PNW '86 Nissan 720 ST 4x4 King Cab

[Peabody]

Hi All!

 

I recently purchased a 1986 720 ST King Cab 4x4 to play with. At 138K miles, it seems to be in good condition with minimal rust and most of the options I could have hoped for (working clock included). I'm in Washington State, but by the looks of the badge on the tailgate she was born in Amarillo, Texas. I'm very excited to clean it up and work on it over time. I have minimal experience working on any cars beyond routine maintenance, let alone a near 40 year old one, so I'm looking to learn as much as I can in the process!

 

Any major failure points I should look out for in particular? I will try and do a good once over to get a baseline, but I'm going to be fumbling and researching my way through everything as I go. Being at almost 140K miles, I presume a headbolt re-torquing is due from what I've been seeing. 

 

The previous owner had just swapped to a Weber carb on the Z24i but it sat for a few years unused in a garage before selling it, and I don't think it was really run at all after the install. It idles at pretty high RPM so I think I will be messing with that trying to fine tune it soon. Today on a cold start, it got up to about 3K RPM before I tapped the gas and it settled at about 1500 RPM for 5-10 minutes before I shut it off. Never experiencing it before, it had what I assume to be pretty bad dieseling when I shut it off but hoping I can help that by getting the idle dialed in.

 

Some photos before I'd done much cleaning, but honestly it wasn't bad at all. Overall seems to be in great shape and I'm happily surprised with the state of the interior. 

*Guess I didn't include pics of the passenger side, but it's missing the door lock cylinder after somebody blew a hole in it to snatch the radio. PO welded a plate back on and smoothed it to the body at least so it's really not terribly noticeable other than not being able to unlock the door from the outside...

 

Thanks for reading 😁

 

[]2eDeYe]

Welcome, great looking truck. 
Hold on to that canopy if you can. 

[Peabody]

1 minute ago, ]2eDeYe said:

Welcome, great looking truck. 
Hold on to that canopy if you can. 

Thank you!

 

My brother in law said the same thing. Any reason other than having options/utility of the canopy? It is missing the back door so I would need to come up with a solution for that or find a replacement. Regardless, I'd not planned to ditch it right away. I'm going to see if I can rig it up out of the way in my carport.

 

[]2eDeYe]

I have thrown them away in the past, only to wish I had it later. 

[datzenmike]

Swapping to a carburetor on a Z24i is not all that simple. Look on the inner passenger side fender below the hood hinge for the engine tag. It lists the engine installed at the factory. Also is there an O₂ sensor in the exhaust manifold?

 

 

Fast idle is normal on cold start up with a carburetor with a choke. 1,800-2,200 is the norm. Maybe needs adjusting. It should retirn to normal idle RPMs (about 750) when it warms up in about 7-10 min.

 

Re-torque the head bolts on a cold engine. Loosen only one bolt and then torque to 60 ft lbs. Now do the next bolt, only one loose at a time. You can do in any order you like.

 

That's one clean 720!!!

[Peabody]

1 hour ago, datzenmike said:

Swapping to a carburetor on a Z24i is not all that simple. Look on the inner passenger side fender below the hood hinge for the engine tag. It lists the engine installed at the factory. Also is there an O₂ sensor in the exhaust manifold?

 

Fast idle is normal on cold start up with a carburetor with a choke. 1,800-2,200 is the norm. Maybe needs adjusting. It should retirn to normal idle RPMs (about 750) when it warms up in about 7-10 min.

 

Re-torque the head bolts on a cold engine. Loosen only one bolt and then torque to 60 ft lbs. Now do the next bolt, only one loose at a time. You can do in any order you like.

 

That's one clean 720!!!

 

I haven't had it sitting idle very many times, and the last time it did sit around 2,000 RPM. Today was at least 10degrees hotter, but I'm not entirely sure how I should expect it to affect the cold start.

 

Does appear to be a Z24 (I), and am I correct in assuming that's the O2 Sensor in the second pic? Side note my "Sensor" indicator light is on, which from what I read has you check the O2 sensor at 50K/100K and then unplug the connector to the bulb.

 

Thanks for the help.

 

[trjerm]

nice looking truck and that's the cleanest looking interior that I've seen on one

 

Edited July 6 by trjerm

[Sephakrid]

Wow that looks nice!

[Peabody]

Haven't adjusted the idle, but it doesn't seem to be super consistent. Today on cold start, it was idling around 1,000RPM but ended up settling at 1,500RPM after ~7-10 minutes.

Went for a drive to the store and back, and now idling at ~800RPM. Doesn't seem to be a problem at the moment so I'll address it if I need to. 

