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620 alternator "upgrade"


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#1 daderaide

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Posted 07 November 2013 - 02:41 PM

OK, so I know I did this the hard way and should have gone with the GM one wire alternator but we all have our reasons for taking the long road. In my case, I happen to have an alternator from a '83 honda accord that was given to me with the truck and was told that it would fit. My own poor judgment led me to take the guy for his word and I didn't really look into it before I got started on the project. The GM alternator is HUGE and I don't currently have the tools and supplies necessary to fab the custom brackets and figure out what to do with the lower radiator hose. Anyway, here's what I did.

 

The alternator from an '83 accord has very similar mounting tabs to the stock 620 alternator and has a 65 amp output rather than the stock 35 amps. (top alternator is accord, bottom is stock)

DSC02102_zpsc343d025.jpg

 

To get the spacing right I just took a file to the back side of the front mounting tab. I used a pulley from an unknown ford alternator that a friend of mine had lying around. It has v-belt and a smaller fan. When installed, the fan interferes with the lower radiator hose, but all I had to do there was file down the tips of the fan blades until there was enough clearance. The last thing I did as far as fitment goes is put on a 1in longer belt. Pulley alignment is pretty much perfect and it fits perfectly in the stock mounting brackets.

 

For peace of mind and safety sake, I zip tied the lower radiator hose firmly in place so that it won't somehow come into contact with the fan since the clearance is pretty tight.

 

DSC02099_zpsde2df961.jpg

 

OK, so then there'e the wiring. I needed the connector for the alternator so I went to my local pick-n-pull and went ahead and grabbed the voltage regulator and it's connector too. It wires in place of the stock regulator almost identically. I just followed the wiring diagram for each vehicle and made an adapter plug for the new regulator. The big different is that the honda regulator needs to be "turned on" by having the charging lamp wire grounded through a resistor. In the honda, it's actually wired through the choke heater and then through a resistor to ground, but instead I used an 8ohm, 20watt power resistor from radio shack. Too much resistance and the regulator won't turn on. Too little resistance and it will over charge. The webber carb on my 620 has a choke heater that has 9 ohms of resistance which doesn't allow the regulator to turn on.

 

DSC02097_zps591ef10d.jpg

 

The only thing that is strange and I haven't figured out yet, is that the charge light in in the cab doesn't ever completely turn off. It just goes dim. Other than that it seems to work perfectly so far. The mounting that I have right now is a little messy, but it's secure for now. 



#2 datzenmike

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Posted 07 November 2013 - 02:45 PM

So what voltage do you read across the battery terminals when running???


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#3 daderaide

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Posted 07 November 2013 - 03:47 PM

14.4



#4 flatcat19

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Posted 07 November 2013 - 08:11 PM

So you upgraded to an externally regulated alternator?


You can't hang if your nuts haven't dropped...it's physics


#5 Boaty

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Posted 07 November 2013 - 08:53 PM

I sort of dislike GM one-wire alternators.
I like my Delco CS105's, per Saturn.

I think if I were to do it again, I am actually quite fond of the KA24 alternators. My 240sx alternator doesn't skip a beat even with all my kid-like stereo stuff.

The Saturn alternator swap is very well documented on this site, you might check it out and collab some information?


Steve Boatman
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71 Datsun 510 2DR --- KA24DE/5 speed
79 Datsun 620 K/C --- The damned thing WILL run again!

71 Datsun 510 Wagon - Old L20B had to go somewhere!


#6 daderaide

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Posted 08 November 2013 - 12:40 AM

It had an external regulator stock. The only "upgrade" is in the amperage output. So, ya. Not really an upgrade... But ya know... I had it laying around, so... :-)



#7 flatcat19

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Posted 08 November 2013 - 06:36 PM

I know it was sitting around. 

 

An IR Nissan upgrade is super easy to do if you get your hands on one. 


You can't hang if your nuts haven't dropped...it's physics


#8 datzenmike

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Posted 08 November 2013 - 06:42 PM

It is, but room is a problem on the 620. A larger (size) 50/60 amp from any car does not clear the idler arm below it very well. I had so little room I had to put the belt on first and then bolt the alt. in place. There isn't much swing room to tension the belt without hitting. The 720 truck has the idler arm on the outside of the frame.


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#9 dolphin

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Posted 18 February 2016 - 02:53 PM

okay, thanks for the input, I went with a 1978 datsun 200sx alternator, it's a slight upgrade to 45 amps from the oem 30, almost a direct fit, I had to get a fan belt two inches? bigger, and then had to pull the hose clamp and put it on, then reput the lower radiator hose back on, it barely fit w/o any other mods....still holding out, seems it failed, I have a double battery system, the other battery may have killed the alternator as it is an old one?   more to come, this is on an old datsun dolphin/620 camper that i just picked up



#10 maredlin1@hotmail.com

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Posted 05 March 2018 - 05:18 PM

I would like to wire a Saturn ir altenator to a 1978 ir 620, all I can find is how to put a ir altenator in a external regulator (I just need to know how to wire it). Also I've signed on with photobucket (the free membership) but I can't get the third party photos unless I pay like $300 bucks, so I can't get any photos
Thanks,
Doug

#11 DanielC

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Posted 05 March 2018 - 05:39 PM

There are a lot of Nissan alternators that will fit on your engine without messing around to get an Gm alternator to fit.  I have an alternator from a Pathfinder on one of my 521 trucks.



#12 wayno

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Posted 05 March 2018 - 05:41 PM

I would like to wire a Saturn ir altenator to a 1978 ir 620, all I can find is how to put a ir altenator in a external regulator (I just need to know how to wire it). Also I've signed on with photobucket (the free membership) but I can't get the third party photos unless I pay like $300 bucks, so I can't get any photos
Thanks,
Doug

Try Postimage, dump Photolame!!!


 

 


#13 datzenmike

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Posted 05 March 2018 - 05:43 PM

I would like to wire a Saturn ir altenator to a 1978 ir 620, all I can find is how to put a ir altenator in a external regulator (I just need to know how to wire it). Also I've signed on with photobucket (the free membership) but I can't get the third party photos unless I pay like $300 bucks, so I can't get any photos
Thanks,
Doug

 
 
 
You posted almost the same thing here ..... http://community.rat...nator-in-a-620/
 

I've tried, but I don't know how to look anything up on this site, plus I went to photobucket to try and get third party pictures, but they want $300 and some bucks even after pushing the free button. I had no idea Datsun people were so rich, but it makes sense, as you can afford to work on then. I have a 1978 Datsun 620 kc that I bought new, and it dropped a valve seat after 250,000 miles (piece of crap. So I decided to rebuild the engine. I am now attempting to put a Saturn internal regulator in my 620 that was also internal regulated. All I can find is how to convert over to external regulator. They get close but no cigar. My Saturn plug is wired to S F L P do I need to change them? If so, where do they go? Also want to keep my battery charge light.
Thank You,
For any help.
Doug



Take the advice given. This is extremely well covered in older posts.
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#14 don51o

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Posted 06 July 2018 - 05:59 PM

I put in a GM 100A two wire alt. Boy, do my electrics work!



#15 datzenmike

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Posted 06 July 2018 - 07:37 PM

Headlights don't dim at stop signs or pulse with the turn signal. The heater is a tornado and the wipers now have a high speed.


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