Glad to hear another there's another one on the road.
I'm just curious if Weber Tech is starting to become aware of this set up. Did they give any indication? I'm hoping they will just start making a kit for the z24i.

I think on their site it says not for fuel injected models. Frankie I have a few questions. Took the truck out for a few trips to test my mpg and its not looking good. I took both trips with 5.5 gal. On the first run it was mainly 60-65 mph pretty flat ground and I got 20mpg. Second was a lot of inclines and declines returning home and got 12mpg. Any ideas. I did find the throttle sticking and truck running rich. Not burning eyes but it sprayed my garage wall with black soot. Any tips for me. I am actually loving to drive this truck again.

Well if it is leaving a black spot then it is running very rich, which completely explains the mileage problem.
First Suspect: the electric choke (and I'd bet money on it). If you look back on this thread, I explain how to adjust or disable it (my preference, especially in warm weather). Remember "electric chokes were a government conspiracy to waste gas.", according to some old man who restores air-cooled VW's. And they do that very well.

Warm the truck up completely (let it run for about five minutes), then turn it off and take the air filter off of the carb (quickly). The "butterfly" that you see at the top of the carb should be opened completely. If it is not, then adjust it until it is, then play with the throttle a little to make sure it stays put.

ALWAYS MAKE CARB ADJUSTMENTS WHEN ENGINE IS FULLY WARMED UP.

Second, and not very critical for mileage but will give a more precise idle: Add a return spring to the throttle, easy to do. Can be done in a number of different ways.

Your bet was rite. I discoverd that the butterfly for the electric choke was almost closed. I took some wire and held it open. It seems to have made some difference. i have to look back and see how to adjust it or disable it. I did have the idle issue. I added a return spring to the throttle but it still hangs a little rite at closed position. Where and how did u place your return spring. If you would send a picture I would appreciate it. Should I mess with the mixture screws.

Half way down page 1 there is a procedure for adjusting the choke. It's easy. Get rid of that wire, the linkages on the carb are fragile you don't want to damage them. I'm not saying you did damage anything, it just made the hair on the back of my neck go up a little.

Don't go the adjustment screws yet. When adjusting a carb, follow this order:
1. Verify that you have no vacuum leaks and that your ignition, fuel system and carb are working properly. Engine must be at full operating temperature. You cannot proceed to adjustment without these crucial parameters.
2. Adjust choke.
3. Set idle to rpm recommended by the manufacturer of the engine, and follow the recommended procedure from the manufacturer of the carb to achieve it (so car will stay running). Don't just turn the screw. I know it's right there where you can see it, but that is rarely the correct way to set the idle.
4. Smell the exhaust. DO NOT INHALE IT (gotta put that there for stupid people). Just hold your hand or a piece of cardboard in front of it and then smell that. Do you smell unburned gas (rich)? Does it make your nose and eyes burn (lean)?
5. Most carbs are tuned at the factory to give near-perfect mixture ratios if all these other things are in order. The only way that you or I will be able to get that close is with an Exhaust Gas Analyzer, which I don't have and am guessing you don't either. There is another option of installing an O2 sensor and a "mixture gauge". I chose not to, mostly because of cost. As I've said before this whole project started because I needed a cheap dependable beater that gets good gas mileage. This truck is not my baby, more like my lab rat.
So if you choose to mess with the adjustment screws, which you undoubtedly will at some point (I did), then follow the procedure from Weber very carefully and pay attention to how the engine is running. There are three distinct effects to watch for when driving.
The first one is obvious when it happens, that is the flat spot. You put your foot down hard and the engine just stops completely for a second, then lunges forward. That indicates a lean condition. The second and third are not so obvious and are harder to read; that would be lean surging, and rich surging. Surging is exactly what it sounds like. You're accelerating, but not smoothly. Lean surging is more common and there is a delay from the time you open the throttle to when the surging begins. Rich surging happens instantaneously when you hit the gas.
6. You've done everything and it's still got one of the three symptoms or the exhaust isn't smelling right and you're ABSOLUTELY SURE that step 1 is 100%, then it's time to start re-jetting. Jets are easily replaceable. Kits are cheap. Major corrections to fuel mixture tuning are made by changing out jets for larger or smaller ones.

