Factory z24 carby fuel screw setting

[79raven]

Hey people. I will do a intro and a build thread soon, just trying to get my 1986 Navara z24 auto running before I do. Purchased the Nav for $820 with 3 months rego, its rough but relatively easy to fix.
The bloke I purchased the car off was about as good of a mechanic as my 2 year old daughter. Contact points were stuffed and in an attempt to rectify this he had mucked around with the fuel mixture screw on the carby. I have turned the screw in 22 full turns and she still runs now the points are replaced, but she stinks of fuel. Whats the factory setting for the fuel mixture screw i.e how many turns out from being screwed completely in? If I can reset it to factory then I can work from there instead of working from what the last owner had it set at.
Cheers
Raven

 

[Pinelli]

Got rid of the carby motor out of my D21 more than 3 years ago! I'll have a squiz in the manual and see what it says. I'm pretty sure they're factory set and not designed to be fiddled with though.

I'd be tempted to screw it out until it starts to idle rough, and then screw it back in half a turn.

 

[Pinelli]

Checked the manual, and after 1980, they say the mixture screw is not user changeable. You need special gear, I'm assuming an air/fuel gauge.

You can do what I said above, but be aware that if you set it too lean, you can risk running the engine hotter than it should be. Maybe screw it back in a whole turn.

Spark plugs are a good indicator as to whether the mix is good or not - a grey powdery coating usually indicates the right fuel air mix.

Check out this image.
Top right is too lean (underfuelling), middle left is overfuelling, not enough oxygen, resulting in unburnt carbon mucking things up

 

[79raven]

Sorry its been a while since I checked. Im still waiting for my build thread to be approved by admin, so started searching other sites as its been months sice I posted it and still its not approved ( or disapproved). Yeah my manual says the same thing, but I have spent plenty of time on carby's in my day and am confident I can set it right...... if I can find the screw. I have set base idle, but the fuel mixture is not right. The last guy who owned the car had played with everything that screws or turns, so maybe he stuffed around with it.
So, where is the mixture screw?

 

[Pinelli]

Google is your friend
http://community.ratsun.net/topic/16746-idle-problem/

 

[79raven]

Legend. Ive been searching the net and come up empty. My net skills suck, so thank you. Ill use that info right now

 

[Pinelli]

BTW, there are two images of carbys on that page. The first one is the older style carby where there is an actual adjustable fuel mixture. The second one is the alter model where the fuel mixture is factory set and behind a plug. If you have the second one, then hopefully the previous owner hasn't fiddled with it.

If you have no joy with this, then consider whether the carby is getting on a bit. Might be a chance to look at a replacement carby - a weber was a common option You can get them refurbished and set up specifically for the Z24, or get a second hand one off the last of the carby Falcons. I was looking at doing this before realising that my engine performance issues were not carby related, but due to a hole in a piston...

 

[79raven]

I was looking into that anyway as the carby I think could do with a rebuild. If I go a webber, how do I comply with Epa requirements i.e egr, pcv etc? They have webbers for sale on Ebay for around $500 to $600 ready to go, but with an adapter plate I should be able to get a webber cheaply.
Funny about the webbers on the Xf's, it was a common thing to put them on Lada Niva's too.

 

[user 10312]

Now that you have changed the points make sure the the ignition timing is correct. If retarded it affects the engine vacum at idle and there will have an effect on the tuning of your carby. The mixture screw will only adjust the fuel/air ratio at idle and just above after that it's running on the main jet. Not adjustable. (Apart from putting in a bigger one or drilling it out) Best way is as amentioned above, turn in till it starts to splutter then wind back out just enough to obtain a nice idle.

You can have a smell of fuel with an engine running lean to but it is a different smell more of stinky make your eyes water smell where a rich running engine will smell of raw fuel and kind of easer to breathe.
A crude way to tell is take off the air cleaner make sure and vacum lines are blocked off. Start it up and just hold a finger or two across the throat of the carb if it's running lean you hear the idle settle down and run smoother. Another trick to see how it's running up in the revs is hold the revs up say a nice steady 2000 rpm or more so it running fairly much fully on the main jet steady and repeat the same trick.
I'm sure you could make it legal with a webber carb on, having the rest of plumbing in place but there will be no real gain as where the base of the carb sits the mixture is still going down thru the same size hole. Just as better off to get the standard carby overhauled and it set up on a gas analizer.
Once fuel has gone in a carby if the vehicle has been sitting around for a while it doesn't help much at all. Diaphrams dry out and crack and dried petrol leaves a lovely white cursty gunk to block things up.

