New Truck - '71 521

[andyZ00m]

Hey there, my name is Andy, brand new to the forum as I just purchased a 1971 521 from the original owner with 59k original miles. A bit about me, mechanically inclined enthusiast who likes projects. I have a garage full of tools and experience in electrical engineering and woodworking but not a ton of classic car repair. Have a bunch of gearhead buddies who are around to help me (including one buddy who has a full lift in his private shop). Gunna need to learn some basics as well as deep dive.

 

I had a 620 growing up and have been looking for a 520 for years and years and finally the stars aligned and was able to pick this one up. Started 6 months ago with me leaving a sticky note in the window (which never works) and eventually the owner needed the cash and reached out...

 

MAIN GOAL: Have a reliable utility truck for hauling, moving, lumber, tools, equipment, etc. But also a cool classic truck to take the wife out for dinner and my dog to the park. Doesnt need to be high performance (nice to have), but would love to upgrade the things that make sense to improve drivability, reliability and longevity. I dont need to keep it stock, I plan to have this thing for the foreseeable future.

 

Known things about it:

 

-New clutch and brakes 5 years ago

-General maintenance performed diligently over its life by a shop (oil/filters/hoses, ignition adjustment, cleaning, kept covered, etc)

 

Issues/things I want to do immediately:

 

-Brakes are pretty shit. Stops like a drunken rhinoceros. Probably want to go with discs at some point in front as I plan to haul and tow.

-Still has original points ignition system. Want to move to either Pertronix or Matchbox HEI right away.

-Has electrical issues: Heater blower wont engage, popping fuses in the 4th position (10A fuse to the lighting switch assembly) when ignition is engaged, blinkers dont work but hazards do, headlights come on intermittently, dash lights dont work, windshield wipers are slow.

-Possibly move to higher performance intake/exhaust if its worth it along with other performance improvements on the stock motor.

 

Thanks for any help and I know Im at the beginning of a long adventure with this thing. I already love it, was standing in the driveway in my underwear last night just starting.

 

https://imgur.com/a/APG1xEF

 

[sick620]

you already have the best flowing highest performance intake and exhaust. If you want it to feel a bit peppier I would suggest a weber carburetor and a bit bigger exhaust pipe, electronic distributor off a 1979+ pickup called a matchbox distributor and more importantly basic maintenance plugs wires timing adjustment etc....

 

Would be wise to source an L20b out of a newer model truck as well for when this motor inevitably has problems its a straight forward install for more horsepower and torque. You will want to keep the intake and exhaust off this motor.  

 

Very nice truck and welcome! 

 

edit: tie your battery down, I recently had my 521's battery fall into engine bay, fried my whole grounding system, blew up a brake line, and welded my throttle cable wide open while driving. 

Edited November 6, 2023 by sick620

[datzenmike]

Absolutely correct of the intake/exhaust. Nissan spent a lot on designing what is basically a cast iron header. Don't waste time, money or thought an a header.....

 

 

A 32/36 Weber is also good but be aware there are a lot of knock off carburetors out there. See Pierce Manifolds for a replacement kit. Has everything needed.

 

'79 and '80 L20B engines had the EI matchbox though the '78 distributor can be fitted with an HEI module from a GM and works as well.

 

I put a car L20B into my '71 and drops right in with the L16 oil pan. Car L20Bs use the same clutch. A truck L20B needs the correct throw out bearing.

 

 

 

First thing I would do is get a FSM (factory service manual) not a Haynes or Chiltons. Try e-Bay should be under $50, and read it every day. This will pay for itself the first time you use it to fix something.

 

Brakes need adjusting possibly bleeding but adjusting is the usual cause of poor braking. Get the drums off and inspect for leaks. Wet shoes don't stop! The 521 has 4 10" drum brakes that will stop on a dime when working properly.

 

Can't follow this...

"-Has electrical issues: Heater blower wont engage, popping fuses in the 4th position (10A fuse to the lighting switch assembly) when ignition is engaged, blinkers dont work but hazards do, headlights come on intermittently, dash lights dont work, windshield wipers are slow. "

 

Turning ignition on shouldn't affect headlight fuse. They are not inter connected.

Heater is only 2 speed? how is there 4th position? Does heater fan work on the other speeds?

 

 

1/ Slow wipers are normal. Old electrical motor, wiper linkages stiff and not lubricated.

2/ If all four corners exterior lamps work on 4 way then the turn signal flasher needs replacing.

3/ Intermittent headlights is the headlight switch needs cleaning. Flush out with spray electrical cleaner.

