Balast resistor on Lucas coil?

[Brap_Brap]

Does the lucas ignition coil on my 390 have that resistor?

[Wedg1e]

Some do, some don't. It's a TVR

[Brap_Brap]

Wedg1e said:

Some do, some don't. It's a TVR

Would mine have it? 1987...

I want to hook my my MSD ignition but am worried I might fry something....OTOH,
right now I'd settle for it simply firing up.

[rev-erend]

Can't you just measure the voltage at startup ?

If it's fitted it will be 6V.

[Brap_Brap]

rev-erend said:

Can't you just measure the voltage at startup ?

If it's fitted it will be 6V.

That I can do, but why wouldn't it be 12v? Resistors drop amperage,
not voltage....unless my high school electricity class teacher was
BSing me.

[dickymint]

Brap_Brap said:

rev-erend said:

Can't you just measure the voltage at startup ?

If it's fitted it will be 6V.

....unless my high school electricity class teacher was
BSing me.

Go stand in the corner boy

http://www.satcure-focus.com/tutor/page2.htm

[rev-erend]

Brap_Brap said:

rev-erend said:

Can't you just measure the voltage at startup ?

If it's fitted it will be 6V.

That I can do, but why wouldn't it be 12v? Resistors drop amperage,
not voltage....unless my high school electricity class teacher was
BSing me.

It's just that I remember that coils with balast resistors are 6v .. but I might be wrong of course..

[TVR 3X]

The coils are 6V so that when cranking the engine and the battery voltage drops there is still enough voltage to give a good strong spark to start the engine. There is a direct feed to the + side of the coil from the starter motor cranking circuit.

When the engine is running and the starter motor stops (hopefully) then the circuit goes through the ballast resistor so that the coil doesn't burn out with 14.2 volts on it. The points also burn out if you leave 14.2 volts on. You can have too much of a good thing!

A 12 V coil is used without a ballast resistor and there is no connection from the starter motor to the coil but you may have trouble starting it if the battery is a bit down on volts.

Russ

[adam quantrill]

rev-erend said:

Can't you just measure the voltage at startup ?

If it's fitted it will be 6V.

Thanks Alan, for confirming this!