SA200 3-Wire Alternator Conversion – How I did it

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I was never quite sure that my alternator was charging the battery adequately.  Seems that the ammeter always stayed on or too near to zero.  After installing a new battery I decided to upgrade the alternator to a 3-wire Chevy with internal voltage regulation.Whatever I was able to find on the NET was less than detailed so this has became a work in progress until I am satisfied.  The job has been done and it works well.  Now I have decided to take it all apart so I can take pics for the forum.I disconnected the battery.  Well, truthfully I didn't until later when my ratchet handle arced against the + terminal of the starter solenoid.    THEN I disconnected the battery.  It is a good idea to disconnect first.Next, I removed all wires from the old alternator.  Mine was an original alternator complete with an external voltage regulator.After that I removed the alternator itself and also the lower alternator bracket.Gordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:The weather wasn't toooooo bad today so I took things apart for pics and mocked up the original lower alternator bracket for this shot. Attached ImagesGordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:For my new lower alternator bracket I modified a Chevy inline 6-cylinder alternator bracket. After measuring I cut the Chevy bracket between the outer tab & the mounting holes and spliced in ½" of 5/16" flatbar to make for a good line up of the drive belt.  For good measure I bridged the weld by shimming the backside entirely with 5/16" flatbar and welding it.  The mounting holes had to be drilled through the shim.  The extra thickness proved to be beneficial when looking for a belt to fit.I made a vee, cleaned and otherwise prepared for welding and used my Lincoln Weldpak 100 with flux core to weld it up.  A stringer root pass and a weave to fill & cap on each side makes for 100% penetration.  No matter what I did some impurities boiled up through the weld making it look rather poor.  Actually, I took a grinder to all the welds and did them again only to have the same result.The bracket mounting holes neatly line up with two bolts in the Continental engine block.  DON'T use these top two bolts LOL.  They line up also BUT the one on the right goes through into the water jacket and you will have anti-freeze all over the place.  Ask me how I know  Attached ImagesGordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:Got the new alternator for free from a scrap car.I installed the new alternator in the lower bracket and soon found out that the upper (adjuster) bracket will not fit at all.  It does not line up the hole in the alternator with the slot in the bracket.  First I tried to find a curved bracket from an old car but had no luck.  The one I was able to find didn't fit either for the very same reasonI had to modify the Continental top (adjuster) bracket so it would line up with the new alternator because it was the heaviest of the two that I had and looked like it could be made to do the job.What I ended up doing is weld a piece of 5/16" x 1" flatbar as shown in the picture.  I made a 45 deg. cut on the end of the flatbar, vee, cleaned and otherwise prepared for welding and used my Lincoln Weldpak 100 with flux core to weld it up.  This weld looked much better. The 0.035" flux core wire leave very little slag.  No chipping is required.  Just use a wire brush on it and all is well. Attached ImagesGordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:OK, bolt on the lower alternator mount, install the new alternator and check the alignment of the drive.  Not bad.  A tad off but that can be fixed by enlarging the lower bracket mounting holes a tad.  Will try and make an adjustment while I have things apart for pics.The upper bracket required a slight bend to make it line up with the alternator.  Had to make a new spacer from some scrap aluminum I had laying around.  It is only 1/16” longer than the original. Attached ImagesGordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:The old drive belt proved to be too long now.  It would get tight just as the adjustment was all used up.In order to use the original belt I would have had to bend the lower part of the sheet metal fan shroud out of the way and still would have no adjustment left so it didn't look like a good option.  Didn't really want to mess up the sheet metal so I went to NAPA for a shorter belt.Old belt number = XL 25-9490 (15/32" x 49-3/8") (12mm x 1254mm) New belt number = XL 25-9485 (31/64" x 48-7/8") (12.5/13mm x 1240mm)These belts are made for NAPA by Gates.It was not easy to get the new drive belt on.  I had to put it on the crank pulley and the alternator pulley first and then work it over the water pump pulley while turning the engine slowly with the belt.  Made sure the kill switch on the magneto is in the OFF position while doing this as my hands are in there.The adjustment is now 1/2-way and leaves lots of room for adjusting as the belt stretches.  After only running the engine for a few minutes the belt slips on and off no sweat.Gordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:Now for the fun part.  The new wiring.Connect a jumper wire from terminal #2 to the output stud of the new alternator.  This is the sensing wire that tells the internal voltage regulator how much charge to provide.I used my multimeter to determine which one was the live wire and also connected it to the stud on the back of my new alternator.  It is the red wire with the ring terminal already on it.  Just put on the stud and tighten the nut.  It connects the alternator to the hot side of the oil pressure switch.  There is power to this lead at all times. Attached ImagesLast edited by Nitesky; 12-20-2010 at 01:33 PM.Gordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:The yellow wire that used to connect the alternator to the voltage regulator is now removed and discarded as it will not be needed anymore.Gordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:The black wire that used to connect the voltage regulator to the cold side of the oil pressure switch is the field wire.  It energizes the field coils of the alternator.  It is now connected to an indicator light and the light is in turn connected to the #1 terminal of the new alternator.  There is power to this lead only when the engine is running and oil pressure has built up.  The light is supposed to add resistance to that circuit to avoid run-on when you want to shut off the welder.  I don't have to worry about run-on because the kill switch grounds out my magneto and shuts the engine off no matter what.  No spark, no run, simple.  As an added bonus, the indicator light will light up only when the alternator is not providing a charge when the engine is running.  An idiot light.  Would be a good idea to mount this light on the dash of the welder.I just left the old voltage regulator alone.  Could have removed it but it isn't in the way and has been disconnected electrically so it can't do any harm to leave it just sitting there.  Hmm, only two terminals on that regulator.  Might be no more than a simple cut-out relay anyway. Attached ImagesLast edited by Nitesky; 12-20-2010 at 01:37 PM.Gordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:Voila, the ammeter tells the story.It never used to get much past 1 or 2 amps at the best of times.  Now it shows a healthy charge. Attached ImagesGordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:Hmm, probably could have done a better job with this post but it is my first time with pics and all.MERRY  CHRISTMASGordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:Well Nitesky, that's the end of your charging system problems. Very worthwhile upgrade. Thanks for posting the details.For what it's worth, I've found some Chev I-6 brackets to be an exact direct bolt-on to Con "F" engines. Said stock un-modified Chev bracket will mount alternator with correct pulley/belt alignment, if, the alternator is equipped with correct pulley. So for those considering his swap, it may  be worthwhile to consider various available pulley and bracket options. Good Luck
Reply:Nothing at all wrong with your "first time with pics" thread and it's a nice upgrade job. Don't forget, as the battery approaches fully charged, the ammeter will register less.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Did the same upgrade on my 200, these alternators are abundant, cost less than the 1 wire yet everybody seems to use the 1 wire. The wiring is not that difficult. You can also hook some goodies into these like a light under the hood or neons if you need to really go all out for a show piece. I would imagine it would also be better if you are using and inverter. Double check your charge and battery with a volt meter, I get around 12 volts with the machine off, and when I first start it I get 14.2 volts that tapers off as the battery charges. Just a good check to see if everything is up to speed.Last edited by kolot; 12-20-2010 at 11:21 PM."Si Vis Pacem Para Bellum"Lincoln Idealarc 250 AC/DCMillermatic 251   Syncrowave 300   30A spoolgunLincoln MP210Hypertherm 45(2) LN 25(2) Lincoln Weldanpower 225 CV(4) SA200   1 short hood    SA250    SAM 400