Weber conversion go-to resource??

[Thomas Perkins]

No,I first bought the Redline Weber one, it had to be grinded and it didn't work,I still have it.They now have a new part number for the Weber one.They are the same diameter.I will show a picture of them side by side.Also other people had to grind it with them.Long ago I have a carb direct Weber,but it was not the real one,had a sticker on the side with serial number on it,it came with the black choke.The real redline Webers come with the white chokes.I will show pictures when I get home from work.I am going to put my new float on today.The other Weber came with a Idle cut off solenoid .Back when 720 World was on line with Corey.

[Thomas Perkins]

No Pine Cone.That will not work.Here is a picture of my choke off.You need to  grind that part a

little.You can use a hand file if you don't have a dremel tool.Here are both of my idle cut off solenoids.The Redline Weber is a little longer but the same diameter.The Redline is 9 years old.I could never get it to work.Wanna buy it lol.The solenoid that is gold and on the left side is the Redline one.I also have a brand new empi and a .60 big jet for a spare.If you were to take that piece off that choke goes into,then you would not get it back on.Time to Grind my friend.I am now taking the top part off to put the new float in.

Edited July 17, 2025 by Thomas Perkins

[Thomas Perkins]

Pine clone.I just took the top off.See how tight the solenoid is.I can tighten it snug with my fingers.

Edited July 17, 2025 by Thomas Perkins

[datzenmike]

17 hours ago, ggzilla said:

These engines didnt diesel until open chamber heads were used to reduce NOx. No amount of tuning will stop the problem

 

So starting in 1973 anti-diesel valve was added to all USA Datsuns.  Even Weber has an anti-diesel valve option for 32/36

 

To lessen the problem, lower the idle speed to 600rpm, but it will still runon sometimes

 

Couldn't be the anti knock tetra ethyl lead being removed from the gas in '72/'73?

[ggzilla]

Maybe. I searched for "causes of runon dieseling" and none of them mention closed chamber design or unleaded gas. All I know is tuning won't get rid of it on the Datsuns. No matter what you set the mixture to lean or rich or best or best lean, runon can still happen

On 7/17/2025 at 2:51 PM, datzenmike said:

 

Couldn't be the anti knock tetra ethyl lead being removed from the gas in '72/'73?

Unleaded gasoline was (by decree) July 1, 1974 widely available, in time for the 1975 model year and the first catalytic converters.

However, the 1973 Datsun owner's manual says: "Nissan Motors recommends the use of no-lead of low-lead (0 to 0.5 grams per gallon) to minimize emissions", so presumably you could buy no-lead fuel before July 1, 1974

 

Do you recall runon being common before the 1971 models? That's when closed chambers almost universally took over

 

[Thomas Perkins]

.The stock Nissan 720 carbs use a idle cut off solenoid.The first Weber like Carb I bought came with one.I even called them back then when I was having a problem.It was a Italian speaking guy.It was North American Carbs,Way before thr internet came out.Here is a picture of my old and new carb.The black choke is the non real Weber.It worked good.The Weber's with the white chokes are Genuine Redline Weber with part number engraved on the base.My non Weber had a sticker on it.I tried not using a solenoid on the new Weber and it would not stay idled.Another thing that may happen in time,the solenoid may come loose and make your Weber not idle. right.Use a o ring on the Empi type.I tried it without the o ring and it backed out.When tightening the solenoid,do it while engine  is running  to make sure you have it set right for it to idle perfect.What I do?The rpm need should be perfectly steady.No Weber gasket leaks too.I still use a Nissan 720 fuel pump.

[Thomas Perkins]

Here is what is says about the first Weber like Carb. I bought.Genuine" Weber carburetors are produced by Magneti Marelli in Spain, based on the original Italian designs. Weber North America, however, holds a license to use the Weber name and produces carburetors, often using different tooling and potentially from other sources like Solex, and may be considered "genuine" under their licensing agreement, but not necessarily the same as the original Italian/Spanish Webers. Markings: Genuine Weber carburetors will often have "Weber" cast into the body, along with "made in Spain". Clones may have stickers or lack these markings. 

[ggzilla]

5 minutes ago, Thomas Perkins said:

Weber North America, however, holds a license to use the Weber name and produces carburetors

Source? I find no information on a company named "Weber North America"

 

All the info I can find says RedlineWeber is the only distributor of Weber carburetors in USA

[Thomas Perkins]

They are no longer around.I bought that one long ago.They had a license to use Weber's name.As you see what I posted .Weber also owns Solex.They were made in Italy,now made in Spain.Got to watch for fake shiny Chinese one's.North American Weber Carburetors (or Weber Carbs Direct):

These are often marketed as "Weber" but are not the genuine European product. They may be manufactured by other companies, potentially in North America, and are not produced with the authorization of the trademark owner.Weber Carbs Directhave been doing research on "real" Webers and unless you buy in Europe you will only get a real Spanish-made weber through Redline dealers. Weber Carbs Direct has a license to reproduce Webers under the Weber name. From their website:

 

"Genuine WEBER carburetors are those manufactured by or with the permission of the owner of the WEBER Marks or an authorized licensee. Interco Products Corp. (dba Weber North America) maintains both a license agreement and a manufacturing agreement with Magneti Marelli Powertrain USA, LLC.

