anyone know what this part is?

[Gunster89]

can this part be eliminated and if so how It came unwired one day truck wouldnt start was hidden under a po built battery box finally found the culprit and hooked it ran fine pls can anyone tell me what this part is tyvm in advance

[LostMy65]

It looks like a ballast resistor.

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[Gunster89]

Originally Posted by LostMy65

It looks like a ballast resistor.

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tyvm is this a necesary part?

[LostMy65]

What coil and distributor are you running?
Some call for a ballast resistor wired in circuit.
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[Gunster89]

I will recieve my block tomorrow I plan on running a mallory distributor not wure what coil I want yet im still learning on this stuff its going on a sbc 400 what would you recomend

[Sharps40]

Its a ballest resister. Points ignitions run at 12 volts cold to start then drop to 6 volts warm for general running. Run the points at 12 volts all the time and they just burn up.

When running electronic distributers ya should be running 12 volts all the time...i.e no resister in the cirucut

[Gunster89]

ok so since im going to run hei then remove the resister

[PoDuck]

It is a ballast resistor.

It kind of depends on which Mallory distributor you are using. If it is new, read the instructions very closely. Their Unilite distributors were notorious for going out if not connected properly, and they needed ballast resistors even though they are electronic. In fact, they needed two ballast resistors.

Rule of thumb though, if you have a separate coil, you almost always need a ballast resistor. It's not just for points type distributors as some would say it is.

Interestingly, (separate) coils are 6-9 volts. This is so that when you are cranking your engine to start it, it will still have enough power to send spark, even though the voltage drops from the battery. What happens is that when you are cranking the engine, the power is lowered in the entire system due to the amperage draw from the starter.

To make this work, the ballast resistor is disconnected while you are cranking over the engine, so whatever power your battery has left goes to the coil. Once you stop cranking, the power goes through the resistor so that your 12 volts gets dropped down to 6-9 volts, saving your coil and your points if you have them.

If you are using a separate coil, you most likely need a ballast resistor to keep from burning out the coil. If you are running points, you need it to keep from burning out the coil and the points. If you are running an HEI distributor, you need to make sure you don't run ballast resistors.

[WhippinSaw]

I bypassed the resistor on my mallory and it only lasted a few months. Had to replace the module in the distributor. If you look at the coil. it says to only use with an external resistor.

[Bearcamp]

But if one is running electronic inition how do you wire it then?

[gofastnut]

If you're running an HEI, wire it to 12v switched. DON'T run it through the ballast resistor because you can burn out the module at the worst, or at least have poor spark.

[Bearcamp]

But if you wire it to 12 volt switched it should have a fuse and take the chance of blowing a fuse?

[PoDuck]

Originally Posted by Bearcamp

But if one is running electronic inition how do you wire it then?

The starter bypass (yellow) and ignition feed (pink) wires both connect to the "From battery" or positive side of the distributor if HEI, or just to the positive side of the coil if the coil is separate.