High amp alternator

[Lonewolf1990]

Looking for a higher amp alternator for a 77 620 right now I’m running a 35 amp, but my radio and headlights are draining it , looking for suggestions but I want a direct swap one 

[UnderControl]

Easiest option is likely to KA swap and use KA alt with the internal regulator mod.

[datzenmike]

They don't fit very well. The stock alternator diameter is small. A larger alternator needs to be tilted away from the block and will hit the idler arm below it. I used a 60 amp from a t720 but used a Z car lower rad hose fitting to the timing cover. This lifts the lower rad hose and moves it to the rear. I think the 720 alternator mount to the block also lifts it slightly. Even then you had to slip the belt on first then position the bolts it pivots on and tighten. This keeps the alternator as close to the block as possible so you have room to tension it. A longer belt just makes it hit the idler arm.

 

Try typing ' 90 amp Saturn alternator swap. Ratsun'  on google for multiple posts on how to do this.

[Z23T]

I found this over on the Realm.

 

http://www.the510realm.com/viewtopic.php?f=2&t=11086

[Crashtd420]

I followed this post and used the 60 amp altenator... it's close but it does fit.... 

 

[datzenmike]

There may be a grease fitting in the top of the later 620 idler arms, mie did. You could grease it and take the fitting out and put in a plug. This would give another 1/8 -1/4"

[Figbuck]

I run a 60 amp IR alt listed for L20 720 trucks, in my '73 L16. It is really tight, but doable if you keep fucking with it. The first one I got out of a Pathfinder @ P 'n P, for $25, just to figure out how to lose the voltage regulator, and clean up the wiring looms.

 

'73, I don't have the radiator core "bump out" that was used in the L20 trucks, but the straight core support. I got a new ABS plastic and Aluminum radiator listed as a replacement for L20 trucks, and was able to mount it so the bottom hose outlet doesn't hit the alt/pulley/fan. Had to take a die grinder to the top of the alternator too, so the adjust arm goes in a notch. hahaha tight little fan belt, but when the junk yard alt died... an easy twenty minute swap for a new $119 one from the auto parts store. So fuggin' broke I didn't want to blow a hundred bucks on a new one... and not be able to jam it in there. Sheeit. But it works great, lights, heater/defroster, stereo, all on at the same time.

 

I read on one of these alternator swap thread where there is a 65 amp alternator available over the counter, listed for L16 510s... with air conditioning. Same physical size as the 35 amp L16 alts. But I never could find them. 

 

Why can't a bracket be modified of fabricated to run 110 amp alternator on the drivers side? Seems like a ton of room? Anybody tried it? Got OICS?? 

[Lonewolf1990]

Alright so I installed the the 60amp 1978 200sx alternator on the 620, but now my charge battery light won’t won’t shut off,  so I need a stronger voltage regulator? If I do which one do I need?

[datzenmike]

You have an external voltage regulator truck. The '78 and up Datsuns have internal voltage regulators in the alternator. This won't work on your '77.

 

Easiest thing is to return the '78 alternator for a '77.

 

Alternatively, you can modify your wiring harness to take the '78.

[Lonewolf1990]

3 minutes ago, datzenmike said:

You have an external voltage regulator truck. The '78 and up Datsuns have internal voltage regulators in the alternator. This won't work on your '77.

 

Easiest thing is to return the '78 alternator for a '77.

 

Alternatively, you can modify your wiring harness to take the '78.

The whole harness or just the regulator?

[datzenmike]

What I did on an external regulator vehicle, was remove it (the regulator) and trim the wires off of it so you have the plug with long pigtail wires. Twist the White and the Yellow wires together and the White/Black (stripe) and the White/Red (stripe) together. Solder these two joined pairs and use heat shrink tubing or wrap securely with electrical tape. You MUST solder them, twisting and taping isn't good enough. The other wires you can remove or cut very short so there's no way they can contact anything. Now just plug this back onto the harness where the regulator was. Nice and neat.

 

 

Unfortunately this mod permanently connects the choke heater relay to the on position even when the ignition is off. There's no way around this. The little relay doesn't draw much power but it will kill the battery over a long weekend. Disconnect the auto choke heater relay, remove if you like. Without power the choke heater on the back of the carburetor won't work but all it needs is a switched power supply. What I did was join the Blue choke heater wire to the Red idle cut solenoid wire right beside it on the carburetor. The ignition turns the idle cut on and off and the added choke heater.

 

I've done this on several Datsuns when I swapped in 90 or 100 amp alternators.

 

Your plug may be different but you get the idea...

 

Though covered by thick black plastic sheath, the choke wire is Blue and the idle cut Red. Join at the ends on the other side of the carburetor where they plug into the harness.

[Lonewolf1990]

41 minutes ago, datzenmike said:

What I did on an external regulator vehicle, was remove it (the regulator) and trim the wires off of it so you have the plug with long pigtail wires. Twist the White and the Yellow wires together and the White/Black (stripe) and the White/Red (stripe) together. Solder these two joined pairs and use heat shrink tubing or wrap securely with electrical tape. You MUST solder them, twisting and taping isn't good enough. The other wires you can remove or cut very short so there's no way they can contact anything. Now just plug this back onto the harness where the regulator was. Nice and neat.

 

 

Unfortunately this mod permanently connects the choke heater relay to the on position even when the ignition is off. There's no way around this. The little relay doesn't draw much power but it will kill the battery over a long weekend. Disconnect the auto choke heater relay, remove if you like. Without power the choke heater on the back of the carburetor won't work but all it needs is a switched power supply. What I did was join the Blue choke heater wire to the Red idle cut solenoid wire right beside it on the carburetor. The ignition turns the idle cut on and off and the added choke heater.

 

I've done this on several Datsuns when I swapped in 90 or 100 amp alternators.

 

Your plug may be different but you get the idea...

 

 

Though covered by thick black plastic sheath, the choke wire is Blue and the idle cut Red. Join at the ends on the other side of the carburetor where they plug into the harness.

So I’m basically cutting away the box and just soldering the wiring 

[datzenmike]

Yes. This allows the internal regulator in the alternator to do it's job and corrects the problem this causes with the choke heater relay.

 

OR...

 

Replace the internally regulated '78 and up alternator with the correct externally regulated '77 or older alternator.

[Lonewolf1990]

2 hours ago, datzenmike said:

Yes. This allows the internal regulator in the alternator to do it's job and corrects the problem this causes with the choke heater relay.

 

OR...

 

Replace the internally regulated '78 and up alternator with the correct externally regulated '77 or older alternator.

Thank u!! I just finished wiring the regulator , everything is working, just check my voltage I’m running at 14

[datzenmike]

Wow, took me forever to do it.