 

The WEBER trademark (U.S. Registration No. 1,685,066) and the W (design) (U.S. Registration No. 1,245,581) are owned by Magneti Marelli Powertrain U.S.A., LLC, a wholly-owned subsidiary of Magneti Marelli Powertrain S.p.A. (MM).

 

If you want to make their existence difficult, contact Magneti Marelli Powertrain directly and tell them what is going on. So far, it seems like James at Allautomotive on Ebay is quite reputable and knowledgeable, but I haven't placed my order yet. HE only sells true Redline products and at a very good price. Carbueretion.com seems good too. And of course Pierce. THIS PORTION HERE WAS POSTED ONLINE IN 2012,ABOUT THE TIME I BOUGHT MINE.I WILL LOOK UP MY RECIEPT AND POST IT.They are no longer around.

[Thomas Perkins]

ggzilla.I put the North American Weber on in 2004.It lasted 8 years,I sold it on 720 World back in 2012 for 125 dollars. when I bought the Redline Weber for 199 dollars.I took the idle cut off solenoid off it and put it on the Redline.I took off the primary jet and cover and put it on the North American.I did have the wiring hooked up wrong on the Weber.Corey from 720 World told me and had me hook it up right.I was just using the red wire to the choke and solenoid.It was dieseling.I hooked up the red to solenoid and blue to the choke.I also have a receipt when I took to the Nissan Dealer here for that problem.They did not know it was hooked up wrong.It says on invoice that I stated I put a Weber on it and it was dieseling and they wrote on it that they could not do anything with it cause it had a Weber on it.That invoice said June 2005.I also took it to them when it had the original carb on it and they said it was junk and told me to get a Weber.So I did.No internet back then.So the North American was a good carb.I should of kept it.I know more now than back then.learned a lot on my Nissan thru the internet.Mike has taught me a lot.Thanks Mike and ggxilla.You can't learn anything till you have a problem.

Edited July 19, 2025 by Thomas Perkins

[Thomas Perkins]

Back in the Day before I got the Weber.I spent a boat load of money trying to get the stock carb right.I replaced every valve connected to it,that was when Nissan had everything in stock.I have all the receipts.I paid 3 different carb shops 200 each to rebuild it.Got it back the same way as I first took it to them.Last resort was the Nissan Dealer.They told me it was a bad design carb,and said it was junk.Even quoted a price of 900 to do it and said that they could not get the bottom part taken apart and said they would not guarantee it.Easier to change spark plugs without that big air breather.I still have a brand new fram air filter in the box.I bought my 85 FSM from them back then for 75 bucks still have receipt.No more carb shops around anymore.

Edited July 19, 2025 by Thomas Perkins

[ggzilla]

thanks. I find the the old website Weber Carbs Direct The website stopped in 2017

* Weber Carbs Direct was a retail outlet for WEBER NORTH AMERICA, a division of INTERCO CORP.

INTERCO CORP. seems to still be in business, but it appears(?) no longer makes Weber-branded parts

 

Good to hear that their carburetor were good

6 hours ago, Thomas Perkins said:

the North American was a good carb.I should of kept it.

 

[PineClone]

I have these ports capped, but they keep coming off. I'd like to remove it and permanently plug the hole like i have with some of the others, but haven't had any luck getting it loose. I've put some moderate pressure on it with a wrench and the nut wants to strip. I have been hesitant to get aggressive with it for fear of breaking something. Any pointers?

 

Thanks in advance.

 

 

[datzenmike]

That's a Thermal Vacuum Valve TVV. Just leave it. It's threaded into the cooling system. If you just have to break something, try when the engine is hot. 

[TinKanTosser]

3 hours ago, PineClone said:

I have these ports capped, but they keep coming off. I'd like to remove it and permanently plug the hole like i have with some of the others, but haven't had any luck getting it loose. I've put some moderate pressure on it with a wrench and the nut wants to strip. I have been hesitant to get aggressive with it for fear of breaking something. Any pointers?

 

Thanks in advance.

 

 

+1 on just leaving it, it can't give you a vacuum leak without any vacuum source hooked to it right? If you really want caps on it to protect it or for looks you could use some of those crimp-type hose clamps, they don't take up much space or look awkward.

[PineClone]

Okay I'll leave it in place...that's the easiest solution and is low risk. However, I can always tell when one of those caps pops off because it idles rough.....so the caps are doing something.

Edited March 11 by PineClone
make better

[Thomas Perkins]

I still have 2 connected to my vacuum lines.Top one is not capped off.That one goes to the air filter on stock carb.I did use it on my Weber long ago.Did not notice any difference?Been that way for over 10 years.Leave it un capped.

