720 Carburetor Tutorial with Pictures

1980-1986 Datsun 720 forums. All 720-specific topics and discussion can be found here.
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delcena49
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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Tue Apr 09, 2013 6:39 pm

Image,Image,Image,Image,Image,Image,Image,Image,Image

Like I said it was a work in progress. The picture of the engine was taken today 4-9-2013. I am trying to redo the vacuum hoses myself. So you can see why I NEED HELP PLEASE.


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fastboatman29212
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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Wed Apr 10, 2013 5:40 am

You never said wether you looked at the DIY section where there is a post that explains where the vac lines go. You want help. But first go there and see what is already available.

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delcena49
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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Thu Apr 11, 2013 6:14 pm

I clicked on the link but no diagram.

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delcena49
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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Thu Apr 11, 2013 6:26 pm

I found it. Im just going to take some pictures of mine and post them. Maybe you can tell me by looking at my pics if it is right or not. If I can't figure it out myself I'm going to have to hire a certified mechanic to do it for me.
ARE THERE ANY CERTIFIED MECHANICS OUT THERE WHO WILL HELP A GIRL FROM OROVILLE CALIFORNIA RUN THE VACUUM HOSES ON HER TRUCK? lol

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fastboatman29212
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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Thu Apr 11, 2013 6:49 pm

Delcena49,
I have a 1984 factory service manual. If we start with one hose at a time, we should be able to get things hooked up correctly, BUT IT WILL TAKE TIME. It can't be done by just examining a few quick pictures of the engine bay.

I can see some of the hoses in you photo. Are you using a cell phone for taking pics? Maybe you can post them in a larger format or use a weblink like Photobucket so we can a get really good look at what things look like.

First question. Does the truck actually run right now?

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delcena49
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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Thu Apr 11, 2013 7:29 pm

Yes my truck runs. I just turned it around to take more pictures. I would like for you to see them. I just up loaded them to photobucket and am getting ready to post them. I know it will take time but my concern is some of the connections. I will post the pictures of what I am talking about first. The manual doesn't show what Im talking about.

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delcena49
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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Thu Apr 11, 2013 7:31 pm

Image

The manual does not cover these parts. These are on the passenger side above the wheel well.

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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Thu Apr 11, 2013 7:33 pm

Image

Here is the canister in my truck. It is different than the one you show.

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delcena49
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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Thu Apr 11, 2013 7:38 pm

Image Image Image Image Image Image Image Here are some more pics.

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fastboatman29212
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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Fri Apr 12, 2013 3:16 am

Ok, I think we should first move this whole thread over to the regular thread area. We are in the carburetor thread section now. It should be in the general section.
The photosare good. I looked at each photo but I do not see any hoses that are not connected. You will need to use a pointer to indicate what hose you need to know about and show where it starts. Then I can tell you where it goes.

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delcena49
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Re: 720 Carburetor Tutorial with Pictures

Postby delcena49 » Fri Apr 12, 2013 7:15 am

Okay, how do I get to the regular thread area and how do I use a pointer?

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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Fri Apr 12, 2013 10:10 am

Delcena,
By using a pointer, I just mean you should point at exactly what you want us to see in the photos you post. Just use a stick or pencil or piece of stiff wire or a sticky dot to show which piece of vacuum tubing you are talking about when you take a photo. It's a lot easier than saying "the little black hose just above the silver thingy . . . . " LOL!

I started a new thread for solving your vacuum issue. Always use the new thread to post questions related to your vacuum lines so we can stay on topic. To find it, just click this link: vacuum-lines-for-delcena49-t573978.html

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Re: 720 Carburetor Tutorial with Pictures

Postby ryanrockwood » Fri Jun 21, 2013 3:52 pm

Hi there, I'm wondering what adjustments, if any, can be done on the carburetor to lower the hydrocarbon emissions so that it can pass the DEQ test here in Oregon. It barely failed the first time I took it in to try and renew the tags. I tried a week later and the levels were worse, so I put in new spark plugs- then the readings were much worse and was told that the fuel mixture maybe needed to be a little leaner. I've tried adjusting the mixture, the idle speed and even the timing but it still won't pass the hydrocarbons test. The exhaust system is only a couple of years old and the truck otherwise runs pretty well, as far as a 30 year old pick-up goes anyway. Any Thoughts?

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fastboatman29212
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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Sun Jun 23, 2013 7:21 am

Make sure you have the idle set at the correct rpms.
Check for any vacuum leaks.
If you have over 300,000 miles on the truck, you might need a new catalytic converter.
That's all I can think of.

