Resistance wire
Thread Starter
|
Freshman User
Joined: Dec 2015
Posts: 26
Likes: 0
Resistance wire
I am installing a Pertronix ignition on my 70 F-100, 302. I read some of the other posts about installation and of bypassing the resistance wire, it seemed easy. When I went to tap into my ignition switch I saw that instead of the red/green wire sharing the post with the pink wire, it was blue. I was wondering if color codes change, or if I can run a jumper off of the resistor wire directly to the positive side ? When I look at the color codes it says that the light blue wire is for the turn signal. Thanks for the help.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Part of the problem is the wiring could have been modified by previous owner. You could check resistance, from the ignition switch to the solenoid. The resistance wire should measure 1.20 to 1.30 ohms, right in there, a lot higher than conventional wire. Can bypass or replace, directly to + terminal coil with a heavy gauge wire.
Thread Starter
|
Freshman User
Joined: Dec 2015
Posts: 26
Likes: 0
Resistance wire
Thanks for the reply. I think I may just take the ignition switch out, pull the pink wire out, and run a new wire in place of the pink wire. I have another 70 wiring harness, and the blue wire is there in place of the red/green. The truck was an early build, maybe a 69 part?
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
I think it's better to use a coil that is OK with 12+ volts, like their Flamethrower 1.5 ohm. You can measure the coils you already have. All coils have some resistance, it's just a matter of how much.
The ballast resistor was used to further lower the current going through the points. If you've gotten rid of the points as is the case here, the ballast can go bye bye assuming the overall resistance isn't too low. Pertronix says 8 amps maximum current for the Ignitor. This is what you're looking for, and why.
14.5 volts divided by 1.5 ohms = 9.6 amps, but, coils are not "ON" 100% of the time. This is what dwell is all about. So the continuous current draw is around 6 amperes rounded up. Then there is the resistance of the primary circuit itself on top of that. So we're in good shape, with a little reserve for safety.
The ballast resistor was used to further lower the current going through the points. If you've gotten rid of the points as is the case here, the ballast can go bye bye assuming the overall resistance isn't too low. Pertronix says 8 amps maximum current for the Ignitor. This is what you're looking for, and why.
14.5 volts divided by 1.5 ohms = 9.6 amps, but, coils are not "ON" 100% of the time. This is what dwell is all about. So the continuous current draw is around 6 amperes rounded up. Then there is the resistance of the primary circuit itself on top of that. So we're in good shape, with a little reserve for safety.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Measure it. Don't guess, from some back of the envelope math it looks to me that a coil is "ON" 60% of the time on a V8 anyway. I have some "Electronic Ignition Only" marked coils, and a stock mustard top that I should measure primary resistance. They should work fine with no ballast if the primary resistance is reasonable, which it might not be.
Thread
Thread Starter
Forum
Replies
Last Post
Blue and White
1973 - 1979 F-100 & Larger F-Series Trucks
19
Aug 31, 2025 06:49 PM
billybodaddo
1967 - 1972 F-100 & Larger F-Series Trucks
2
Oct 25, 2012 10:44 AM
dgrant09
Electrical Systems/Wiring
2
Mar 16, 2008 11:44 AM
70T351W
Electrical Systems/Wiring
3
May 1, 2006 11:21 PM