 

Anyone familiar with the flip-down dome lights? Tried setting it to "Door" setting, but appears to just be off. Randomly it came on once but hasn't again. Wonder if there's an intermittent connection I can hunt down. It works in "on" position.

[butter fingers]

awesome little 4x4 you found ! what  price did you get it for ?  a ball park figure is fine . congradulations again !! butter fingers 

[Peabody]

Thanks! Picked 'er up for about 3K

[NC85ST]

That’s one clean truck! Beautiful interior. The slide switch on the dome light can be a pain. Slide the switch back and forth several times to help clean the contacts. Could also be that it’s not getting a good ground at the door switch. 

[Peabody]

Thanks! 

 

The dome light switch seemed clean enough. Messed with the Passenger door switch and could hear the switch as it was grounding. Cleaned that up and it's working.

I expected the driver side to be the same, but remembered that's on a timer. Little bit of cleaning and it all appears to be working again! 👌

[Peabody]

This morning the truck seems to be running pretty rich and spitting out black gunk from the exhaust. I had the key in and out of the ignition in acc/on position without starting it last night as I was figuring out the lights and heard a sound that would come on for a few seconds each time. Is that the fuel pump? Makes me think about the PO Weber install and if that was done correctly. 

 

Not the first time it's done this, you can see the smaller splatter marks on the right. Wondering if it could also just be crud in the exhaust from not driving it for years.

 

[NC85ST]

It sounds like you’re hearing the fuel pump which is on the passenger side frame rail near where the cab and bed meet. Start driving it regularly and you most likely won’t see that black gunk. 

[datzenmike]

The Z24i was a throttle body fuel injection. It had a crank angle sensor rather than a regular distributor and a High pressure fuel pump. A lot of things would need to be done to convert to running a carburetor, not impossible but a lot. Most likely a replacement engine was swapped in.

[Thomas Perkins]

The second letter refers to whether it is a right-handed or left-handed carb - they're mirror images of each other. G is the right handed variant, F is for left. A DF carb has it's throttle rotating clockwise where the DG rotates counter-clockwise and the primary/secondary barrel position is of course reversed (since they are mirror 

[datzenmike]

Carburetors have chokes which force an over rich mixture and a fast idle. After about 8 min the choke should return to off and idle reduce to about 700.

 

When engine is cold take the top off the air filter and look.  Step on the gas pedal and the choke should fully close. Start and warm up the engine and take another look. The choke flap should be vertical now and fully open. So... is it???

[Peabody]

I will have to confirm for sure the operation of the carb again, but I did look at it when i first got it and it seemed to be fully closed when cold and then fully open once it was warmed up. I seem to remember it also slowly closing as it cooled down.

 

Is there another identifier I can look for to see if an engine was swapped? Would a weber carb need a fuel pressure regulator added if it was a Z24? Mine has one. 

 

Also, my carb does appear to be in an opposite orientation to others I've seen online. Hmmm

[Thomas Perkins]

 

 HERE IS MINE....https://youtu.be/u2p8yubP0eU?si=Cta23oa6MT1tdi9T

Edited July 8 by Thomas Perkins

[Peabody]

Thomas, looks like my carb orientation is opposite yours. The choke is on the side facing the middle of the truck.

[datzenmike]

2 hours ago, Peabody said:

I will have to confirm for sure the operation of the carb again, but I did look at it when i first got it and it seemed to be fully closed when cold and then fully open once it was warmed up. I seem to remember it also slowly closing as it cooled down.

 

Is there another identifier I can look for to see if an engine was swapped? Would a weber carb need a fuel pressure regulator added if it was a Z24? Mine has one. 

 

Also, my carb does appear to be in an opposite orientation to others I've seen online. Hmmm

 

A Z24i uses a high pressure fuel pump. Fuel flows in one end and out the other. The stock carburetor fuel pump is mounted vertically and the inlet/outlets are on the side. A low pressure pump would be best but a regulator would probably work.

 

My info shows this chassis built Aug '85  does that agree with the driver's door jam sticker? Close??

 

I don't think the engine number is recorded anywhere on the 720 it's just a chassis number. Your engine number can be found stamped into the top edge of the block between the two pair of exhaust pipes on the exhaust manifold...

 

 

 

 

 

[Peabody]

Door jamb sticker says 7/85, will have to get back to you on the engine number.

[datzenmike]

Mmm close. Is the engine number for your '86 anywhere on the paperwork? If it is and it doesn't match what's in the truck now then the engine was swapped.

[powderfinger]

You could also look at the ECU under the drivers seat to see if it was originally a z24i. Factory fuel pump relay is also different, bottom right under glove compartment.

Edited July 15 by powderfinger