i am re-wiring my 72 halfcab and am trying to make the elec system as simple an trouble free as i can. i had points but upgraded it to a pertronix module. the 302 is freshly rebuilt but is a stock build (no hi-po parts). i have a 130amp alt from a ford Taurus i am running which is a 3G, 1 wire so no external voltage regulator anymore. both me and my buddy helping me are wondering if i need to include a ballast resistor in the system?!

any thoughts?

-cutts-

 

Check the paperwork that came with the pertronics, it should tell you if you need a resistor in the circuit, I'm guessing yes.

 

Same answer. The resistor wire is in the stock harness for the coils benifit. Removing it and putting full 12v on the coil will heat it up and shorten it's life greatly. I'm assuming you just replaced the points with the module in the dizzy.

 

Should still be there, if not look for a small explosion under the coil tower. I had a 72 with the resistor jumped out. = Boom! Check to make sure in run mode you have 9v at the coil pos wire.

 

Just noticed you are rewiring. If you need the resistor, which I'm sure you will, wire in a 1.4 ohm ballast resistor in the run mode to your coil. Centech includes one in their kit. What are you using to rewire?

 

I always use the firewall mount:



Most of the time I use DuraSpark:

 

Might want to check that pertronics ign mod carefully. Most of what I see here talks about protecting the coil from a full 12V, running voltage. I have switched out several Chebby marine point systems with Mallory Unilite systems and an MSD coil. The coil needs a resistor but the Unilite module also uses a resistor. I have never had a failure of the unilite, but have heard others did. Maybe they were were confusing the coil ballast with the resistor for the Ignition system. The duraspark does not use a resistor for the 12V feed.

 

Would you like to clarify that? Stock Ford Duraspark wiring uses a resistor wire instead of a "ballast resistor" but it does the same thing.

 

Sure thing gfw-- Maybe I will have to dig through some other diagrams, but I was using Broncoholic's diagrams when I said that. If the schematic is drawn correctly, then the feed to the Duraspark in both "run" an "start" is fed by a non-resistive 12V source. If you look at both resistor indicators on the diagrams, the resistor wire is placed between the source voltage and the coil, in the "run" position, not the Duraspark unit. The 2-pin connector that feeds 12V to the Duraspark only insures that it receives 12V in both Start and Run directly from the key switch. Now if the Resistor wire is also between the splice and the duraspark, then I am wrong, but this diagram does not indicate that.

There are several variations of Durasparks, and I almost used a Duraspark system on my Chebby marine engine to get rid of those #%&# points. Actually, when I rebuilt my Volvo engine (350 chebby), I painted it "Ford RED" instead of Volvo orange or chebby orange. I pointed that out to a friend of mine who was a chevy lover-----it actually ran better with Ford paint

Actually, later systems dont use a ballast resistor at all, only the resistor wire. Anyway, dosnt the diagram show what I said?

 

You are correct. You were refering to module feed. There is one exception though. on the older three prong module.

 

If 2 "Elder" users figure it out, its got to be right! . Although------It looks like (to me) that the R (run) and W (start) from the ign sw both feed into the 4 pin connector (pins 1 & 3) then to the Duraspark unit as a full 12V. If these pins are the actual pwr feed for the unit, then what is the feed thru the 3 pin connector (blue) to the Unit that provides both full 12V and resistor 12V to the unit? I know that one of the duraspark systems was supposed to have a built in retard function, wonder if the blue leed here is for that function. Inquiring minds want to know-------

 

sorry for the late response. had church this morning, errands, and then finally able to work on the wiring some more. i will answer whatever questions i can.

yea the paperwork says 3-4ohms but i keep reading 1.15-1.35 ohms. does it matter? i assume it does??!!

i cut the stock wiring out a few years back and am redoing all the wiring since i have added and changed so many things in the system.

i ran without a resistor for a year or so on many trail runs and it seemed fine. i dont think i had one in there at least, if i did i did not know about it. i know i will run one now. i didnt realize having one was so important.

lol spool wire and terminals from del city. i like to do things the hard way, lol. i will order one from somewhere.

this is the kind i want to run, whats the difference b/t this and a resistance wire? (they sell them at autozone if you search "ballast")

thanks for ALL the help and insight guys. this really has helped me.

-cutts-

 

Ford used a pink "resistive wire" in the stock harness. Same as using a ballast resistor, even on points setups. They used at least three different control modules w/ the blue connector being the latest and the best to use. The smaller 2 or three pin connector is the power feed for the module. Four pin to dizzy and coil for tach sensor I've never found a diagram of the internals of the modules, so I can't tell what it does and when. Broncoholic's diagrams are right and I've included another version of it. If the only thing thing you replaced is the trigger in the dizzy then all this is mute. However if you changed the coil etc, you need to match the ballast resistor to it. I wanted to change the coil to one not requiring a ballast resistor which I had, and was advised against it. So I quit trying to reinvent the wheel and just run the stock configuration with a ballast resistor. Still the cheapest, most available ignition setup. I'm by no means expert on these, but have fooled around quite a bit with them.

 

yea this is a stock coil with the xr-i module in the dizzy. i am just not sure which resistor to get as i have seen them range from .85 to 1.85 ohms. i keep hearing 1.4 so i think thats the one i am going to shoot for. i think the biggest thing is just get the coil down from 12V to keep it from overheating and apparently a small resistance is all that is needed.

yea back when i wheeled my 85 f250 i would grab whatever ign modules (with the blue connector) when i went to the j-yards. i have a pile of them now, lol. cant have enough spares!

thanks for the help

-cutts-

 

Yea, old brother and I fooled aroung with them quite a bit also. We went to MSD 6 series with the MSD "blaster" coil, (not the biggest one) and did not have to add a resistor to it, just the resistor wire in the harness. About the only thing the MSD did on our low compression stuff was to make the cold weather starts smoother (cold weather in Fl-----yea right!). Actually a bit of a problem because the MSD would damn near fire water, mixture was not as important. We decided that for the extra money over the Duraspark, the MSD was not cost effective. MSD used to make a duraspark replacement, back in the day when the durasparks had a problem of dropping out and overheating (actually start melting the potting compound).

I still think that only the coil gets the resistant 12V and not the operating power for the Unit itself. I only suggest that you check the Pertronix manual carefully, to make sure that the control unit dosnt also get some sort of resistor as well------I dont know that it does. I cant recall the wiring on my Mallory unilite (boat), but it seems that it required some resistance for the control unit as well. I did use one of the same "blaster" coils on several marine engines and because it had no resistor wiring, I had to use their supplied ballast resistor.

Anyway, sounds like you are familiar with the wiring and dont need much help. Now about My 72 bronco 302/3.03/D44/D20/9"/3.50 F=welded spider R=unknown type locker . I need to close in on how I am going to fix the doors.