4/ If dash lights are out check the front and rear external running lights. If they are also out see 2/ or probably the fuse.

 

 

[banzai510(hainz)]

clean fuse box ends as these are weal links on 521 cause of moisture.

 

this is not a mordern rig its 60tech if that. otherwise buy a 91 toyota with 22RE!!!!!!!!!!!

 

 

put that truck under cover or garage!!!!!!!!!!!!!!!!! sell to BIGTANKER so he can take it 5 levels up!!!!!!!!

Edited November 6, 2023 by banzai510(hainz)

[andyZ00m]

1 hour ago, datzenmike said:

 

Can't follow this...

"-Has electrical issues: Heater blower wont engage, popping fuses in the 4th position (10A fuse to the lighting switch assembly) when ignition is engaged, blinkers dont work but hazards do, headlights come on intermittently, dash lights dont work, windshield wipers are slow. "

 

Turning ignition on shouldn't affect headlight fuse. They are not inter connected.

Heater is only 2 speed? how is there 4th position? Does heater fan work on the other speeds?

 

 

1/ Slow wipers are normal. Old electrical motor, wiper linkages stiff and not lubricated.

2/ If all four corners exterior lamps work on 4 way then the turn signal flasher needs replacing.

3/ Intermittent headlights is the headlight switch needs cleaning. Flush out with spray electrical cleaner.

4/ If dash lights are out check the front and rear external running lights. If they are also out see 2/ or probably the fuse.

 

Thanks for all the responses!!

 

I have the service manual and have already started reading, its very thorough! Also found this on this forum which im going to have a large printout made for the garage.

 

Regarding the Matchbox, thoughts on this versus the Pertronix with their Coil replacement and bypassing the resistor?

 

To clarify for the quote above:

 

Heater wont turn on at all. Guess it could be the blower motor itself. 4th position was indicating the position of the fuse itself in the fuse box. I did spray some deoxit on the fuse contacts and scrubbed them down just in case.

 

Thanks for the feedback, I'll check some of that stuff on the lights and the flashers. Highly likely they need replacing. I will also spray the headlight switch.

 

The 10A fuse going through the resistor wire from battery positive to the fuse then to the lighting sw through RB wire is tripping everytime I turn on the ignition (not turning over the starter, just accessory power).

[wayno]

As mentioned, the fuse block is a weak spot in the 521, the connections corrode on the bottom side of the fuse block, I have lost my running lights/headlights(different fuses) and had to stop in the middle of the night and wiggle the wires/connections that the wires plug onto in the fuse block, the headlights and running lights would come back on for a while and then quit again, sometimes the running lights would go out when getting the headlights to work, it was a terrible issue for me, I finally gave up and replaced the harness.

 

Some soak the fuse block in Vinegar overnight and get good results.

 

As I said I gave up on the 521 harness and put a 1980 Datsun 720 wiring harness in my 1971 Datsun 521 work truck, but that is not for everyone, it is a lot of work as the gauges are not compatible with the 521 instrument cluster, and the plug for the 521 wiper motor needs to be rearranged to not smoke the 720 wiper components, also the 521 round headlights are wired differently than the 720 square headlights, that needs to be addressed also, I have done everything but it would be difficult to describe to someone how to do it all on a computer, it took years to perfect it/get everything to work like it did on a 720, oh and I used the 720 tilt column also.

[andyZ00m]

7 minutes ago, wayno said:

As mentioned, the fuse block is a weak spot in the 521, the connections corrode on the bottom side of the fuse block, I have lost my running lights/headlights(different fuses) and had to stop in the middle of the night and wiggle the wires/connections that the wires plug onto in the fuse block, the headlights and running lights would come back on for a while and then quit again, sometimes the running lights would go out when getting the headlights to work, it was a terrible issue for me, I finally gave up and replaced the harness.

 

Some soak the fuse block in Vinegar overnight and get good results.

 

As I said I gave up on the 521 harness and put a 1980 Datsun 720 wiring harness in my 1971 Datsun 521 work truck, but that is not for everyone, it is a lot of work as the gauges are not compatible with the 521 instrument cluster, and the plug for the 521 wiper motor needs to be rearranged to not smoke the 720 wiper components, also the 521 round headlights are wired differently than the 720 square headlights, that needs to be addressed also, I have done everything but it would be difficult to describe to someone how to do it all on a computer, it took years to perfect it/get everything to work like it did on a 720, oh and I used the 720 tilt column also.

 

I'm good with electronics (I build hand wired tube amps and studio equipment) and I can definitely start troubleshooting the fuse block and see if there are shorts in there.

