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1984 4x4 KC


TownDawg720

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Just picked up this 84'. Not new to datsun but this is my 1st 4x4. Love it already. Weird, i know, but i kind of enjoy and remember that 80's datsun vynal smell from the interior. This thing fits me well. Im really looking forward to this one. My last datsun was a daily driver. That sort of took some of the fun out of it because i could never have it on the stands for more than a night or two. This one though...this is the weekend getaway rig. Camping investment you could say. The best therapy for most of what ails me is some far away, isolated nature with my dogs and wifey.....via datsun 4x4...

 

 Mechanically in really great shape to start. Just needs a little TLC in a few areas. Some gaskets, lubricants, coolant, body and interior and lift. Some rust in a few spots but nothing big.

 

I'd like to set the timing this evening. It was changed to help with smog tests and has raised the idle to about 1500RPM. Prettys ure i have to advance it. Just have to run and grab some vacuum plugs real quick. So far the plan is to get some new seats in, get the valve cover and oil pan gaskets replaced, change all fluids and crank up the torsion bars to even out the front. If i can get it higher than the rear without throwing camber and caster too far off I'll make some shackles to match. Everyone here seems to get a decent adjustment out of the torsion bar so I'll try it out. Coil overs are an alternative in the future.

 

Rust, body/paint and accessories once i get it all squared away. Not going crazy with the modifications on this one. Just keeping it to a few key thigs so i can get it out to the woods ASAP...

 

Any other 720 4x4's out here in Northern California?

 

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Thanks!

I set the timing last night but never got the idle to drop significantly. Still right around 1300-1500. So far no vac leaks but the seal for the air cleaner around the neck of the carb wasn't seated properly. Fixed it bit but it had no effect as well. Im thinking choke or mixture. It aslo diesels so maybe the fuel pump or float level? Carb was rebuilt not too long ago. I need more hours in a day....

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The 720 isn't doing so hot.

Drive home from work the other day and it lost power. Could barely make it up a hill. Started the day fine, the idle was lower, around 800, and drive it to work fine. Start it to come home and it had an even lower idle almost wanting to die on me. I attempted to get on the freeway and it could barely get up to speed.

Stop at a has station, everything visually checked out, it revved fine and wasn't missing. But under any load it struggled.

First thought was it had been starving of fuel. Now IM thinking maybe it jumped timing? No smoke out of the tail pipe doesn't seen to miss when revved and Idles around 1000rpm....what do you guys think?

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The run on or dieseling is caused by the fast idle. Fix that and the dieseling will stop.

 

Fast idle....

 

Throttle cable too tight.

Idle speeds screw needs turning down.

Throttle shaft worn, throttle plate rubbing side of barrel sticking.

Choke heater not working, choke not shutting off and fast idle on because of this.

Fast idle cam dirty stuck and not shutting off.

Secondary throttle plate not closed fully letting gas and air in.

 

Air filter gasket leak not an issue. You could take the air filter housing off and would run the same.

 

I don't think it's physically possible for an L or Z series engine to jump a tooth on the cam sprocket. There's just not enough slack for this.

 

 

Lack of power but revs fine sitting could be two things...

1/ Dirt has gotten into the carb and part blocked the primary jet. However this wouldn't affect the idle and make it lower. Which makes me think.....

2/ The head gasket is blown or blowing. Perhaps between two cylinders causing a disruption. Z24 motors are well known for blowing HGs at 100k miles.

 

Things to try...

 

Check/set the valve lash. 0.013 on both on a hot motor. A tight valve will disrupt the intake vacuum or lower the compression or both.

 

Set timing to 3 degrees.

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Thank you for the info. Really appreciate it!

 

I just went out and looked over the truck. Changed the fuel filter since i had one already and thought i might start with fuel system. It started up and ran great. Drove it up and down the block with a hill included and it ran like before. Stopped the truck in front of the garage, shut it off and closed the garage door in anticipation of taking a longer test drive. It made it about 1/8 of a mile and the symptoms came back. No power. Cant give it gas now. Crawled back to the garage, pulled it in and took a step back. Just noticed the valve cover let go of the forward mounting point for the air filter housing too, leaving a nice little hole..... Ive included some pics of the carb ( or those ports normaly plugged off?) and a video of the issue.

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https://www.youtube.com/watch?v=8DsSgJy8hTU

 

 

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Thank you, i was thinking i would have to do something like that. The seller said it had been rebuilt relatively recently and the high idle was possibly related since it started after the rebuild. I'll be heading down there now to try one more little thing. Heard that the coils go bad and you can switch to see if bad coil is primary.

