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I have a 53 chevy truck and it has a 12
V coil does it need a ballast resistor ?

Depends on the coil. Some "12 Volt" coils like the one on my old 67 were hooked up to a ballast resistor. And if you look it up at say Autozone, it will tell you it is a 12 Volt coil. It is not but it is in a 12 Volt system. You need to see if it has an internal resistor. If it does, then no external resistor is needed. You can tell from the P/N on the coil if it can be read.

Ok thx

If you have a multimeter, you can check for sure. Others correct me if I am wrong.

1) measure for OHMS across the + and - side of the coil. You should get something in the area of 1.5 ohms. This is if you have a stock 6 volt coil.

2) measure for OHMS from the ignition side of the firewall mounted ballast resistor to the - side of the coil. You should get 3.5 ohms. Also the readings you would expect from a stock 6 volt coil.

3) measure for OHMS across the + and - side of the coil. IF you get roughly 4 ohms, you have what they CALL a 12 volt resistor coil. In this case you probably do not have a ballast resistor on your firewall. What this amounts to is a 6 volt coil with a built in ballast resistor.

So where does the fact that you have a 12 volt battery/system come in? Its ohms law, but what happens is, by the time you have applied 3.5 to 4 ohms to the 12 volts, you get 6 volts to the points, which is what the points need in order to last a long time and work great.

In other words, for this vintage, there isnt a 12 volt coil. You dont want one. It would burn out the points on a non-linear scale more than twice as fast. The other concern with a real 12v coil and low ohm values is the HUGE increase in current you would have going through your wiring. You dont need a fire.

Learn something new every day. I was taught (back in the mid 70s) that with a 12 volt system the ballast resistor would bring the voltage down to around 9 volts in order not to burning the points all the time.

In 1953 the truck would have been 6 volt so would not have needed a ballast resistor. But if it has been truly converted to 12 volt, then it will need one whether it is built in or not.

The advantage to an external ballast resistor would be the bypass wire used to supply battery voltage while the engine is cranking, then once running revert back to what is supplied through the resistor.

But I had never put the numbers to do the math. Thanks

Roy, your impressions are correct. Deve is blowing smoke as usual, so be careful what you "learn" from him. The correct coil for use with a Chevy 12 volt system will be a Delco-Remy, not some aftermarket piece of junk, and it will be marked "12V". It will need a ballast resistor for normal running, with a bypass circuit to apply full battery voltage during cranking. That's the way the vehicles were designed during the changeover from 6 to 12 volts, and it's still the best approach 50-something years later, regardless of all the pontificating by self-appointed "experts". The only notable change before the switch to HEI was a swap to a nickel-chrome resistance wire between the ignition switch and the coil in the mid-1960's to replace the ceramic-insulated wire-wound resistor used in the late 50's and early 60's.
Jerry

Edit: There are at least 50 of those "non-existent" Delco 12 volt coils on Ebay right now.
Jerry

I would not use a internal resistor coil because I just don't trust them and don't know how to check them. So I always get an external and use a ballast or a resistance wire if vehicle is equipped. When starting a resistance wire motor on an engine stand I just add a temporary ballast. The points don't just burn out quickly without one but over time. Some people run no ballast for years, why? I don't know. Just get what's called an E30 coil and a RU4 resistor. (O'Reilly's or equiv.). Delco-Remy coil U505. Resistor has no polarity. Let us know if you need help in wiring it up. I may be screwing you up because I'm assuming it's converted to a 12 volt system. If not, or a hybrid, stand by for revision by others before you "buy" my info. Your coil should be marked "12V" and say "internal" or "External" on it. Check it out to see the markings or a part number.

Ok I will stick with ballast resistor but Im having problems with the box that sits on top of the starter the side terminal that feeds the coil during starting has 12 v at all times there for not letting the ignition switch turn off

Hmmm. since the switch is spring loaded it should push the connector away from the terminal inside.

How do you kill you engine?

That wire will show voltage when running because it is being fed by the ballast resistor. Could it be the alternator is feeding the ignition once the engine is running? I've seen that many times on one that was converted and they didn't have the regulator wires on the alternator correct.

If the foot switch is operating OK, then as Roy says, something is wired wrong or is back feeding the terminal.

After looking at the picture of the stomp starter switch, I don't see any way that side terminal can stay energized simply because of the way the switch is made. If it has power to it, the power is coming from some where else.

I took switch off look inside it seems that the strip from the terminal makes contact with the 12 v source even if plunger is not depressed .

Could be, there is an insulator in there next to it. Maybe it's disintegrated or misplaced? I think it basically is operated by "bending" a flat metal contact. Maybe you did find the problem. I may also be remembering it wrong. Maybe this is cheap enough to try fix by replacement. That is always a good move depending on price. Certain parts are old, suspect, cheap and good to eliminate as the problem. Expensive parts take a different approach. The stomp switch is easy enough to test with continuity tester if you want. Operate it over and over and over while testing.