Coil question

[ABento]

On a 34 V8 the owner has replaced the orginal coil at the dist with a modern coil mounted on the top of the manifold, this is still a 6 volt system and works very well but when the engine is warm it doesn't want to start,motor spins nicely with no stalls in between but it won't start, if you pull the truck it fires right up, the coil is marked Internal resistor and it is a 6 volt coil,I'm thinking it doesn't need the internal resitor but I'm not familar with the conversion from orginal coil to a modern coil.

[BrianCT]

34 has a wire resister under the dash. If that is still in the circuit , the voltage to the coil is too low.

[JSeery]

Check the resistance of the coil (disconnect the wires to it and check across the terminals) and also check and see if any additional external resistors are in the circuit. The ballast resistor under the dash should not be used with this coil.

[JM 35 Sedan]

I would temporarily bypass the wire wound resistor mounted behind the dash (wire & 2 alligator clips) and see what this will do for restarting the engine after it is up to normal operating temperature. If this solves the problem, jumper/bypass this external resistor more permanently.

[FlatheadTed]

It does not need the internal resistor its a 12 volt coil Ted

[VeryTangled]

Sponsored Links (Register now to hide all advertisements)

Hi Everyone, nothing to add but clarification...

Originally Posted by FlatheadTed

It does not need the internal resistor its a 12 volt coil Ted

From original post...

Originally Posted by ABento

...the coil is marked Internal resistor and it is a 6 volt coil,...

[JSeery]

Originally Posted by FlatheadTed

It does not need the internal resistor its a 12 volt coil Ted

Where does this comment come from? Do you know something that was not posted in this thread?

[ABento]

AS per instructions the resistor under the dash is out of the system.
The truck is running a6 volt coil on a 6 volt system, the only problem I can see is that the coil is marked internal resistor, I would not think that would be needed with a 6 volt system, thats what I am wondering.

[JSeery]

It needs to be somewhere around 1.5 ohms, but your not going to know anything until you check the coil to see what it is. It's volts / ohms = amps. You need to limit the current (amperage) across the point to somewhere in the 4 - 5 amp range. 6.8 / 1.5 = 4.5 amps, 7.2 / 1.5 = 4.8 amps. A higher resistance in the coil could be limiting the current/voltage.

[FlatheadTed]

The markings on coils is very vague ,its a 6V that you can run on 12V because it internally resisted .

[JSeery]

Originally Posted by FlatheadTed

The markings on coils is very vague ,its a 6V that you can run on 12V because it internally resisted .

Where are you seeing the picture of the coil Ted? Are you just assuming any internal resisted coil would be for use with 12v? I don't know the answer to that, I would want to see what the resistance was.

[ABento]

Let me put the question another way.
Do I need an internally resistored coil on a 6 volt system on the conversion from stock coil to modern coil keeping the system 6 volts.

[Henry/Kokomo]

Personally, I don't see any way around using JSeery's formula to get the right answer. What's MARKED doesn't matter. What is actually there does matter. JMO

[JSeery]

Originally Posted by ABento

Let me put the question another way.
Do I need an internally resistored coil on a 6 volt system on the conversion from stock coil to modern coil keeping the system 6 volts.

Is there a reason you don't want to check the coil? It's hard to answer your questions without knowing what you have. It shouldn't take 5 minutes to check it.

[G.M.]

Why don't you get an original coil and wire it like it should be them it would
be easy to trouble shoot?? G.M.

[ABento]

The truck isn't here at the moment and I'm gathering info so that when I do get it here I can run thru a few checks

[JSeery]

Originally Posted by ABento

The truck isn't here at the moment and I'm gathering info so that when I do get it here I can run thru a few checks

Now I see! Thanks for the clarification.