Good luck with it.

 

[Pinelli]

As far as I know, there is no EGR on the Z24. With a weber, get a falcon air cleaner housing and there should be an attachment there for PCV hose

Tappet's reminded me of something too. Under the points, in the dizzy, are some weights that help with advancing the spark at high rev. They can seize up or become stiff. Get in there and see if it moves freely. Might need some wd40 or similar.

 

[79raven]

Cheers guys. Ill definately check the weights in the dizzy. I dont have a timing light anymore as I have had newer cars now for some time, but might also do the timing by feel ( current setting marked just in case). Yes sounds rough but if she pings Ill know it not right. I have read that they love advanced timing and can comfortably hand 8 or 10 degree's before tdc.
EGR, there is heap of pipes coming from the exhaust manifold. One's like a rail that runs across the front of the engine and mounts to the front of the air cleaner, another runs across the back and then you have the pipe that runs from the exhaust manifold to the snorkel ( cant remember the name of it sorry). From memory these have to be connected to comply with epa as its a factory fitted epa item. May be wrong though.
The family car is in getting upper/lower ball joints put on today and once done the Navara will be driven till the rego runs out in December, then she's off the road for a while. Ive just spent $2900 on the family car ( tickford head, lows all round, new tyres and now ball joints), so my money to re-register and fix the Navara is gone. Should take about $500 to fix including a new windscreen but just dont have the cash. The Navara is a piece of crap thats got no balls and runs like a wounded dog, but I am going to miss her. She just makes you happy when you drive it

 

[79raven]

I told the Mrs that because the Navara is going to be off the road for maybe a while I will now install a Lexus LS400 4L quad cam lol. Id be dead in a week

 

[79raven]

Alright, checked the carby again for the mixture screw and the only screw I can see around the area shown in the pictures linked to http://community.ratsun.net/topic/16746-idle-problem/ is a screw running off a guide. Its not recessed, I cannot find any recesses in that area and I have been told the screw I am talking about is for the fuel return...... Ill try and post some pictures up of my carby. Its got a brown base plate and the car is a 1986 d21 Navara with a z24 engine.

 

[79raven]

 

[Pinelli]

Well, like I said, it is possible that the idle mixture screw is very well hidden. What yr is it?

You do seem to have a few vacuum hoses loose or not connected. Is this just because you've been fiddling?

Is there a vacuum hose running to the distributor? That too could make the engine run rough if it is missing.

Nice rocker cover

 

[79raven]

Well, like I said, it is possible that the idle mixture screw is very well hidden. What yr is it?

You do seem to have a few vacuum hoses loose or not connected. Is this just because you've been fiddling?

Is there a vacuum hose running to the distributor? That too could make the engine run rough if it is missing.

Nice rocker cover

Thanks mate. The original rocker cover had a huge hole in it when I purchased the car..... the bloke had used an old brake pad to cover it and wacked the snorkel over it to keep it down. I had some left over "ford light blue" paint from when I did some painting on my Ef and the wrecker replacement rocker cover was rusty, so waste not.
The lose vacuum hoses are off the bottom of the snorkel assembly and had to be disconnected to remove the snorkel. Vac advance is cool and works.
The car's a 1986 model. I dont know why but it seems Nissan had 2 different types of carbys on the same 86 z24 engine, one had an aluminum base and one didnt, I know that from researching carby kits but I dont know names of each style of carby. My manual said some navara's had a solenoid that controlled the air/fuel mix but I think the manual covers American and Australian models so I dont know. The only solenoid I can see is for the anti dieseling.
The main problem I have is this is the first Navara I have ever owned, hell its the first time I have seen inside a Navara's engine bay so I am lost. Its all basic mechanics but I just need almost a map to show me where things are as its all dutch to me right now. Love the car though, the Ef I have goes REAL HARD and I want more power yet the Navara is so slow and I enjoy driving it more than the Ef. The only thing thats bugging me, the Navara has had a bad life and its still hanging in there, its just things need to be attended to ( should have been fixed years ago) and while its running rough it bugs me. I dont expect a beast but just something close to how it should be running. I advanced the timing last night and she ran alot better but is still out of tune. The transmission needs a service too and that will make a HUGE difference. I have a service kit and 10L of fluid, but have had not enough time and major injuries that have stopped it getting done to date. Will be done on the weekend.
Thanks for giving a crap mate. Every bit of advise you offer will be taken on board and digested or used.

 

[Pinelli]

The American models had an electronically controlled solenoid. A little 'ecu' sat under the driver's seat or passenger seat. Not sure which. We never got it as far as I can tell.