 

On a different note i was able to go up 2 splines on the torsion bars and it almost leveled the truck out but i dont like the camber. The tires are new and this is going to tear them up. Defintely going to get the lift kit.

 

Off to the garage to try a few things.... glad this happened at home and not out in the woods.

 

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Not enough time in a day.....

 Found 2 vac hoses with splits. Fixed those and switched the coils. No luck. Although, on initial start it ran fine again. So when cold it runs ok, after warming up briefly its back to running rough. Doesnt really rev to redline either.  Gotta grab my feelers from work and check valves tomorrow.

 

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hopefully this fixes it. youd be surprised what a rebuilt carb can do for a truck. Sounds almost like you had a leaking base gasket, my truck had the same symptoms. I am running a Weber 32/36 and it was just leaking around the base gasket. Sealed it, and night and day difference. Sounds like maybe that is why he had the idle turned up.

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Got to the last two carb sections. Not done but I did find that the anti-dieseling solenoid had the spring installed backwards causing it to slide up on the needle...which explains the dieseling. Also found a loctite looking sealant used on the float bowl gasket. It was gunking up quite a bit of the main body of the carb. My cuplrit? Not sure since it was running ok before. Glad i found these regardless. Peace of mind.

 

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has to be a vacuum leak.

 

take off the brake booster vacuum line and plug it. See if the problem still persist. If so, your brake booster leaks.

 

my money is on vacuum leak around base of carb.

 

Grab a can of starting fluid and start checking... Intake manifold, vacuum lines, base of carb, brake booster... give it a little spray on the gasket or base, and if it revs up, vacuum leak.

It runs good cold, cause the vacuum plates are closed. And it can maintain vacuum.

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Thank you for the info. Really appreciate it!

 

I just went out and looked over the truck. Changed the fuel filter since i had one already and thought i might start with fuel system. It started up and ran great. Drove it up and down the block with a hill included and it ran like before. Stopped the truck in front of the garage, shut it off and closed the garage door in anticipation of taking a longer test drive. It made it about 1/8 of a mile and the symptoms came back. No power. Cant give it gas now. Crawled back to the garage, pulled it in and took a step back. Just noticed the valve cover let go of the forward mounting point for the air filter housing too, leaving a nice little hole..... Ive included some pics of the carb ( or those ports normaly plugged off?) and a video of the issue.

2013-09-17182057_zps9c08a50e.jpg

 

2013-09-17182104_zps6865d8b7.jpg

 

https://www.youtube.com/watch?v=8DsSgJy8hTU

.

 

 

 

This appears to be a Californian High Altitude carb.It should have most of these 'vacuum' lines connected.

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Running well when cold is because the choke is on forcing a rich condition. When it warms it goes back to running on the idle and then the primary when the pedal is depressed. If the stutters when stepping on the gas then I would suspect the primary jet is part clogged.

 

If it idles high it could be that either of the throttle plates was incorrectly installed. These should not really be removed as they are hard to set on the throttle shaft properly and can rub the barrel and not close fully.

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High idle can also be from too much advance. Proper Z24 advance is around 3 degrees.

 

High idle can also be from the (cream colored) fast idle cam not dropping out of the way when warmed up.

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Thanks Poorman & Mike.

 

 I'll give it the starter fluid/brake booster check test tomorrow.

 

 As for the vacuum lines/ports-I figured they were important but then again, the truck ran OK when i bought it and drove it 2.5 hours back home. The symptoms occurred pretty suddenly. Went to work one day, started to drive home from work that same day and it lost power. I'll look for the carb specific vacuum routing. Do they look familiar? Any idea of what they need to connect to?

 

 Let me be more specific. The truck now idles ( rough idle) much lower but hesitates upon acceleration and only revs to 2k or so when it seems to hit a wall. Exhaust smells rich, is slightly smokey and dark in color. No water in the oil. Fuel pump kicks on with the key and seems to run continuously.

 

 I became aware of the throttle plate interference during the rebuild. I spent some time getting them just right. There should be no incorrect contact with the barrels.

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  • 4 weeks later...

PROBLEM SOLVED.....

 

The prolonged rich condition of the carb ( high idle ) caused the catalytic converter to burn out and clog. I mean this thing was TOAST....never seen one that bad. Fixed the cat and shes good. When i removed it and held it upright the innards literally poured out of it in chunks and streams of dust. My jaw hit the driveway...

 

Purrrrrs now. And a boat load more power. The carb, despite rebuilding, has seen better days. I think its time to go with a webber.....

 

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