http://www.team.net/www/rootes/sunbeam/alpine/mk1-5/techtips/altconv.html

The connections are labeled R and L in that schematic.  He says L stands for load, but it isn't connected to a load; it's connected to the charging indicator lamp, so I think the L just stands for Lamp.  And yes that one is connected to the field.  Besides lighting an indicator, the L terminal serves to "tickle" the field with current from the battery to help the alt get powered up.  You can run an alternator without that connection, but you might have to rev it up a little more before it starts putting out current.  It's sometimes called a "one-wire" hookup when you do it that way.

The connection he calls R is the voltage sensing circuit.  I guess it's called S for "switch" or for "sensing" on your alternator.  That one is required for the voltage regulator to function.  It goes to the voltage regulator, which controls the field current to keep the alternator putting out the right voltage.

Thanks again!

  Hello I use a 1970's ford alt and a 5.5 hp B&S engine.You need an external regulated alt, only dont hook up a regulator,this way you squeeze out every bit of energy it can give.I run mine about an hour at a time.Unregulated you get 18 vdc @ 40 amps, at a fast idle.If you regulate it with an auto regulator,it cuts down to only 10 amps after about 10 minutes run time.

On the back of the alt you hook the grnd termnial to the grnd post on the battery....

Then run a wire to a on/off switch, over to the Fld on the alt..then from the switch to the Batt terminal on the back of the alt.This gives the field full voltage from the battery....

Now a wire from the batt terminal on the back of the alt, to an auto dc ampmeter.The other side of the amp meter goes to the pos post on the batt.

The "s" stator doesnt hook to any thing.....

If you want a voltage guage put this between the on/off swaich and the frame ground...

 All wires must be hooked tight,at this amp flow a loose wire or guage will melt...