 

I might also replace the thick "resister wire" from the battery to the contact point on the fuse bock as if that is not resisting properly, then it would be overloading the fuse every time the ignition opens the circuit.

 

Anyone know how to test if the blower motor is broken or not? I can maybe isolate it in the circuit and use a bench power supply to try powering it.

 

Also, what is the difference between DGV and DGEV carburetors?

[wayno]

1 minute ago, andyZ00m said:

 

I'm good with electronics (I build hand wired tube amps and studio equipment) and I can definitely start troubleshooting the fuse block and see if there are shorts in there.

 

I might also replace the thick "resister wire" from the battery to the contact point on the fuse bock as if that is not resisting properly, then it would be overloading the fuse every time the ignition opens the circuit.

 

Anyone know how to test if the blower motor is broken or not? I can maybe isolate it in the circuit and use a bench power supply to try powering it.

 

Also, what is the difference between DGV and DGEV carburetors?

 

The blower has a few things going on, I do not recall if you can get to the wire connector for the heater motor to bypass the switch, it is either very close to the motor(between the firewall and heater housing) or it just gets out from behind heater housing, I do not even remember where it comes out from behind housing anymore.

 

[mainer311]

Hey, welcome from a fellow enthusiast/woodworker/audiophile! 
 

Here’s a link to the schematics. I trust if you’re an EE you’ll be able to decipher them fairly easily. I printed a color version and keep it in my glovebox.

https://drive.google.com/file/d/0B5YNNQ-D8WB4emZsbmxTd21hS3c/view?resourcekey=0-8DcCQ-1sdXayKuukA0mlzw

 

Those glass fuse holders are crap. For a more reliable setup, I converted mine over to a modern ATC fuse holder. Haven’t had a problem since. 
 

You’ve hit on most of the major drivability issues:

-Disc brake upgrade

-Matchbox dizzy upgrade

-The stock Hitachi carb is complicated but works great when it’s in good shape. I honestly wouldn’t bother with a Weber DGV.

 

Truck looks great. Shame about the cracked dash.

Edited November 7, 2023 by mainer311

[datzenmike]

2 hours ago, andyZ00m said:

 

 

 

I might also replace the thick "resister wire" from the battery to the contact point on the fuse bock as if that is not resisting properly, then it would be overloading the fuse every time the ignition opens the circuit.

 

 

 

You may be referring to the fusible link. In case of a catastrophic failure such as an accident this wire will melt and shut off electrical power to the truck preventing a fire. You can replace it with a new fusible link but never replace it with regular wire. Fusible links are usually color coded for the maximum amperage they can handle and the insulation is a special plastic that will melt but resists burning.

[mrbigtanker]

I have a heater if needed. Pretty nice set up its been sitting for about 8 years. Let me know.

[thisismatt]

Nice truck!  Keep it away from all the idiots around.  Hopefully that doesn't mean you have to sell it 😛

[andyZ00m]

Thanks for the advice on the fusible link, would def replace it with the proper cable if that's the issue.

 

Things I'm going to do first:

 

-Tackle the fuse box and see if cleaning and restoring will resolve any of the electrical issues.

-Clean and service the switches in the cab to see if that helps with electrical issues

-Check flashers for replacement

-Brake job and see if there are leaks and other issues. It has a recently replaced master cylinder.

 

Thanks for all the advice! Any recommendations on a cover for a temperate climate?

 

[andyZ00m]

17 hours ago, mrbigtanker said:

I have a heater if needed. Pretty nice set up its been sitting for about 8 years. Let me know.

 

Thank you! I will troubleshoot that thing once I get through the other stuff.

[datzenmike]

Try a lemon juice and salt bath for the fuse box. Take a picture of the wiring. Wash in soapy water and/or degrease with carburetor spray then submerge the fuse box over night and rinse and dry in the morning. Fuses should never be trusted on looks alone. Replace or test them.

[banzai510(hainz)]

Heater?

just get 2 wires route from  battery to the heater fan straight on and see if motor comes on.

 

the 521 heater those rubber hose on the otherside of the heat in engine bay are hard to find.

if you could take the cover off and look at the bird cage inside might just be full of pine needle or something.

[Stoffregen Motorsports]

22 hours ago, datzenmike said:

Try a lemon juice and salt bath for the fuse box. Take a picture of the wiring. Wash in soapy water and/or degrease with carburetor spray then submerge the fuse box over night and rinse and dry in the morning. Fuses should never be trusted on looks alone. Replace or test them.

