Ballast resistor and petronic ignitor 3

[john chalk]

hi all -- ignitor 3 is in and r unning OK. but theres a glitch.

ballast voltage to relay - switches 14 volts back to coil (flamethrower 2) then to ignitor 3 - all OK and running. switch off ignition switch and engine keeps running!  there is 4 volts of residual voltage in the circuit. what I would like to do is bypass the ballast resistor and see  if that fixes as I currently run the coil off the ballasted voltage (12.8volts) but would prefer to feed the flamethrower coil the full 14 volts.  

from memory the ballast is in the wiring harness in the engine but please advise location and thoughts on increasing voltage to the coil

cheers

[john chalk]

ok no probs - no mine is not drawing 20 amps I just applied ohms law but theres more to it than that I suspect.. will get it sorted now and just tap off as you have.

[Jason Edge]

If you are pulling 20 amps you definitely have other issues. Have you tested your amps draw?  As I recall mine with the Pertronix Ignitor III ignition and Flamethrower III coil (0.32 ohm primary resistance) pulls about 1.5 amps at idle and 2.5 to maybe 3 amps at hi rpm. I was concerned about exceeding amperage draw until I considered the fact that the resister wire taps into the same "pink" ignition feed from the fuse box as the kick-down switch pink wire I am tapping into! 

The instructions are pretty simple .. just trace the resister wire from + side of coil terminal back to the source behind the resistor wire (e.g. fuse box) of the fire. In our case it is the pink ignition wires and with the THM equipped cars you have it right there in the engine bay ready to tap into. Per the instructions, just run a 12 gauge heavy insulator wire from "switched 12 volt ignition source to the coil and igniter you will be fine.

Here is a good illustration of the primary cranking harness showing the path of the resistor wire back to the pink ignition wire circuit and also shows the pink kick-down wire and connector for the THM kick-down switch. Just use a tap in and run a 12 gauge insulated wire to coil and disconnect the resistor wire and you are all done. If you are concerned about shorting you can add a 10 amp inline fuse. (a 5 amp would probably be more than enough).

 

Here is that picture:

 

 

 

[john chalk]

jason sorry another question. the flamethrower 2 is 0.6 ohms so its drawing 20 amps? whats your advice to protect the circuit if I use the kickdown switch wire?

[john chalk]

thanks Jason I will look into that.  Just further to my last any reason why the ignition circuit is not fused, based on the factory wiring diagram?

[Jason Edge]

With 64's with THM transmission you can get a full 12 volt " switched" supply by tapping into kickdown switch wire. For others you can tap in to pink wire behind the resistor wire to coil behind firewall. Remove primary cranking harness firewall grommet bracket 3/8" hex metal screws and pull wiring forward and you should be able to just barely access the junction with pink wires and tap in from rhe engine compartment. Again, with THM kickdown wire you have the wire right there to tap into. There are pictures and illustrations in the Wiring pictures album accessed from our help page under wiring.

[john chalk]

thanks David.  I note the ignition circuit has no fuse that I can see. I will tap behind the ballast resistors (i see 2 in the circuit diagram) and fuse the connection. 

[David Thomas]

I'm running the Ignitor II with matching flame thrower. I ran a switched full voltage line from the fuse box to the coil and ignitor. I disconnected the ballast wire from the coil and taped up the end. You must have something back feeding, to keep the engine running when you turn off the ignition switch.