does my truck already have a ballast resistor

dadstan76 · #1 (**permalink**) 10-31-2009, 03:18 AM

I just ordered a Painless Duraspark wire harness and it comes with a ballast resistor. I was wondering if my truck already had one. It is a 1976 F150 4x4. It had a 360 but I put in a 390 a couple weeks ago. Here's the harness: Painless Wiring 30812 - Painless Performance Duraspark II Distributor Wiring Harnesses - Overview - SummitRacing.com

Thanks all

fmc400 · #2 (**permalink**) 10-31-2009, 02:02 PM

If your truck's wiring is original and has never been modified, it will have the ballast resistor. It's a special length of resistance wire that is integrated into the harness itself. If you crawl under the dash and look at the wire pigtail coming from the back of the ignition switch, you can see where it starts. It's a red/pink color, and has "DO NOT SPLICE" or "DO NOT CUT" printed on the insulation.

dadstan76 · #3 (**permalink**) 10-31-2009, 05:47 PM

Thanks

Do you know if I should install the resistor that comes with the harness even if I already have the wire? Would it do any harm to have two?

ctubutis · #4 (**permalink**) 10-31-2009, 05:52 PM

Quote:

Originally Posted by dadstan76

Thanks

Do you know if I should install the resistor that comes with the harness even if I already have the wire? Would it do any harm to have two?

I wouldn't install two, the factory resistor/resistance wire should lower the
voltage to factory specs, adding a second could cause problems.

dadstan76 · #5 (**permalink**) 10-31-2009, 06:01 PM

Good, the aftermarket resistor looks like crap anyways.

JimsRebel · #6 (**permalink**) 10-31-2009, 10:12 PM

Check the voltage at the coil + at idle, it should be 6-8 volts or so.
Are you using s DS2 IGN system?

dadstan76 · #7 (**permalink**) 11-01-2009, 01:45 AM

Quote:

Originally Posted by JimsRebel

Check the voltage at the coil + at idle, it should be 6-8 volts or so.
Are you using s DS2 IGN system?

Yes, I am replacing the whole harness because someone cut the heck out of the old one. It's probably the original point harness with wires added for the DS II. For example, someone cut off the connectors and wired the harness directly to the distributor.

JimsRebel · #8 (**permalink**) 11-01-2009, 11:00 AM

Most of the DS2 harness I see at the junk yard have been cut up, if I find a good one I grab it and put it on ebay (item 220479939960). They dont seem to be in high demand anymore so I dont really even look for them now, use to get $30-$40 each but now just usually one bid.
I think a lot of people are using the HEI one wire coil in cap style Dist now.