IF you use a OEM style coil and do NOT use some kind of resistor it will start great but you will burn points like crazy.... THE "HOT" start set up is the best (hooking a wire to the R terminal on the start solenoid as in the pic above

[[JP]]

ah!! excellent, thanks for the replies gents, it makes perfect sense now in my head.

The truck is new to me, I think I also need to open the distributor to check if there's still old points in there or one of those e-spark things

ahhhh yes it is!! I just noticed your username and it's what I saw on the page where I found that diagram!
i think most searches I do always takes me to your website

[_Ogre]

the resistor reduces points voltage to approx 6 volt to prevent the points from burning out
pre-55.2 trucks did not have the resistor as they were already 6 volt systems