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Re: 720 Carburetor Tutorial with Pictures

Postby Dondon20 » Mon Sep 23, 2013 2:17 pm

hello first off i wanna say awesome page for this truck .... i just bought a 1985 Nissan 720 2wd standard and been having trouble with it vibrating really bad when i get to between 40 mph and then it goes away then when i get to about 50 in 4th or 55 it starts up again its alot of vibration and i spent over 500 fixing the breaks calipers ball joints and tie rods ends and none of it fixed the problem but only slightly helped some steering and breaking now i have noticed some days it runes great untill i get it going about 45 50+ mph and it sounds like its not timed or something or its missing or something but then some days it sounds fine ... i took the blower off and looked at the carb iv noticed some leaking between the seals like it over flooded the carb and so there for i have trouble starting the truck when its flooded of course i have also tryed messing with the idle and it seems alright but it smells very rich bruning today i calulated how many mpg i get and its about 17 mpg with a full tank i hear its supposed to be 24-25 well i can go about 250 or so on a full tank if i can get it going its about 10-11g tank i think ... i need some help as i dont know what to do more to fix it i love this truck and would love to get it starting again .... any ideas im also low on cash and am trying to find the cheapest way to fix this .... also it wont stay running with its cold till it warms up after a half hour or warmed up and anyways back to the carb blower i took off it has a rod that hangs there and connects to some suction valve but as i see its like that valve isnt connected to anything anyways idk what to do please help

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fastboatman29212
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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Mon Sep 23, 2013 4:14 pm

Your list of problems is very long. I think the vibration at 45 and again at 55 may be due to old tires or tires that are not properly balanced. It could be as simple as that. Vibration that is at one certain speed and then goes away is not likely from the engine.

If the carb is leaking then you need to rebuild, or replace it. Rebuild is cheap but not everyone can do it.

Those are the 2 major things I can understand from your post.

huitronjonathan
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Re: 720 Carburetor Tutorial with Pictures

Postby huitronjonathan » Sun Oct 13, 2013 11:57 pm

So I recently bought a 86 720 and I am no where near familiar with carbureted motors. How do I take the carburetor off to rebuild it? And how can I tell whether I own a 2.0 or 2.4? Sorry for the dumb question at the end.

If anyone could help me I would really appreciate it.

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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Mon Oct 14, 2013 4:11 am

You should check out the DIY section. It will help you fix your truck and save a lot of questions.
Also, you should try and buy a Factory Service Manual for your year truck. A good investment.

How to rebuild a Hitachi carb. See this link z24-carb-rebuild-diy-1984-86-t537596.html

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Re: 720 Carburetor Tutorial with Pictures

Postby huitronjonathan » Thu Oct 17, 2013 1:14 pm

Okay thank you. I found out it's a Z24 2.4. Other question. Will the Ka SOHC valve cover fit the Z24? I need a place where I can find a store or site where I can actually find one. Preferably a performance one. Thanks a lot fastboatman29212.

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fastboatman29212
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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Thu Oct 17, 2013 3:37 pm

huitronjonathan wrote:Okay thank you. I found out it's a Z24 2.4. Other question. Will the Ka SOHC valve cover fit the Z24? I need a place where I can find a store or site where I can actually find one. Preferably a performance one. Thanks a lot fastboatman29212.
Can't answer your question about the valve cover. This thread is about carburetors. You might get an answer if you start a new thread and ask there.

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Re: 720 Carburetor Tutorial with Pictures

Postby huitronjonathan » Thu Oct 17, 2013 8:04 pm

So I decided to go with a dual cam instead. Just have to find if I can still use my own tranny from the Z24 for the dual cam

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Re: 720 Carburetor Tutorial with Pictures

Postby sectionecho » Wed Mar 26, 2014 4:16 pm

Hey fastboatman, you sure know your way around these trucks! Let me ask you something about this carb. For some reason whenever I move the fast idle arm up the throttle goes to normal idle speed, but as soon as I press the gas the fast idle arm clicks up a notch and the throttle goes to 3000rpm. It will stay that way until I physically push the white fast idle thing down, then it will idle normally, but as soon as I move the throttle it jumps to 3000 and stays.. Any help would be greatly appreciated.

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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Wed Mar 26, 2014 4:44 pm

sectionecho wrote:Hey fastboatman, you sure know your way around these trucks! Let me ask you something about this carb. For some reason whenever I move the fast idle arm up the throttle goes to normal idle speed, but as soon as I press the gas the fast idle arm clicks up a notch and the throttle goes to 3000rpm. It will stay that way until I physically push the white fast idle thing down, then it will idle normally, but as soon as I move the throttle it jumps to 3000 and stays.. Any help would be greatly appreciated.
Sounds like the return spring for the fast idle cam is stuck or broken. Or maybe it just needs some lubrication.
Look at the Z24 Hitachi Carb DIY Rebuild Thread I made so you can get an idea about how the Fast Idle Cam works.
z24-carb-rebuild-diy-1984-86-t537596.html

Here are a few pics. There is a tiny thin spring that causes the cam to move back to the "slow idle" position.