Frankie let me first say i appreciate all the info and your help. I love this truck now. I have been putting down the miles and having fun. I did take your advice and remove the wire from the choke. I simply disabled the electric choke for now. I have yet to mess with the mixture screws kinda hesitant. As far as being lean or rich here are my results. From a dead stop I can rev and dump the clutch. Not flat spot just wheel spinning even snatch second all through the gears just acceleration. Pulling on a grade steady smooth throttle response. No surging or jerking. Exhaust has a smell not terrible nor does it burn your nose or eyes. I may just have to live with it the way it is. It's running so good I hate to mess it up. Gas mileage is a lot better than running it with the choke closed. Any more suggestions would be appreciated. Also can you post a pic of where you connected your return spring

That makes me smile.

It sounds like you're in business. I'll post that picture when I get a chance.

On my other rig (not a nissan) I put a fuel pressure regulator on it and set it to 1.5 to 2.0 psi and that weber seemed to get better mpgs. I think the higher pressures were pushing extra fuel through the needle and seat.

Just another thing to think about but sounds like you have it nailed.

Longtooth. I was assuming the same thing but the instructions say the carb needs 3.5psi to run. I have been testing at different pressures. I can go as low as 2.5 but in about 3rd gear it get surges like its starving for fuel. It would be nice to get a few more mpg.

I grabbed some 16" Alloy wheels off of a Honda Passport. I can't recall the tire size but it made all of the gears a little taller. Keeps me on the idle circuit a little longer. I have heard mixed opinions about camper tops and aerodynamics, but I believe that on the highway they help. Eventually, you will adjust the mixture screw, I can feel it, with the intention of making it run as lean as possible. That was why I did it.$$$

Just basic tune-up and valve adjustment (oh yeah these trucks have adjustable valves) will also help a lot.

And this has me thinking about making another one...
http://washingtondc.craigslist.org/nva/ ... 08586.html

dongatta wrote:Longtooth. I was assuming the same thing but the instructions say the carb needs 3.5psi to run. I have been testing at different pressures. I can go as low as 2.5 but in about 3rd gear it get surges like its starving for fuel. It would be nice to get a few more mpg.

If your nissan wants it then I would let it have it Like I said before I have one on another car line with a very small engine (1.3)

Well messed with the mixture screws today and only got to turn them in one full time before it started running rough. Backed it back to the original spot and running smooth. Exhaust still rich. May have to get a jet kit

You're gonna have to play with it more than that!
Tuning by ear and nose is an art and even seasoned pros will often take a couple tries to get it where they want it. I'm not saying you don't need jets, maybe you do, but if you got the carb from Weber already set up for a Z24 then you probably don't.

Make small adjustments, 1/8 to 1/4 of a turn and don't assume that you're adjusting fuel either. Some adjustment screws control air so turning the screw out makes it leaner. Check the literature that came with your carb. Drive a little when you think you've got it and look for the 3 symptoms, then make further small adjustments.

whats up frankie!! thanx for posting this.. i have a 86 1/2 hardbody with this stupid TBI! i bought me a 32/36 weber, adapter plate, little filter for valve cover, carburated intake mani and vaccum advance distributor.. i was gonna do this swap and eliminate all emissions, like you say SPARK, FUEL, COMPRESSION...i was only baffled by fuel system and you made it CLEAR..im in the process of buying my fuel pump and FPR.. i bought the intake mani and dist from some wrecking yard only for them to sell me the shaft that runs the oil pump/dist, after i read your post i will be selling the dist... i have a few questions;
1) the posting you put about removing the air flow sensor and TPS(removing the wire to the air flow sensor only).. that was just a test? correct? so when you installed the weber carb, these sensors are not hooked up and wiring to them are secured out of the way?(not cut?)
2) the return line as you have pictured is the line that is currently connected to the FPR on the TBI ?
3) what have you done with the fuel evaporation canister? removed?
4) you also stated that when you posted the font was different, could you post pics of the other halves of the pictures?
nice job with the mounting of the stock air filter

