Ignition Balast Resistor

[campbellju]

Is it used:

A. During starting to reduce the voltage from 12V to 9V to leave more power to the starter. Bypassed during driving to revert to the full 12V to the coil.

or

B. Is bypassed during starting so the coil gets 12V and more oomph but is used during normal operation as 9V is only needed.

I've looked at the wiring diagrams and spoken to people but now I am just more confused. Other opinons appreciated.

My coil says 12V, can't think of a good reason why not to use them all the time with a bigger battery.

Cheers,
Jim

 

[OZ-Racing]

B

BALLAST RESISTOR
Definition: A resistor in the primary ignition circuit that lowers voltage after the engine is started to reduce wear on ignition components.

http://autorepair.about.com/library/glossary/bldef-047.htm

There's more:
Ballast resistor is a short piece of resistance wire or a small, usually rectangular shaped component, which is situated just before the ignition coil at the primary (+) terminal of coil.

The ballast resistor is essentially a current-compensating device made of special alloy wire. The compensating action is obtained because at low engine RPM the current flows for longer periods of time. This heats the resistor, causing less current to flow to the coil primary and improves (breaker) point life. At higher engine RPM the current flows at shorter periods of time, which lets the resistor cool and allows higher current to flow to the coil primary to produce maximum spark plug voltage.

While the engine is being turned by the starter, battery voltage is fed directly to the coil, bypassing the ballast resistor. This allows for a "hotter" starting spark.

Once the the engine starts and the starter is disengaged, the battery voltage is fed through the ballast resistor.

Seek and ye shall find

 

[campbellju]

I can't help but feel I should have been able to find that myself

This was basically my understanding but that article put it far more professionally.

Thanks OZ R for the info, the mists of the ballast resistor have cleared.

Can you think of a good reason why I shouldn't bypass the resistor all the time for the sake of changing the dizzy cap and rotor more regularily? It might be a cheaper mod than fancy aftermarket coils?

 

[OZ-Racing]

Can you think of a good reason why I shouldn't bypass the resistor all the time for the sake of changing the dizzy cap and rotor more regularily? It might be a cheaper mod than fancy aftermarket coils?

I don't see why not, but I'm no electrician.
You should just find you have to replace the ignition components more frequently (which ones you have to replace may influence your decision).

Owning an R is all about preventative maintenance, so you're probably already replacing these items only half worn

 

[campbellju]

Owning an R is all about preventative maintenance, so you're probably already replacing these items only half worn

This was basically my starting point, just replaced my dizzy cap and rotor arm after only 3000miles in case it was causing a problem I'm seeing :lol: :lol: :lol:

Its an easy mod to try and easily reversible so I might as well have a go.