[Hotrod_Ford]

Hi Everyone.

Would anyone be able to tell me how I would know if I need an external ballast resistor in my ignition circuit or not? I have a 302w ford v8 with points distributor. What or how do I test to ensure my electrical setup is correct. Amps or voltages at the coil or distributor?

[timothale]

Ford used a ballast resistor with 12 V points ignition systems. What Do you NEED? WE need more information, What is the car? Is the engine Swapped into older car, old or new wiring harness?

[Hotrod_Ford]

Wow what a quick response.

I'm sorry I know this was a little vague. I'm currently building a 48 Ford F3 truck. I started with a shell and I soon need to do the wiring. I bought the engine separately (not sure of the model). Unfortunately where I live we do not have the privilege of driving to the v8 shop and buying a complete harness. Al I have on the engine (for testing purposes) is my Neg and Pos cables from the battery to the earth and starter respectively, a wire to the Coil and a ballast resistor between the coil and the distributor. The ballast resistor was given to me by an auto elec and he said this is what i should use. Some diagrams do not show ballast resistor. I have a 12 volt setup.

[delawarebill]

that resistor needs to go BEFORE the coil.. so u'll have 12v to the ballast which will reduce the ''v' to the coil and not smoke test the points..

[timothale]

Most aftermarket wiring harnesses use GM Colors, I used to say the GM electrical engineers grew up with only an 8 crayon color box. They reuse the same colors in different wire sizes, (I was an engineer at Ford, had interior trim and Electrical systems for a while) The easiest thing to do is use a Ford starter relay, they were mounted normally on the inner fender panel between the battery and starter, You will need the early design with 2 small terminals, from any ford product from 57 thru the 60's, one of the small terminals hooks up to the start terminal on the ignition switch. the other terminal hooks up to the + terminal of the coil. The wire from the Run terminal on the ignition switch needs a balast resistor or correct resistance wire.BETWEEN the switch and the coil , Ford use Pink for that wire and it had High Temp rubber insulation, If the factory wire is reused ( we tried to reuse everything we could when we were broke kids trying to build a car with lawn mowing money,) the factory wire should be the original length, don't shorten it or fold it over in your harness, that can cause hot spots, burning up the wiring. I prefer the ceramic balast resistor ford started using on the 56's, It does generaate heat, should be mounted on metal away from other components, When you turn the key to the run position current flows thru the resistor , giving about 9 V power. when you turn the key to the start position, the relay sends power thru the large cables to the starter, and battery voltage thru the second small terminal to the coil. The high starting load drops available voltage but the secong wire to the coil has enough voltage to get a good spark. DO a search here on HR , Ford starter relay and you will get illustrations more info.

[timothale]

For a rod with simple components , ford pieces I like using the early Mustang diagrams try this site 1965 Mustang Wiring and Vacuum Diagrams

[EOD Guy]

Tim is spot on. If I were you I'd think about a whole vehicle wiring kit, I use the painless system and have had good luck with them. Cost is about $400 depending on how many circuits you want.

[Hotrod_Ford]

Thank you for your assistance. Great Link.