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New Member and First Time Datsun Owner

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Hello Ratsun! 

I just bought a 1976 Datsun 620. got a lot of work ahead of me and am reaching out to the community to educate me on my restoration of this truck. (talking to you King Rat :P)


as it stands Ratsun.net has not had the best time with photo posting so if you want photos to help with guiding me through my many newbie questions you can feel free to pm me for my email or phone number.


the PU is a 620 longbed thats been lowered (fixing that) on 195/70/r15's the speedo is terribly off. the RPM gauge doesn't work thankfully its an automatic. then typical interior wear and damage. I have most the service manual but a mouse made its home in the glove box at some point.

I got original tires with it to re adjust to dial my speedo and actually be able to take a speed bump at 10mph...

my seat isnt orginal its a blue bench seat from a later model nissan. 


engine is an L20 with what I believe is a downdraft weber carb? not exactly sure.


current issues;


Dash wont light up but my oil light works. 


wont start all the time I think its the battery or the starter.


brake booster is dead to the world real stiff brake pedal.(could also be brake cylinder but it looks clean and maintained.


what oil thickness is best in the PNW? 5w30?


electric fan doesn't always run. cleaned connectors and re-wrapped all splicing spots, works for now.


going to try and take the lowering blocks and reverse it to a slight lift but not trying to take away from fuel economy.


missing the logo clip for my grill sadly.


got some dents and surface rust but no real damage until you get under the battery but that can be bondo'd up just fine I assume.


odometer reads 35k miles assuming its 135k miles on it.


missing tailgate handles and have bolt locks on the inside of the tailgate.


current color flat black but will repaint as white with a blacktop hood and cab top.


I'll update my findings as i go through the truck and work on it.





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If dash lights out so will the rear tail lights. Check the fuse.


New battery and new starter won't help a badly tuned engine. Set valve lash, set timing, clean/replace points, plugs, cap, rotor and wires as needed. Don't replace the coil they almost NEVER are the cause. Now adjust the idle speeds and mixture.


Check the vacuum hose is connected between booster and the intake. Half way between is a one way valve. You should be able to suck air through it from the engine side but you can't blow through it. If it's in backwards it won't work. To test if the booster is working, pump the brakes several times with the engine off. Depress the brake pedal and hold. Start engine. What you should feel is the pedal drop towards the floor slightly if working properly. 




NEVER run any oil with a 5 in it. It's too thin. 10w 30 is fine but today's oils are fazing out the ZDDP in them. ZDDP is an anti scuff additive essential for out 'flat tappet' engines. All new cars are roller rocker cam that don't need it, so oil makers are lowering the levels. Up to you to do your research on this and make an informed decision. I like Shell Rotella T (Chevron Dello 400 also) in 15w40. It's a light diesel oil with high ZDDP levels like gas engines in the 70s. I had no problem starting in below zero temperatures. I think there are several 'race engine' oild out there as well and most synthetic oil are maybe ok. I don't like synthetic oils. Too expensive and no engine goes 15,000 miles without  burning 5 or 6 quarts so what's the savings?


Lowering or raising the ride height is not going to affect the fuel economy.


Electric fans should be turned on by temp sender in the rad and a relay. If you have a switch it's subject to human error. It should be automatic.



Parts???? try an ad here... http://community.ratsun.net/classifieds/category/3-datsun-parts/?sort_key=date_added&sort_order=desc

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okay so researching tuning the engine. whats that spacer tool called you adjust against the camshaft? anything specific I should know before popping it open that  I should know? At least those I cant simply look up?

 thanks for the oil info.

My fog lights were wired in with the fan so the switch controls both. I messaged DatsunDave09 about wiring since he seemed very knowledgeable.


going to look up setting the timing, annnd newb question, what do you mean by points?



I might as well it doesn't do squat right now. Luckily our fellow member Seeker has the hook up on another booster from a parts truck!



Thanks! there a web page or info source for said stash?

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I'm not that up to speed on 620's but on a good note, I was just Given a 72' 620. So I'll be able to start going through it and figuring out plug and play upgrades, electrical issues, etc, etc. My specialty is 240Z's so most of the knowledge can be passed on from one to the other.


@76Lil Hustler

I got your email but you didn't mention What Datsun you had. I had to do the research to see what you had and if I would even be able to help.


I can do repairs but you're 200 miles away. I don't make any upgrades for the 620's as of yet. Sorry.



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Well DatsunDave any help is welcome, hoprefully having your own 620 will help with knowing what is supposed to look like. my wiring mostly just has me confused due to extras this and that. I have a flasher mounted under my steering wheel connected to nothing and a smaller flasher just dangling hooked into wire next to it so it just doesnt seem stock to me. I have a service manual but a mouse ate through some and I cant get all the answers there. 


Also 200 miles is no biggie for me. if that's how I can get my 620 back into proper shape than a 200 mile drive it is!

first I should listen to Datzenmike and tune up though.

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Thanks Racerx I saw those last night. scoooore no more half mouse chewed deciphering for me! did research and I have what I believe is a European Weber 32/36 carb with the dual draft flap things. ( I know I'm terrible, I'll learn though!)


so I adjusted the carb until there was just a pinch of room on either side when the truck hasn't ran all day. still doesn't sound right. not that I know exactly what it should sound like but I know a purr when I hear one.


I saw you can adjust your ignition by turning it and I assume I must dissasemble something to do so or does this not apply to a 76 automatic 620 with L20?

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took off my spark plug its black as night on the tip. but i already knew it was rich my tailpipe spews black gasoline smelling gunk if I rev it. this is my first time working on a car this old so its gonna be a process. my ignition control was adjusted and cleaned. there was a mark on the adjustment collar showing the middle and that is where it was set. i turned it a titch away from the engine block below the mark and it sounded better. then re adjusted the fast idle screw but haven't set my idle screw. my idle jet holder was tight as it goes so I adjusted that once but it only made things worse so I put back as I found it. 


going to adjust idle screw next but ran the engine to adjust the ignition so I should wait a bit yeah?


also! @Datzenmike I did feel my pedal drop so the booster may work? its just so stiff should I replace my brake cylinder?

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You really need a Nissan factory service manual to answer many of your questions. It pays for itself the first time you use it. For most things a '75-'77 620 manual will do but if you can get a '76. As to the holly Weber maybe find a Haynes Ford Pinto manual. Look on line for pictures to find the adjustments. It's likely somewhat similar to all Webers.

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testing photos. 1st my truck. 2nd where timing is set and 2nd B is internal of electric ignition. (complete newbie so might be wrong/getting a timing light asap) 3rd is my carb. 4th is overall engine after purchase.


my manual was eaten by mice/rats

what I do have is a  Chilton's tune up and repair manual.


open to hear a better hosting site but for now to make things somewhat functional here's links to imgbb.




https://ibb.co/cZO2nF  https://ibb.co/hJFySF


https://ibb.co/hfNpZv   weber 32/36



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You have a points distributor.


Down below the alternator is a timing scale bolted on the timing cover and the nearest pulley edge has a notch in it. Use a timing light and adjust so that the notch is at 12 degrees advance on the scale just behind it. Just loosen the distributor bolt so the distributor is easy enough to twist by hand. Check it first it might be set already. The idle needs to be about 750-850. If idling too high, mechanical and vacuum advance may give you a wrong reading. Get the idle down.



Oh yeah this is a Weber so pull the vacuum advance hose off to set the timing just to be sure.

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