THANX AGAIN, much appreciated

whats up frankie!! thanx for posting this.. i have a 86 1/2 hardbody with this stupid TBI! i bought me a 32/36 weber, adapter plate, little filter for valve cover, carburated intake mani and vaccum advance distributor.. i was gonna do this swap and eliminate all emissions, like you say SPARK, FUEL, COMPRESSION...i was only baffled by fuel system and you made it CLEAR..im in the process of buying my fuel pump and FPR.. i bought the intake mani and dist from some wrecking yard only for them to sell me the shaft that runs the oil pump/dist, after i read your post i will be selling the dist... i have a few questions;
1) the posting you put about removing the air flow sensor and TPS(removing the wire to the air flow sensor only).. that was just a test? correct? so when you installed the weber carb, these sensors are not hooked up and wiring to them are secured out of the way?(not cut?)
2) the return line as you have pictured is the line that is currently connected to the FPR on the TBI ?
3) what have you done with the fuel evaporation canister? removed?
4) you also stated that when you posted the font was different, could you post pics of the other halves of the pictures?
nice job with the mounting of the stock air filter

THANX AGAIN, much appreciated

Hey giggles808 if you are parting with the vacuum advance distributor I may be interested. If you look back in earlier posts I have completed the swap as well. Disconnect all tbi wires and place the securely out of the way. Do not cut. I have the same weber carb. Truck runs great still a little rich may have to live with it. Only thing I can't get my electric choke set up just right. Let me know on the dizzy

@ dongatta.. thanks for the reply.. what about the fuel return line? is this the line thats currently connected to the FPR on the TBI? and i know that frankie stated over and over, i read this thread over and over, that he used the stock fuel pump? is this meaning the 22 psi pump? and because the design he shows, it relieves most of the pressure? will be doing the swap in a few days and i want all my kinks ironed out... also i live in Hawaii, i dont know if i was looking in the wrong place, but all wrecking yards here, didnt have parts for this truck, atleast not at the time i was looking for them.. i looked on craigslist in Hawaii and there was only complete motors for 400, 450 or more, some of the trucks from craigslist that i did check out had the same TBI system.. i like how frankie has drilled his existing manifold, but im going with the bolt-on version i came across this sight from craigslist thats a nissan/infinity wrecking yard, located out of washington, feltonautoparts.com or 1-800-713-3999
got my intake mani for 65$ and the dizzy for 45$ and they told me that i would need to get the shaft that runs the oil pump/dizzy.. got the shaft for 15$.. i spoke with this rep. named Greg, who sent me pictures of products before i purchased. if you live in Hawaii..ill def sell to you. if not give them a call. i got all parts with shipping to Hawaii for 185$. sent FEDEX ground so i should be recieving my parts today.

let me know about those other questions, would be greatly appreciated..

THANX AGAIN FOR THE REPLY

@ giggles808. I live in va. Yes u have to put a tee after the fpr then connect the return line. Insert a short piece of 1/4" vacuum hose in the return line to give some restriction or the fuel line will push the same amount of pressure back into the tank. I also am using stock fuel pump. 22 psi. I am using the tbi dizzy. I would like the vacuum advance dizzy if u don't plan on using it. In va there are hills and steep grades that while empty on base timing I do fine. The vacuum advance would give me the extra boost I need when pulling my trailer or loaded. Try the regular dizzy first and u will see a very noticeable difference. Let me know on the dizzy

http://i58.photobucket.com/albums/g241/ ... system.jpg

http://i58.photobucket.com/albums/g241/ ... mdonts.jpg

http://i58.photobucket.com/albums/g241/ ... NY0483.jpg

UPDATE TO MY SWAP; I have completed this swap in about 6 hrs, i used the intake manifold from a DATSUN 720, so no modifying or drilling, i plugged all vaccum lines, removed EGR valve and fabricated plate to bolt up and plug hole..
I installed new gasket w/ the intake manifold, bolted on the adapter plate using loc-tite, installed 32/36 weber (DFAV model), i fabricated a throttle cable bracket, i did the fuel system exactly how Frankie says/pictures; stock fuel pump to stock fuel filter to TEE, 1 outlet of TEE going to stock return line with 1" of smaller hose inserted to restrict fuel flow and the other outlet going to FPR (i used the mr. gasket 1 that Frankie has used) outlet of FPR going to carb (i havent installed a fuel pressure gauge).. after installation of all components, its time to start? (im skeptical because the carb was bought used, from a garage sales) the truck started on the first crank , the motor sounded like a totally different motor, it purrrrred....
Only 1 day has gone by and truck needs a little fine tuning, but theres noticeable difference in HP/TORQUE gain, i have yet to see the MPG's... even with the EFI distributor the advance/power is good
I havent even used the secondary on the weber, dont get me wrong, i have tested full throttle on the initial test drives, but in my everyday commute the primary has enough power to get me to where i need to go...
NOTE; prior to this swap, i removed the secondary air system, more emissions , located next to the 2 coils, this has 2 tubes going to exhaust, 1 to the cat and 1 to the exhaust manifold, these tubes have been cut off and welded shut as well as the tube coming from the EGR valve..
@Frankie THANX for this thread
@Dongatta THANX for the info
1 more z24i converted to weber on the road

