Alternator swap

[510revisited]

So I discovered my alternator was a problem. It was charging at 15 volts, and some how discharging the battery over nite. In the spirit of xmas I figured I'd just buy a new one, for shits and giggles. Well just like every project, there are hurdles. The alternator I ordered was for a 81 510. Seeing as how I have a l20b in a 69 510. Everything lines up as far as mounts go. But the pulley is now off by at least an inch or two. The old alt has no discernible numbers on it to aid in replacing it. So my question is, which vehicle should I be ordering for, a 200sx, a 720? According to wikipedia (the most trusted website, EVER) I have a l20b u95 which comes in some kind of car. I know it's a hard question to answer without seeing the parts and all, but I'm at wits end. Just need some direction...

Here is the stamp on the block showing the "u95" along with the wikipedia info

[datzenmike]

The '68-'73  PL510 uses an alternator with an external regulator. It's a fist sized metal box mounted on the passenger fender behind the battery. The later '79-'81 A10 (HL510) used an internally regulated alternator. Unless your PL510 was converted to us an internally regulated alternator this will not work electrically.

 

 

What turns the alternator isn't important, it could be a V6 for that matter. What is important is the year and vehicle for a direct replacement.

[510revisited]

My car has been converted to use an internal regulated alternator. Which is what I pulled off to replace. I understand that the motor shouldn't matter. However, I just went back to oreilly to get my core, and noticed it to does not line up with the crank or water pump pulley. From the looks of things I can modify the lower bracket to slide backwards to line things up. I guess what I'm getting at is what alternator bolts on without modifications to either the brackets on the alt or motor.... good news is the old alternator was the charging problem. I am now charging at 14.2 ish or so... 

[datzenmike]

27 minutes ago, 510revisited said:

My car has been converted to use an internal regulated alternator. Which is what I pulled off to replace. I understand that the motor shouldn't matter. However, I just went back to oreilly to get my core, and noticed it to does not line up with the crank or water pump pulley. From the looks of things I can modify the lower bracket to slide backwards to line things up. I guess what I'm getting at is what alternator bolts on without modifications to either the brackets on the alt or motor.... good news is the old alternator was the charging problem. I am now charging at 14.2 ish or so... 

 

So the core, the original alternator doesn't line up either??? How is that?

 

Well the '81 engine is a Z20S so that may be the difference. If you need an L series engine alternator. The '79 A10 HL510 was equipped with an L20B and internally regulated alternator. The '78 and '79 S10 200sx alternator (also for an L20B) should be about the same.

[Ranman72]

pictures of the old alternator and possibly pictures of the bracket might help distinguish what you have 

[510revisited]

16 hours ago, datzenmike said:

 

So the core, the original alternator doesn't line up either??? How is that?

 

Well the '81 engine is a Z20S so that may be the difference. If you need an L series engine alternator. The '79 A10 HL510 was equipped with an L20B and internally regulated alternator. The '78 and '79 S10 200sx alternator (also for an L20B) should be about the same.

Again, this motor was swapped in by the previous owner. I have done nothing except add my holley sniper and bluetooth dizzy. Here is a pic of the alignment of the pulleys. I think, just to ease my mind, I may fab up my own bracket. I compared the two alternators. They are identical as far as mounting goes. Its baffling to me too. Actually it is more frustrating than anything. Everytime I get a win, I get a loss. 

Here is a pic of the alignment..its hard to tell, but if you look at how the belt comes off the water pump pulley you can see it comes off at an angle... 

[datzenmike]

Yeah it should be back and that adjustment strap on the front of the case.

 

Can you take a picture looking up from underneath? Showing the mounting to the block???

[510revisited]

42 minutes ago, datzenmike said:

Yeah it should be back and that adjustment strap on the front of the case.

 

Can you take a picture looking up from underneath? Showing the mounting to the block???

So, I just went to o'Reillys again. The part number for the alternator is the same for a 200sx, hl510 79 and 81.. I think my mount on the bottom is really the issue. I will get a pic a.s.a.p.

[banzai510(hainz)]

Be honest it looks OK to me. maybe use a 510  4 bladed fan with its pulley???

Mine is actually worse in my 521 as the mount it wearing out. with the pass thru holes oblonging.

 

for the battery drain hook the choke relay is did connected but that should have been done years ago by the previous owner. Sinced this is a later Alternator you should have the jumper wires installed at where the old volt regulator connector. Most popel use a the old volt reg plug and short it there incase you want to go back to stock

 

another thing if you go thru with all this to inject this motor and pout a O rileys rebuild in there don't make sense.

