Coil and Wiring
Thread Starter
Advanced
Joined: May 2008
Posts: 58
Likes: 0
From: Apex NC
Coil and Wiring
I have read many posts regarding the coil and its wiring, but can't find an answer to my question.
I have a 70 BB and noticed the two wires to the + terminal on the coil are hotter (to the touch) than I think they should be. The coil (not original) has printed on it "External Resistor Required". Both wires to the + terminal have an outer wrapping, one going to the starter solenoid and one going to the junction box at the fire wall with the other wires in the harness. To my knowledge, there is not an external resistor (like the earlier model years) on my 70.
My contact at an auto parts store says he has a coil that has an internal resistor that I should be using. What coil is the right one?
Is the wire running to the firewall (on to the ignition) acutally provide resistance?
Car runs fine, just concerned about the heat being generated by the wires.
Any help will be appreciated.
I have a 70 BB and noticed the two wires to the + terminal on the coil are hotter (to the touch) than I think they should be. The coil (not original) has printed on it "External Resistor Required". Both wires to the + terminal have an outer wrapping, one going to the starter solenoid and one going to the junction box at the fire wall with the other wires in the harness. To my knowledge, there is not an external resistor (like the earlier model years) on my 70.
My contact at an auto parts store says he has a coil that has an internal resistor that I should be using. What coil is the right one?
Is the wire running to the firewall (on to the ignition) acutally provide resistance?
Car runs fine, just concerned about the heat being generated by the wires.
Any help will be appreciated.
Melting Slicks
Joined: Mar 2007
Posts: 2,520
Likes: 11
From: Hinckley OH
It's been a long time since I did anything with a points and coil ignition, but, I think the coil gets pretty warm. I don't think you have a problem. The wire to your firewall should be a resistor wire so I think you're OK on resistance as well.
Melting Slicks
Joined: Apr 2007
Posts: 3,189
Likes: 111
From: Tolland CT
If you know the manufacturer and part# of the coil you have now, maybe check to see what that manufacturer recommends.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
While you can measure lower voltage from that 'resistor' line, it isn't there to lower the voltage. It is there to limit the current flow in that line so that it doesn't over-current the coil. The only way to know if that line is a 'resistance wire' line is to disconnect it from the coil connection, then use a pin-probe to poke thru the insulator at the fuse-block end and measure the wire resistance with an ohmeter. That wire should measure 1.35 ohms (or so) if it is resistance wire. If it is just normal wire, you will get a very low resistance reading (under .2 ohms). If you have regular wire, you will need to replace it with resistance wire or install a 1.35 ohm ballast resistor in the circuit to replace that load. Then you will need to have a coil made for your system (use with external resistor) so that it will all work correctly. You may also just have a bad coil or a defective condenser.
