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Alternator Upgrade


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So I have my 1968 510 Wagon, and quite a lot of electrical drawing devices in it. Upgraded headlights, big stereo, and a few other things, and when I have my lights on, indicator on, stereo playing, and foot on the brake pedal (brake lights on), the voltage gets so low that the car either stalls, or has a horrible idle forcing me to keep my foot on the gas to keep it charging. While driving this usually isn't a problem, as my gauge shows around 14-16 volts depending on RPM.

My question is, what should I replace it with? Especially if I plan on running more things off the engine. I'm pretty sure right now it has a stock 35 Amp unit, though I am not 100% sure due to its strange engine (L20b bottom end with L16 head).

I would like a bolt on sort of deal if possible or one that already has a conversion kit. I don't have the tools or ability to make myself a bracket I trust.



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Some people do a saturn alt swap, a GM 1 wire swap etc.


I would do a nissan swap, get a KA alt for a hardbody pickup. All you have to do is change the plugs for the alt hookup, and also you will need to make two wires with spades on all 4 ends, and disconnect the voltage regulator and plug in those spade connectors. then it will be ER bypass for IR alts.

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68 wire is the worst be careful and they use the older plug harness stuff.


persoanlly get rid of the stereo! and maybe find a 50ampr alternator for for a EZ upgrade if the T connector is still used in the back. I lnow early 521s can have a asortment of connector styles.

68 510 I barely remeber.


also if you have a L16 block the bolt holes are different sizes unless you have a L20 in there then they use bigger alternator bolts in motor and the bracket


olddatsuns.com watch my vid



i think order like a 76 77 L20 alternator from a car like a 610/710 external reg. They should be cheap from your O rileys or whatever.


If your L20 came from a truck it could be a smaller 35amp. cars had the bigger one. but dont run highbeams and heater on at idle. even a 50amper wont hold up. you just got to know when to use the power

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Think a 60 amp will be enough? And is that a bolt on?



For your situation, you said upgraded stereo. What all does that include? Big amp, sub, lots of speakers etc?


The 60 Amp bolted straight onto my A15 with no problem. No wiring or anything. I have some of the symptoms you have though. With high draw (headlights, brakes etc) I do notice it idles down, but not enough to stall it or idle rough.


The 60 amp I got from Autozone for $50 (not counting core). P/N 14303. Came off a 280ZX. Spent all night at work in the zone to find it and make a match to the stock.


Going from 35 to 60 should be a noticeable difference.

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Early ones like yours could be 33 or 35amp. '71s were 35 but there were optional 50 amp available. The 710 and 610 had 50/60 amp that should fit and would be similar to the same year Z car. After '77 they were internally regulated.


There should be a sticker on the side get the numbers and I can give the output.... but likely 35 amp. Look for ones that says LT 150 or LT 160

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Alternators have a maximum speed that they can be spun. Because the Datsun engine is capable of turning 6500 or 7000 RPM quite easily, the alternator is not ran as fast as a typical V8 when the engine is idling.

A higher amp alternator will help with charging at an idle, with a bunch of accessories on, but may not cure the problem completely.

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Yea, there is no way I'm getting rid of my stereo! It is usually alright, since I don't have everything on at once, and if I need to there are things that I can cut out such as turning off the stereo and one set of lights, but thanks for the help everyone! I'm gonna check it out soon, since I'm pretty sure its a 35 amp and hopefully get a 60+ amp alternator. Since that is almost double and right now the stock 35 is almost making it, I think it should be enough.

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Just remember that Datsun changed over to internal regulated alternators for the '78 model year cars and trucks and they will not work on your external regulated car.


As stated earlier you can fairly easily convert your '68 to work on the newer style which are probably easier to find.

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  • 2 years later...

I usually run a subaru 65 or 80 amp t plug Hitachi from a loyal/gl, direct bolt on. just scored a 125amp off a vg pathfinder with ac also direct bolt on just have to change the plug

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