Image

Image

astro800
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Re: 720 Carburetor Tutorial with Pictures

Postby astro800 » Mon Jun 16, 2014 11:04 am

I have 84 4×4 carb is making clicking noise and it won't hold idle. I changed both relays not sure what's up with it. I just bought it for 2500 and it won't run. I need some help thanks

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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Mon Jun 16, 2014 11:16 am

Try posting in the general section as a new post. It will get a better response there. Pictures help. "Clicking" is not enough info to get started with.

Unless the carb has been really messed with by other folks, you need to track down any vacuum leaks. If the engie will start and run, but just won't idle, then maybe you can start by adding a bottle of carburetor cleaner to 1/4 tank of gas and run the tank almost dry by driving around. That should clean out most fuel pathways in the carb.

Check to see what level the fuel is at in the fuel bowl using the sight glass on the front of the carb.

Again, try posting this as a new post. You might get better help.

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Re: 720 Carburetor Tutorial with Pictures

Postby truckerjonesy » Sun Sep 07, 2014 7:13 pm

Afternoon all

well im having a few problems with my carb on my

1988 D21 Z20 2WD

while driving around,u come to a stop sign and the ute keeps a very fast idle (have to drop in 1st gear, slip the clutch and that kills the revs back to a normal idle) :wtf2:

all the butterflys on the top of carb return and all likages spring back after reving but the revs stay high :tisk:

only doing when warm
have check and reset float hight, idle speed, and mixture screw, and a can of CRC Carb Clean

any help would be great!!

anyone have a link to a tune up guide for the Z20?

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Re: 720 Carburetor Tutorial with Pictures

Postby AZhitman » Sun Sep 07, 2014 9:00 pm

Welcome aboard!

Sounds like a vacuum leak is the culprit...

While we didn't get the Z20 engine here in the US, you have a D21 Hardbody with an earlier engine (D21 in the US have the KA24 engine). I would have a look at the 720 manuals at www.datsunservicemanuals.com. The Z24 and Z20 are similar in terms of the tune-up process.

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Re: 720 Carburetor Tutorial with Pictures

Postby Horsinround_in_KY » Mon Oct 06, 2014 12:17 pm

Howdy,
:wavey:
I'm new here, and new to Nissan....So far in the past six months I've enjoyed both pretty well though, y'all have answered many questions without me having to post anything - great database of knowledge here!

I have a Z24 I just put a Weber 32/36 on as the stocker was pretty unhappy and I didn't want to bother rebuilding it. The truck runs SO much better and has multitudes more power but it's pretty sputtery on startup when it's cold out. A 'lope' I suppose it could be called and it smells very rich. I pulled the air cleaner and it looked like the choke was closed completely. I opened the choke butterfly a little with my finger and it speeds the idle up and runs smooth but closes back up and lopes afterward.
What voltage should be going through the electronic choke wire and when? Is it variable or just a constant 12 when the engine is running? The blue wire with red stripes is hooked to the choke currently as that was the one hooked up to the stock carb but the choke on that one was broken and I'm not sure if it was a wiring issue then too or what.

Just more explanation, maybe this is all working correctly - When the truck is off after running and being warm the choke valves are held open slightly. When I lightly push the throttle linkage they close fully and return to closed whenever the linkage rests back on the idle speed screw. If you open the throttle and keep the choke valve open slightly (maybe mimicking vacuum?) when you return the throttle to closed, the valves are held open slightly. I assume this is all correct....

I'm not sure if this is related but there are two relays in the cab against the inside of the passenger fender, one larger one higher up and a smaller one just below it. A couple days prior to my carb swap the lower relay started buzzing whenever the truck was running so I unhooked it - truck continued to run so I left it that way for the time being. I just checked and there's a blue/red stripe wire running to both of those. I've asked a couple mechanics but they weren't sure off-hand what they were for.

I have two vacuum hoses hooked up - The larger one that goes from the carb to the canister and the vacuum advance line to the distributor - all others plugged.


I'll get a couple pics of her later on and toss em up (separate thread of course)

Thanks in advance!

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Re: 720 Carburetor Tutorial with Pictures

Postby fastboatman29212 » Mon Oct 06, 2014 5:07 pm

Welcome to the forum. I think lots of folks who know about Weber carbs will be glad to help you.
This thread is intended for questions about factory Hitachi carbs.

Please re-post your thread in the general topic section and I'm sure you will get more responses.

ThomNickelson
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Re: 720 Carburetor Tutorial with Pictures

Postby ThomNickelson » Fri Oct 24, 2014 11:32 am

fastboatman29212,
I have a question about my carb. I recently purchased a rebuilt carb from "carbs6v4o" on ebay. It looks brand new and it starts right up. My problem is that (and I let it warm up for 5 minutes +/- a minute or 2) once it hits a certain temp (right in the middle of that cold to warm space) it wont stay running. I have to restart, give it gas and continue to let it warm up, once it's completely warmed up it runs great. I'm having a hard time adjusting, because does stay that temp long enough for me to fix

I should add that it's a 1985, 2 wheel 2.4

Any ideas?


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