word. I was just reading about a growing trend involving American V8's. Due to popular demand, there are aftermarket manifolds made for new engines that will accommodate carburetors... mostly desirable for their simplicity and cost effectiveness.

So I wonder how many of these are on the road now.

I've put over 40k on mine since the conversion now. That's what commuting in VA means.

giggles808 wrote: 1) the posting you put about removing the air flow sensor and TPS(removing the wire to the air flow sensor only).. that was just a test? correct? so when you installed the weber carb, these sensors are not hooked up and wiring to them are secured out of the way?(not cut?)
2) the return line as you have pictured is the line that is currently connected to the FPR on the TBI ?
3) what have you done with the fuel evaporation canister? removed?
4) you also stated that when you posted the font was different, could you post pics of the other halves of the pictures?
nice job with the mounting of the stock air filter

THANX AGAIN, much appreciated

I realize that I'm a little late answering these questions, but maybe someone else will find it useful.

1. I cut mine, except for the one wire that I found that gives battery voltage when the ignition is on. I ran that to the choke. I'll check what color it is and post later. I have mentioned that I do not use the electric choke, even in the winter (-5 degrees), but I could easily hook it up again if I got some strange urge. I cut everything that ran to the TBI just because I hated it. You don't have to cut the harnesses. In fact, it would be pretty easy to reverse this process and bring it back to TBI if you didn't cut the harnesses.
2. Yes that is the stock return line that I'm using.
3. I left the evap canister right where it is. If you want to hook it up, there is already a vacuum port on the carb designated for the evap canister. I recommend leaving it there and maybe even using it. Not using it won't noticeably effect the way that the truck runs. But, your gas tank has to breath, and if you don't hook it up then you must leave the vacuum lines on the canister open to vent the gas tank to atmosphere. Agents of the EPA have shot people for less.
4. I will repost all of the pictures.

Hello, I'm new to this site but I just converted my 86.5 4x4 hardbody to a weber carb. and so far I am not impressed at all. I was wondering if anyone has any ideas. I did everything just the way Frankie expained to do it and it does not have much power and still gets horrible gas mileage the best I can get it to is 17mpg. I have tried adjusting the valves , changing the timing and re jetted it twice. The motor is in good shape I just rebuilt if less than 7k ago the compression is still good.

Reh4960, 17mpg is realistic for a 4wd. They are geared lower than 2wd's in both the rear end and the transmission itself, are a few hundred pounds heavier, have bigger tires, and sit up higher so are less aerodynamic. They were never meant to be fuel misers, even though they are still slow.

I have observed that generally the 4x4 version of most trucks get about half what the 2wd version gets. That means 17mpg is almost exactly, maybe even a little better than what you should expect.

So about the power issue, What carb are you using and is the truck showing any other driveability issues?

Thank you Frankie for the info on this forum. I followed your procedures outlined in this post and performed this conversion on my 1987 D21 2wd. I fabbed an adapter plate from some 1/4" Aluminum plate, and drilled and tapped it for the carb studs. It fired up on the very first try! I did find that the return spring supplied w/ the kit is a little bit weak and does not fully close the throttle every time I lift my foot, but that so far is the only glitch so far and should be easy enough to fix... I am very pleased with the hp and torque gains; this truck is a little scary now, it really pulls hard-especially in 3rd gear floored. I purchased this truck new in 1987. It became "exempt" this past year for emissions inspections in Georgia as it is now 25 years old-so I can do with it as I please now.
Right now I'm running the Weber along with the original stock air cleaner (modded to fit the Weber) with a K&N filter, tube header feeding a straight 2" exhaust, a compact Catalytic Convertor, and a Cherry Bomb glasspack. It runs like a scalded dog!

