YLM624AV distributor Coil with internal ballast...How to Wire???-gctid375495

[Guest]

My engine is an AQ260 with an YLM624AV distributor installed. I am rewiring the engine and I have found the ballast resistor is completely open. Rather than buy a ballast resistor, I purchased a new coil with an internal ballast resistor.

Previously the starter "R" connection was connected between the coil and the ballast resistor. With the new ignition (no points), what is the effect of connecting the "R" (purple wire) directly to the "+" of the coil? Intuitively, I say I will be providing fill voltage to the "R" terminal, as opposed to dropping some voltage across the ballast.

[2850Bounty]

A Ballast Resistor is used only when the coil uses a lighter primary side winding, and when not labeled "internally resisted".

There is no ballast resistor within the internally resisted coil.... the primary side windings are simply of a different resistance.

These will usually be labeled "internally resisted".

The R terminal circuit was to by-pass the resisted coil voltage during cranking when over-all voltage is around 10 volts. This "start-by-pass" circuit provided a full battery system voltage to the + side of the ignition coil momentarily.

This may help explain why the ballast resistor came into being.

If this was mine, here's what I'd likely do:

If I had the newer HTGR starter motor.... I'd probably go without the ballast and use the 12 volt coil.

Reason.... the HTGR starter motors do not draw quite as much cranking current, so in theory the over-all system voltage may not drop as much during cranking.

If I had the old style non-gear reduction starter motor... I'd probably use the ballast resistor and a 6-8 volt coil and the by-pass circuit.

Reason.... these starter motors do draw more cranking current, possibly dropping the over-all system voltage more so during cranking.

However, with the YLM, the by-pass circuit may not be necessary. All you can do is give it try.

As for your new engine harness:

With the AQ260 original system, there would have also been a five pin relay in this circuit.

The ignition circuit may have also been shared to provide alternator excite power. You may want to include this even if you do not need it right now.

This same ignition circuit typically powered the choke Helix Heating Element.

The Mallory YLM and YLU wiring instructions will show both resisted and non-resisted voltage supplying the triggering unit... (i.e., the Magnetic VR or Photo-Eye unit).

The two voltages (triggering unit and coil) may end up being the same, but remember that the coil's primary side winding determines it's required + (primary side) voltage.

Do not confuse triggering unit voltage with coil voltage.

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[2850Bounty]

Any luck???

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[Guest]

Thanks Rick;

I have the spec sheet with the replacement starter. The current varies 268-271 depending on sterter RPM and torque.

I will be completeing the wireing in the next few days and will post my results.