Glad to hear the vac advance is working. That's good. Mine's an 86 as well. Love driving it.

If its still running rough, there aer a few other things to look at. You got compression readings on the pistons? New spark plugs? Does it use any oil? Make sure there aren't any vacuum leaks anywhere. New fuel filter? How rough is it? The odd miss or shaking bits off the car?

Happy to provide advice - get plenty here myself, and really like to see people looking after the old cars.

 

[79raven]

Dont have a compression tester anymore, the ex must have decided to start home mechanics when she took it....along with all my other tools. That was 4 years ago and I've got a bit purchased, but still going. My old man was a mechanic for 30 odd years and I spent alot of time on cars with him that had the same mechanics as the Navara. It brings back some memories, but also reminds me how much I forgot. Ive had injected cars now for about 10 years, so I'm a little wet around the ears but it will come back quickly
The car I got because it was cheap and I know the early Navara's are bullet proof. Turns out I love that car. The appearance actually reminds me of being 6 and wanting a Pathfinder. Since I have owned it its been another Navara thats had a hard life unfortunately. I got it for $800 with 5 months rego. Looks to have a reco head, new chain and timing cover gasket installed. The thermo housing was rusted out and had no thermostat, the dizzy cap/rotor/points/condenser were rooted, there were vac hoses not connected properly and yet she got from Sydney to the mountains. Most cars would have failed.
The plugs I cleaned and reset the gap, the leads arent the best but still in working order, new air cleaner, carby cleaned and combustion chamber flushed the best I could, new points/condenser/ cap/rotor, new thermo housing and thermostat, new coolant, oil changed, no manifold gasket leaks and thats as far as I have got. Trans is slipping when cold, but hey the fluid's like coffee. That will make a huge difference when the service is done on the weekend. Currently it just feels like its the mixture. I dont know why but that is what it feels like. The car will be off the road in December, so I will overhaul the carby then, but Id like to enjoy it before then without the rough tune. It wants to go but either hesitates, bogs or splutters. The bog down I think is because of the trans and it feels like its getting either too much or not enough fuel. Stinks a bit of fuel on cold start and you can smell fuel coming out the tailpipe when its hot but not too bad.

 

[user 10312]

A few things to check is make sure the the accelerator pump is working. With the air cleaner lid off and the engine not running. Work the throttle and you should see a little squirt of fuel down the throat of the carb. Not working, will definatlley have poor performance (flat spot) bogging down on accelerationon acceleration.

The other thing, Once the engine is up to oppertating temp that the choke flap is fully wound off. (vertical).

When overhaulling the carb check to make sure there the no slop in the throttle butterfly shaft this will induce an air bleed. On old tired carbs rebushing of the shaft is somtimes nessesary. Not just seals that come with the kit.

I can't see the mixture screw on your pics. the screw your talking about may be an air bleed screw. Alot of carbs around this era did have a little cap over the mixture screw, from memory which fails me now was usually around the bottom of the carb body and on these carbs it was on the inboard side. I think??

Also check the plumbing on the vaucm advance from the port on the carb, run a tube straight to the distributor. I know a lot of these things were routed thru a temprature sensative valve that denighned advance before the engine is at full opperating temp.

Like yourself I have forgotten more that I can remember about these old hitachi carbs and all the infamous ADR27a&b immissions bullshit that went with it but these old things can be an interesting little project to get running sweet.

 

[79raven]

Cool, mind you bypassing the vac advance is against epa laws unfortunately, but it works. Yeah auto choke works fine, fuel pours into the carby well ( I think excessively though) and both bottom butterfly's work well with a tight response. The carby kit is still definitely in the "should do" list and worst case I will find the mixture screw when its out. I am sure its staring me right in the face and when I find out where it is Ill be kicking myself.
The cars cool. I thought about maybe a 3.8 conversion or turbo, but that would defeat the purpose of me purchasing the car. I have the Ef Fairmont as a " go fast car" and the Navara will be Mr reliable and cheap to run. The engine seems like it just needs a kick in the ass. I have spoken to other who have had the z24 engines and they all say they are gutless, then you add on my auto trans and its all leaning towards granny spec's. Do they respond well to a shaved head ( raise compression)? The trans and diff ratio sits perfectly for economy and workable for every day use, just the engine performs a little lazy. I know mines running rough but its at the point were I can feel what it should be running like.
One last thing, I am not liking this "old car" talk. The car is younger than me by 7 years, its matured thank you very much ( I am joking)