It runs better now and has more hp than it did when I bought it brand new. You have helped unleash the beast living in these little Z24's, and for that I thank you.

I'm so glad that others have had the same success that I have had with this setup. I have to post an update.
I have put about 55,000 miles on the truck since the conversion. I drove it to Florida at least four times, the Outer Banks twice. I drove it to Key West and back once. It has never broken down on me once or ever left me stranded. It has been a great truck, and I will probably deeply regret selling it.
It has found a new home with one of the service writers at my shop. He immediately rebuilt the manual trans, changed every fluid before he even drove it.

It will have a good life.

As for this thread I see no reason to neglect it any more than I already have (sorry). So if there are questions, keep them coming. Also I am beginning a new project. Codename: Howagen
Mission: To put obd0 sequential Honda fuel management on an '89 Volkswagen with mostly stock 8v engine.

Funny thing was, I knew the idea would probably not be well received on the Honda or VW forums, so I put the discussion on IATN until it is completed. I feel like I'm on to something here. I'll go more public with it when I get it working right.

I'm the new owner of Frankie's monster aka Marvin.
Long story short, I've been wanting an old beater...Haven't had one since high school. When Frankie described this carb conversion I was really interested in this truck. I was very impressed with his knowledge and the way he pulled it off. The truck is really fun to drive. Bare bones as far as options. No power steering, windows cup holders, tachometer, not even a little tab for the rear view mirror. In spite of all that, I do enjoy driving this truck. It's way more fun than my 07 civic.

Like Frankie mentioned i did have the transmission rebuilt. I intended on doing it myself but after disassembling the case from the main assembly, I quickly realized I was in over my head I did the clutch, flywheel and throwout bearing at the same time. I intended on doing the pilot bearing and the rear main seal. Turned out to be a PITA and neither one were bad so i left them in there. Changed the diff fluid with a quarter quart of lucas and the rest 75w90 straight valvoline.

At the same time Frank mentioned the rear brakes were acting up. One wheel cylinder wasn't retracting properly. Frank peeled back one of the boots and rusty brake fluid came out. I replaced the wheel cylinders, resurfaced the rear drums (against my better judgement), and flushed the old brake fluid. So if i did a coolant flush and oil change, I will have changed all the fluids.

Note: The guy at the transmission shop did advise me to either use 75w90 or straight 50w motor oil. I took his advice and filled up the tranny, through the shifter, with half a quart of lucas and 2 quarts of 50w (Valvoline Conventional Racing Oil. This did over fill it some but it's been working well. I'll see how it works when it's cold and adjust fire from there

The truck does have little quirks. ie: sometimes when it's hot it will kinder sputter when you turn it off, aka "dieseling". Tuning issue with the carb, NBD.
I have read similar issues like when i brake hard the truck pulls to the left. Again, NBD but i will be looking into replacing some bushings in the future.
The speedometer needle is broken so it's a little tough to see how fast I'm going. Easy fix. Plug in my gps and it tells me how fast I'm going, too easy
There is a flat spot when taking off while the engine is cold. I work around it now easily with the clutch.

Possible Future Mods:
Exhaust. If it rusts out (which could be any time)
Urethane Bushings
Rear sway bar kit.
Rear helper spring/shocks
Shocks front and rear (KYB Monotube)
Not likely but Frank mentioned a propane conversion
Rear locking axle (going to be hard to find)
Aftermarket Tachometer
Front bucket seats
Stereo/interior etc, etc, etc
A/C? possible but ghetto as hell, lol

hello did the conversion very happy with it but need to know how or where to hook up throttle return spring so it doesn't interfere with throttle opening or closing any pics anybody has would be much appreciated thanx

Frankie. new to this site. have been studying your posts for a few days now. i actually have a brand new Z24 engine in a 1984 720. but the truck was tottaled right after engine install so it has been sitting in my field for about twelve years pulled it out threw on some jumper cables fired right up. So i bought a 1986.5 hardbody with the z24i then right after i bought it started having problems with the mass airflow sensor. so i did a swap took the 84 intake and original carb off and installed it on the z24i block. i get what u say about the tee thing with the ruturn line and all. however i do want to know what about the return line that comes off the carb. where do you send that to or do you plug it or something.