Jump to content

Lookin for a little help, 79 kingcab


Recommended Posts

Hey guys, i've been lurking around the pages during the times i've been working on a few datsuns over the years. Now  I have one that i'm having some issues getting figured out. When I picked this thing up, the air cleaner was already off of it and most of the vacuum lines were unhooked. This is a 79 620 king cab and it has the smog pump on it, along with original carb. I sent the carb out to get rebuilt (needed primaries bushed anyway) and got it on, but i'm having a hell of a time figuring out what line goes where, Part of the underhood sticker is painted over. Wondering if there are any pics floating around that could give a better idea? I'm also looking for all 3 park brake cables. I figured I'd throw it in here and at the end of the week put it down in the classifieds. Any help would be awesome. I didn't realize there were so many from the portland area on here :)

Link to comment
  • Replies 19
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

rockauto.com will have your parking cables..... got both my sets from them


not trying to be a dick but a factory service manual (FSM) will go MILES in helping you figure out things like this. I have a 78' KC I'll try & remember to run off a copy of the vacuum schematic & post it here.... no promises :)


lastly.... welcome.!!! now post some pics of your truck, who doesn't like to look at pics :)

Link to comment

If you've been hanging here you know that first posts are basically intros and intros demand pictures of your Datsun.... no matter what it looks like.


There are only two hoses from the L20B carb and both are ported vacuum sources on the valve cover side down near the intake at the bottom of the carb. The one to the rear is for the running of the EGR ( exhaust gas recirculation) and needn't be connected but you can plug the outlet if you wish. The one towards the front of the carb is for the vacuum advance on the distributor and is essential for good running between idle and full throttle. 


I urge you to keep an eye out for the proper air filter housing for your truck, almost any year will do. You will need it next fall and winter to prevent carb icing. More on that later.

Link to comment

Wow, quick replies. I know I know, i'll try to snap some pictures of it today. Taking the pictures is not biggie, it's getting them over to the computer that's the issue, but i'll work on it. It's only fair.

 Looks like the front cable on rockauto is too short. I'll pull out the tape measure again and verify.

I'd love to have a fsm for it, but it's almost done already. At least the running gear and electrical. I'm doing the work on this for a guy at work who's father bought it new. Now it has 93,000 miles on it and he is wanting it to be a daily driver.  

It does have the original air cleaner housing for it, but all the vacuum lines were just unhooked from the bottom of it. I fully intend to put the original housing on it.

Off to the shop to get some pics and measurements. Thanks guys!!

Link to comment

The top air hose plugs into the intake below the carb on the driver's side. It won't idle very well with the hose off unless it's plugged. That vacuum supplies the thermostat controlled warm air to prevent carb icing..

  • Like 1
Link to comment

Those pictures sure turned out lousy, sorry, i'll try to get some better ones. The main thing that's confusing me the  most, is I have this hose fitting with 3 big and 1 small nipple coming off of it. Looking at it now, I'm not thinking it's not vacuum but just fresh air inlets from the air cleaner? There was another port up on the carb that I initially thought was a vacuum port, but must not be the case since the two on the bottom are vacuum. Thanks for the help.

Link to comment





I tried adjusting the idle tonight and didn't get anywhere with it. Backed the dashpot off all the way so it wouldn't interfere on startup and it just seemed like i couldn't get the idle below 1000 no matter what mixture and speed screw combo I tried. What is a typical starting place on the mixture screw? Maybe I am going to have to break down and buy a fsm for this thing.

Link to comment

Starting place is where it is good enough to start and run. Then turn the idle speed scew out to where it runs 800 rpm.


If you can't get it to idle below 1000, its not caused by the mixture screw.


For testing, pull all three hoses off the carb and plug the ports. Does it idle down after this?


There is also a small hose from the intake manifold to the air cleaner. Plug that or it will idle high.

Link to comment

I'm not positive if it's a california model, but looking at all the crap it has on it, I think it is. I'll double check that i've got everything plugged off. Just from memory, I think there was 5 or 6 hoses total going up to the air cleaner. I'll take a look tonight. Thanks for the help!

Link to comment
  • 3 weeks later...

So im back on the attack of the datsun after getting some other stuff wrapped up. I found  that I don't have power to the idle solenoid on the carb. (I know, duh) and that the top left fuse in the box labeled solenoid as a 10 amp was blown. So I put another 10 amp in and it blew too, go figure. So I threw a 20 amp in and turn the key on for a split second, dome light dims. Get some help from the gf running ignition switch, and now I have some power at the wire for the solenoid. So, question is, is there anything else that runs off of this solenoid circuit? Or is it just the idle solenoid. Of course I'm not going to leave the 20 amp fuse in it and start melting crap. Just wondering if someone knows offhand. Thanks.

Link to comment

Some more info, just got in from messing with it. If I unhook the solenoid wire while it's running, there is faint buzz inside the cab. I have around 7 volts on that wire that the solenoid was plugged into. If I jump the power from the chocke to the solenoid, I can get the idle set on it and it sounds good. But of course, there is the buzzing inside the cab. Maybe those two wires are supposed to be swapped? Still doesn't explain the solenoid fuse though.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.