John Lees Internal Regulator Alternator Conversion

[Sharps40]

So, The Official John Lee Jr. Thread is getting fulla good stuff. Its rainin and I got good bourbon and I'm caught up on my chores so figured I'd break out some of the maintenance and conversions into individual guides.

Here we go with the Alternator Conversion.

[Sharps40]

In preparation for an HEI ignition and to prevent module frying voltage spikes, not to mention picking up from 25 amps charge to 66 amps charge for accessories, removed the old External Regulator Alternator and harness and wired Jr. up for a spanky new Delco 12SI Internal Regulated alternator. A bit of modifications to use this late model alternator but heres how it went.

Kill the battery by disconnecting it, pull both so you can run the sensing wire back to positive in order for the alternator to reulate for voltage drop in the system. (Many just hook wire one to the batt terminal of the alternator, it works but dosn't provide full voltage to the battery and can leave you perpetually under charged. Might as well do it right).



Remove the factory tape from the wiring harness, alternator to firewall to old external regulator.



Heres the parts, new 12SI alternator, Alternator pigtail for the 12 SI and a spool of 14g wire for the sensing line.



First bolt up, the pully is too short compaired to the old pully and the belt crooked. If ya ever had to pull an alternator pully with hand tools, heres a way to upgrade to the 12 SI and maintain alignment and keep the high performance fan on the pully. These new fans suck much better and the alternators run cooler than the 10SI or external regulated type. I want to maintain this feature.



See, the 12SI pully is 1/4" inch shorter than the old pulley but fortunatly the 12SI has a 1/4" boss at the bottom bolt that can be removed to move the entire alternator forward into alighment with the crank and water pump.



I saw off the protruding lower boss on the pully side of the 12SI



Some light file work and now I have the room needed to move the 12SI forward in the lower mounting bracket.



Now the bosses line up on the face and the pullies too...

[Sharps40]

Unbolt the old external regulator from the radiator support.



Cut the small red wire from the old regulator to the horn relay. Remove the black ground wire that ran between the horn relay and the old regulator. Cut the brown wire running from the dash light to the external regulator, cut it at the external regulator. Only the brown wire from the original external regularor harness will be retained. The old regulator and the rest of the old harness are no longer needed...give em to a 100 point restorer or toss em in the trash.



With the old wires that used to run from terminals 1 and 2 of the old alternator and the wires cut above, remove the unneeded external regulator harnerss.



Solder the brown wire from the dash light to the small lead (#1) of the new 12SI pigtail. Solder the sensing wire you bought to the large wire of the new 12SI pigtail, (#2)



Route the sensing wire from the alternator terminal 2 along the Batt wire and connect to the + terminal of the battery. Reconnect both posts of the battery.



Check all connections, wrap the harness and turn the key, Gen light should glow, start the motor, Gen light goes out...check voltage at the battery terminals, it should be 14.5 volts if its working right.



Thats it, go drive....

[Blue Heeler]

does this work for a 283 v8?

[Sharps40]

Should be the exact same alternator and regulator and wiring harness. There is another thread on this conversion in FAQ if you'd like to read some more.

What I can't give you information on is the alignment of the pullies/mods to the alternator mounts and brackets if needed. I suspect the 10SI with its very similar pully would be the one to most likely be a direct bolt on...the 12SI has a different pully with different distance from the alternator bracket mounts...so, might be alignment mods to do with the 12SI