 

Rockauto has NEW alternator and I have gotten better results from them after my last fiasco with Autozone O rielys Alternators. 8/9 months max.

 

 

as mike said about the adjustment ARM that should be obvious which side it goes as where the tension of the stress is but I cant remember which side it goes on as I use a Turnbuckle system now. I got tired of them coming loose

[datzenmike]

Looks like the alternator needs to go back about the width of the mounting arms at the block.

 

 

 

 

[banzai510(hainz)]

If I remember right my alternator arm landed right on top of the alt above the hole

but really the alternator is not going to move once you put the lower bolts in as its a tight fit as by time the l20s came out they had the nicer bigger bolts thru the mount. it not going to move anything just the adjustment arm might have more tension going from front to back or vice versa

[bilzbobaggins]

4 hours ago, 510revisited said:

Again, this motor was swapped in by the previous owner. I have done nothing except add my holley sniper and bluetooth dizzy. Here is a pic of the alignment of the pulleys. I think, just to ease my mind, I may fab up my own bracket. I compared the two alternators. They are identical as far as mounting goes. Its baffling to me too. Actually it is more frustrating than anything. Everytime I get a win, I get a loss. 

Here is a pic of the alignment..its hard to tell, but if you look at how the belt comes off the water pump pulley you can see it comes off at an angle... 

 

 

I would also put a lockwasher and  nut on the backside of the top bolt.  These damn things buzz so much.

[510revisited]

4 hours ago, bilzbobaggins said:

 

 

I would also put a lockwasher and  nut on the backside of the top bolt.  These damn things buzz so much.

Good looking. Will consider that when I finish it.. 

 

7 hours ago, 510revisited said:

So, I just went to o'Reillys again. The part number for the alternator is the same for a 200sx, hl510 79 and 81.. I think my mount on the bottom is really the issue. I will get a pic a.s.a.p.

Heres the pics of the mount

Looks like I could grind down the mating surfaces, but that would likely weaken the one tab. I could slot the holes. However, I'm not one to modify oem parts. It's kinda a pet peeve. I will when necessary, but at one point in its life, this motors original alt lined up from factory. M almost sure of it. I'm up for suggestions, but I think I'm gonna fab something.

5 hours ago, banzai510(hainz) said:

Be honest it looks OK to me. maybe use a 510  4 bladed fan with its pulley???

Mine is actually worse in my 521 as the mount it wearing out. with the pass thru holes oblonging.

 

for the battery drain hook the choke relay is did connected but that should have been done years ago by the previous owner. Sinced this is a later Alternator you should have the jumper wires installed at where the old volt regulator connector. Most popel use a the old volt reg plug and short it there incase you want to go back to stock

 

another thing if you go thru with all this to inject this motor and pout a O rileys rebuild in there don't make sense.

 

Rockauto has NEW alternator and I have gotten better results from them after my last fiasco with Autozone O rielys Alternators. 8/9 months max.

 

 

as mike said about the adjustment ARM that should be obvious which side it goes as where the tension of the stress is but I cant remember which side it goes on as I use a Turnbuckle system now. I got tired of them coming loose

Well, when it goes out in those predicted 8/9 months, I'll look into that. I completely removed what is I believe to be said choke relay. I even noticed that I can remove all my NEGATIVE connections that are from the car. I.e. not the negative wiring for the injection or distributor, and noticed it still runs, and starts... in my head that does, and doesn't make sense... the new distributor has 3 wires. Batt ground, coil neg, coil pos. I did however hook things back up to the coil, but in retrospect, if the relay is disconnected, then the neg wires at the coil are not needed, correct? Thanks for all the help. Wish I could buy you guys a beer

[banzai510(hainz)]

Don’t know what you mean by getting rid of negative connections

[Ranman72]

looks like the wrong mount to me should look more like this 

[Ranman72]

look through this swap upgrade 

your bracket is for an upgraded possibly non datsun alternator http://www.the510realm.com/viewtopic.php?f=2&t=11086

 

[datzenmike]

Those are both Datsun (3 bolt) L20B mounts. I've used both.

[banzai510(hainz)]

510revisited looks more like a truck alternaot mount which is similar to the 521 stamped welded sheetmetal mount.  So if those bolts go loose the alternator will shift angle

The car mounts.  the alternator is in t a fixed precies position and should not angle out of position

[510revisited]

On 12/27/2019 at 4:29 PM, 510revisited said:

I even noticed that I can remove all my NEGATIVE connections that are from the car. 

Should have clarified. By installing the fuel injection, and new dizzy, I was able to unplug all the negative wires off the coil, meaning the original datsun wires. I only two wires on the negative side of the coil now. From the dizzy and the efi..