What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

going from an externally regulated alternator to internal?

68MUDSTUD

68MUDSTUD

OCD with shiny things
 Premium
Joined
Sep 30, 2005
Posts
9,496
Reaction score
79
Location
MT
just got my 140 amp alternator from summit the other day, and im itchin to get it on my 71 blazer that currently has an externally regulated alternator on it. How do I hook it up? It has the R and F terminals on it just like my other alternator. What all can I take off as far as wiring that I dont need anymore? I can get pics if ya need them.

thanks!
 
Last edited:
Don't have my truck here, but I think this is right. Toss the old alternator, regulator, and harness(or save them for SHTF). Then, all you really need to do is tape off the old wires out of the old external regulator and run about a #2 or #4 battery cable from the back of your new alternator direct to the positive on the battery.


More info than you need, but there's 4 wires from the old regulator into the wire harness on the core support. Ground to the body you don't need, brown wire is for the amp guage, then 2 more red(I think) - One to the fusible link to the little junction block by the battery, one spliced into the hot back to the fuse block. Also, you have a hot with a fusible link off the junction block by the battery to the fuse block on the fire wall. My fusible links were burnt up at the time, so I chose to clean up some wiring and got some new loom while I was it.
 
Sweet! Thanks man! So I wont be using the R and F terminals on my new alternator, correct? Also, do I really need 2 or 4 gauge wire from the alt to battery?
 
68MUDSTUD said:
do I really need 2 or 4 gauge wire from the alt to battery?
Click to expand...

Depending on the distance to the battery, prolly not. IMO.

I'm using 8AWG on my 140A, but it only has to run maybe three feet, from the alternator to the passenger side. IIRC, #8 is good for 150A for lengths up to six feet or so.

If you have a longer run you might want to go heavier, like #6, but I don't see #4, personally, unless your batteries are in the back.

-- A
 
Aaron probably has 10x the electrical smarts as me. But, I used the following table info and ran a 6 guage cable around 6 feet for my 100 amp - which is why I figured 4 to 2 guage for 140amp. No sense in skimping on wire size then having to worry about you're truck burn up.(says the guy who still needs to wire in the bus fuse he bought to replace the fusible links):doah:

http://www.powerstream.com/Wire_Size.htm
 
chalet2506 said:
Aaron probably has 10x the electrical smarts as me. But, I used the following table info and ran a 6 guage cable around 6 feet for my 100 amp - which is why I figured 4 to 2 guage for 140amp. No sense in skimping on wire size then having to worry about you're truck burn up.(says the guy who still needs to wire in the bus fuse he bought to replace the fusible links):doah:

http://www.powerstream.com/Wire_Size.htm
Click to expand...

LOL. I have half an EE, which almost DISqualifies me, but I used to do car stereo stuff, so I know (or used to know, anyway) a few real world things =))

As I recall, as you go from one gauge to the next you gain a LOT of area because they're scaled by diameter -- in English, #4 is half again as large as #6, and #2 is two and a half times as large as #6. (Assuming that load carrying capacity is purely a function of the cable area, which won't be entirely accurate, but should be close.)

So you figure if #6 is rated for 100A for that distance, #4 should be good for 150A and #2 for 250A :eek:

-- A
 
You must log in or register to reply here.

Latest Posts

Top Bottom