 

 

[datzenmike]

5 hours ago, PineClone said:

Okay I'll leave it in place...that's the easiest solution and is low risk. However, I can always tell when one of those caps pops off because it idles rough.....so the caps are doing something.

 

No. If nothing is connected to the TVV it is impossible to affect the idle. The bottom of the TVV is heated by the cooling system.

 

The top hose on the TVV goes to the air filter so only filtered air can be sucked into the TVV.

The other two fittings go to the EGR and the vacuum advance/purge signal for the charcoal canister.

When engine is cold the bottom two lines connect to the top and air enters and the vacuum signal is destroyed. As the engine warms up the two lines seal and a vacuum signal is sent tot the EGR and the vacuum advance. Thus on a cold engine there is no vacuum advance, no purge of the charcoal canister and no EGR.

Both EGR and vacuum advance are ported vacuum source from the carburetor base. They are not connected to the intake vacuum. Instead the ports are above the throttle plate so when idling they have no vacuum signal. As the throttle is opened, the throttle plate rises above the two ports and some vacuum is felt and send down the hoses to the TVV. Obviously at heavy and full throttle the intake vacuum is close to zero and there is no need for vacuum advance of EGR.  

[NC85ST]

If one of the caps pop off of the fitting just to the left and behind the fitting circled, yes it will run rough. The one circled has no affect, you can pull all the caps off.

[Thomas Perkins]

I just took this picture of mine. Been like this for 10 years.That is how old my Weber is.Still use my vacuum lines.

[datzenmike]

Yup, best to keep all 'emissions controls' functional. 

[Austin]

On 4/28/2025 at 6:23 PM, Thomas Perkins said:

If you can find this K646 part number in stock, it has the correct throttle cable bracket. The universal kits have a bracket that moves the cable and changes too many things.

[Thomas Perkins]

Redline Weber does not sell a throttle kit for 83-85 Nissan 720.Only comes with the Weber with kit.The universal is crap.Also Weber does not  come with a throttle return spring.Also take your top part off and check and see if your float is set at 35mm.New floats you buy,tabs have to be bent and set at 35 mm.I bought a new Redline Weber float not long ago and had to set it.Same as the brass Floats.Someone I know bought the brass one and had to bend tab to get it set.Brass is not set at 35 mm.It is set at 41mm.Pegasus sells them and the springs.You may need to set your choke  and fast idle speed.Mine is set at 1700 rpm's.Works perfect.Always buy White Redline Weber replacement choke.Stay away from the black one's.A float should weigh 11 grams.If it weighs more then it is not set right.

 

Edited March 14 by Thomas Perkins

[giantcone]

My 1985 2WD 720 King Cab is close to 210,000 mi now.  I was planning on rebuilding my original Hitachi carb with a Walker rebuild kit I bought way back in 2013, but after reading this thread, I'm considering swapping to a Weber 32/36.  I've never really had much trouble with my truck starting up and running.  It has been rather weak going up hills though; I can't remember if that has always been the case.  

 

Seems that people here buy their Weber carburetors from Ebay mostly.  I was thinking of buying mine directly from Redline.  I found that I communicated with a tech at Redline back in 2014, but I didn't follow up on some information the tech wanted.  In my initial enquiry to Redline, I stated that I had interpreted some information that I read on another Ratsun thread that an ECU controlled Hitachi carburetor implies that a Weber carburetor upgrade isn't possible (I can't remember from which thread I got that idea from).  This was the response from one of their techs:

 

Quote

Please confirm a possible picture of your current throttle system please
take a picture of your engine with the air filter removed for viewing of
the carburetor or throttle system

also please confirm a small sketch showing the bolt pattern of the
throttle or carburetor at the intake manifold flange

a sketch with general diminsions will work for confirming our options

While the kit number may differ we have started to get requests for
early electronic throttle and injection system replacements and we have
done a few the picture and or sketch will help confirm if we have an
adapter for your application

If infact it is a low presure electronic throttle we can do this with
out fuel pump

if it is infact a low presure injection system we would offer both the
carburetor conversion with adapter and suggest a fuel pump and regulator
system upgrade to improve the over all function of your vehicle

I personaly would suggest the 38 38 dgas carburetor

:

:

Bud Pauge

 

Given what Mike stated about the 38/38 being too big, I find it odd that the Redline tech would suggest installing that one (maybe to get a bigger sale?). 

[datzenmike]

I would rebuild the stock Hitachi as it's the most perfect carburetor for your truck. Age and neglect has left it out of adjustment and in need of internal cleaning. That's usually what's wrong with an old carburetor. You have the kit just add some time to get it back in order. You might be surprised how well it works. You can always swap the 32/36 later if you want.

 

 

The 38/38 will work, it's just harder to live with. From a performance standpoint it has a bit more go but just how often do you run full throttle? Now if they made the 38/38 as a progressive secondary or better yet, a vacuum secondary it would be closer to perfect.

 

The ECC (electronically controlled carburetor) can be removed and a 32/36 substituted without much bother but if in California or where there are emissions testing it won't pass a visual let alone an actual tail pipe emissions testing.