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[Fronked70]

Hey everybody new to the website and would like to say thank you in advance for anyone who takes the time to read. My name is Brian and I recently aquired a datsun 521 for my son and me to work on as a project. When we got it the electrical was in pretty rough shape it had no spark but it would turn over. It had no lights, fan, and the carburator jets dripped instead of spraying. We now have lights the carb is clean and motor is getting gas. I also took my boy and hit pick and pull and found a distributor setup from a 1980 nissan changed a few things and got a proper coil replacement for the new distributor. I now have spark at all 4 cylinders. So i have spark and i have fuel but it will not start, instead it turns and periodicaly backfires out the exhaust pretty violintly untill killing the battery I smell fuel and i rechecked the spark and it was good. I also checked the timing ( as per other forums on this site) and at tdc I believe i am at 1 and from there its 1-3-4-2 counter clockwise. So im running low on ideas and any help would be greatly appreciated.

[Wide14u]

the timing is not the same on a l20 and l16 '18 so chick your timing

[Guest 510kamikazifreak]

sounds like its 180 deg out.

[wayno]

So is this engine a L16, L18, or a L20b? You want the engine at TDC with the #1 cylinder cam lobes at 10am and 2pm, some guys stick there fingers in the oil fill hole in the valve cover and feel for the lobes, personally I think for the first time take the valve cover off and look at the lobes, if it is a L20b, while standing on the drivers side of the engine compartment, the rotor should be pointing at about 4pm, if an L16/18 engine, I beleave it will point to about 10pm, which ever it is, that should be #1 plug wire, and go counter clockwise from there.

[wayno]

Oh yea, Welcome to Ratsun

[mklotz70]

I agree with the 180deg out. You need to make sure that you're on the compression stroke when you get to top dead center. Easiest way to do that is to pull plug 1 and put your thumb over the hole. You'll feel the air being pushed out past your thumb when you're on the compression stroke of cyl 1. Stop at TDC, check to make sure your rotor is lined up with the plug one tower on the dizzy cap. If all that is good....try starting fluid. But...since you said it's backfiring, the spark is not meeting the fuel and compression at the correct time. The plug wires may be a single tower off too.

[albyneau]

Welcome aboard Brian~!

[Fronked70]

Thank you so much for the responses! Im going to check the timming and see if i can get pics up.

[Fronked70]

UPDATE!!! You guys are the GREATEST seriously thank you for taking the time to respond! I took your advice and placed my finger over the cylinder 1 plug until i felt air. I then checked tdc and the rotor and let me say my plugs were not even close. I adjusted making sure it was pointed at plug 1 first and 1342 counter clockwise from there. And then like an angel turned the key VROOOM started right up with no hesitation and runs fairly smooth. So now me and my son get to turn our attention to other things. I have to say im not sure wich way to go. Im new to these vehicles so any ideas would be appricated.

[Guest 510kamikazifreak]

:thumbup:

As where to start,get the mechanicals sorted out,and itll run forever

[mklotz70]

Glad to hear you got it running :)

[Wide14u]

glad you got it going :D

[Guest kamakazi620]

Now for PICS!!!!!!!!!!!! :D :D :D

[Fronked70]

Alright so i adjusted the timing and the carb and the truck runs suprisingly well. So i have turned my attention to electrical from what i can tell my wirIng is a little diff from the schematic i found on a forum i beleive i am missing a four prong relay that should be on the passenger fender for the headlights yet the schematic does not show one also i have no break lights. I can not find the break light switch any were i found what looks like one on the fire wall but its under the gas could this be right? So I have a 1970 521 with an l18 any wiring info or pics would be extremly helpful

[DanielC]

The 521 schematics I have shows a headlight relay. The relay is at the top of the schematic, just right of the RH side marker light.

The stock relay uses 4 pins, or connections. Power comes into the relay, from the headlight switch, on the red with yellow stripe wire. This is pin 2 on the Datsun relay. Power then goes out of the Datsun relay on pin 4, a red with black stripe wire. The Red/W black goes to the two low beam headlights, one on each side.

Power on Datsun relay pin 2, internally in the relay, is also wired to the coil of the relay.

Pin 1 on the Datsun relay goes to the dimmer switch, on the turn signal lever. When the lever is moved to high beam, the relay coil is grounded, and the relay switches power from pin 4 to pin 3. Pin 3 on the Datsun relay is connected to a red with white stripe wire. that wire goes to all four of the headlights, and is high beam.

 

I believe you can use a Bosch cube relay to function as a Datsun relay, to be honest, I have not done it, but I think it can be done. Conveniently, both relays use a 1/4 spade connector.

Connect the red with white wire to pin 87 of a Bosch relay.

Connect the red with black wire to pin 87A of a Bosch relay.

Connect the light green with white wire to pin 85 of a Bosch relay.

Connect the red with yellow wire to pin 30 of a Bosch relay.

Make an external jumper, and connect pin 30 to pin 86 on the Bosch relay.

 

For the brake lights. Depending on the date of manufacturer, there is either a switch, inside the engine compartment, high above the starter, on a "T" fitting, that the brake lines run to. the switch looks like a two terminal oil pressure switch. The other option is a switch on the brake pedal bracket, close to the brake pedal stop. This switch also has two wires on it. My schematic shows the wires going to and from the brake light switch green, with a yellow stripe.

The brake light circuit up to the switch is alway hot. you have to disconnect the battery, or pull a fuse to remove the voltage from it.

Check for power to the brake light switch. Check both wires. One should have power, one should not. If you have power on one wire, jump the two wires together. The brake lights should come on. If no brake lights, check the bulbs. If you have power at the bulbs, and the bulbs are good, there is a possibility the taillights have lost the ground connection.

 

When your 521 was new, the bed, the frame, the cab, and the engine were all grounded to each other. After 40 years, corrosion may have made some of those ground connections to go bad. You need to make sure all the parts are grounded to each other again.

[banzai510(hainz)]

theres got to be a light relay. Mostly is a loose connection at the fuse box screw terminal or a bad fuse that looks good but broken inside at the ends where you can see it

However the early 521 are more like the 520 series. the later 521 are more like the 510 like for the brake light its at the pedal back side there is a switch.