I use Krud Kutter metal etch. It's meant for metal prep, but works great on electrical connections and old fuse boxes. Spray it on, let it sit for a couple minutes, then hose it off. Just don't breathe it.

[andyZ00m]

OK, had some time today and went to my local auto parts store which is excellent and one of the dudes there is a Datsun nerd so I got a lot more info from him as well.

 

Update on general electrical issues:

 

I sprayed the light switch with deoxit and cleaned that guy up, seems to be working fine however the dash lights still dont work (more on this below).

 

The fuse that is popping is for the license plate light apparently, and there is no bulb back there and the wire is shorted to the bumper housing  for whatever reason so that's what is tripping that fuse. Will test that some more later, replace the bulb or leave it be.

 

I still haven't taken the fuse box apart and cleaned it, will do that this weekend just for good measure.

 

The heater works great! There was a mechanical blockage! (ancient leaves and shit) in the birdcage! All 3 speeds work great and the heater core works well. The rubber is even all intact. The wife is happy.

 

Regarding the indicators/dash lights not working:

 

All 4 corner lights work and flash when the hazards are on. I tried swapping the flasher units to see if the indicator flasher is faulty and when the hazard leads are connected to the indicator flasher, it still ticks but SUPER slowly. When I connect the indicator leads to the working hazard flasher, the indicators still dont work. So while the indicator flasher is likely needing to be replaced, its not the problem.

 

In the wiring diagram, there is a light relay and the guy at the parts store said that might be the issue. He said I can open it up and check if its corroded. Problem is, I cant find it in the service manual and have no idea where the damn thing is! He mentioned it could also be the indicator switch itself (on the steering column). I dont know if those are easy to source or to replace.

 

The dash lights still dont work, possible its just bulbs or related to the above but there are a shitload of little bulbs in there and seems unlikely they aren't related to the above.

 

Up next:

 

He also strongly recommended tuning or replacing the Hitachi carb, and doing the Pertronix EI with their coil and bypassing the dropping resistor. So, pretty much same stuff I planned already.

 

Brakes are next when I can get some time on the lift! The right front brake is almost certainly either not adjusted properly or the cylinder is seized as its clearly not doing its job.

 

Thanks in advance for the advice!

[banzai510(hainz)]

1 hour ago, andyZ00m said:

The heater works great! There was a mechanical blockage! (ancient leaves and shit) in the birdcage! All 3 speeds work great and the heater core works well. The rubber is even all intact. The wife is happy.

Told ya!!!!!!!!!

 

1 hour ago, andyZ00m said:

The dash lights still dont work, possible its just bulbs or related to the above but there are a shitload of little bulbs in there and seems unlikely they aren't related to the above.

think there is 2 bulbs

but if dash light dont work, the running lights usually are not working also what I notice and its the fuse

[andyZ00m]

2 minutes ago, banzai510(hainz) said:

Told ya!!!!!!!!!

 

think there is 2 bulbs

but if dash light dont work, the running lights usually are not working also what I notice and its the fuse

 
hahaa!! You were totally right on the heater. Thanks. 
 

Im realizing now I’m an idiot! That fuse that’s popping might be because the short on the license plate light, but it could also be the source of the dash lights out. Lemme check that. 

[banzai510(hainz)]

I had running lights full of wateer one time 2 but they still worked. I drilled a hole in the housing for water to drain

[andyZ00m]

Bitter sweet success and failure!!

 

I disconnected the wire that was shorting the license plate light and that solved the fuse popping problem, now I have running lights and dash lights! One tail light is out but Im sure thats a bulb.

 

NEW FUN PROBLEM:

 

Took the wife to dinner tonight in the new hoopty with a working heater and on the way back almost to the house it started losing power. Had to downshift to get it keep going another block. I was about two blocks from my house when the headlights dimmed and the motor stopped running at a stop sign. Wouldnt start, battery dead, VERY faint headlights.

 

This just a dead battery? Bad alternator all of a sudden...?

 

Seems like too much of a coincidence that I unshorted the lights and now this happened.

 

Pushed it to the curb in front of my neighbors house and walked home. My wife is quite adventurous so she was into it. 🤷‍♂️

 

NOW WERE IN IT

[Crashtd420]

Quick thing on the pertronix... check your distributor... if single points it will fit ... it dual points it will not....

[Crashtd420]

Remember with your charge system this year has a separate voltage regulator for the alternator on the fender.....

If it or the alternator is bad just convert to a later internally regulated alternator... cheaper in the long run, less to go wrong... the wiring is easy and well documented...

[Crashtd420]

Oh ya plus usually you can go from 35 amps to a 50 or 60 amp...