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TOPIC: Nissan 1400 LDV Change from standard carb to 36 weber DCD

Nissan 1400 LDV Change from standard carb to 36 weber DCD 04 Apr 2016 10:47 #1

  • Martin Swart
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Hi Everyone.

This 1400cc LDV nissan comes with a Carb that has a steel area where the throttle plate is.

So in order to do the Groove I am thinking of changing the carb to a Weber 36 DCD

Please Advise.

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 04 Apr 2016 11:37 #2

  • Martin Swart
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A few Photos






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Nissan 1400 LDV Change from standard carb to 36 weber DCD 04 Apr 2016 20:12 #3

  • Tracy Gallaway
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That's a cool little mini-pickup! Must be about 30 or more years old, but looks in great shape...

OK, yes I dealt with an iron carb. throttle body 4 yrs ago, my Subie had a stock carb w/ an iron throttle base. I won't bore you with the whole story, I did Groove that carb, but could only give it a partial groove due to it's configuration. Then 3 yrs ago I did a Weber 32/36 DGEV carb swap, using an aluminum adapter plate. I Grooved the Weber, and the Subie loves it. I was shocked at the power increase when it was first installed w/ box-stock jets, felt like more than doubled power. I got a jet kit and re-jetted the Weber, a process that I spent a few weeks on. This carb setup is the one that got the 72 MPG Orange Test results 2 summers ago.

Now, I don't know about the DCD Weber, it seems like a lot of carb CFM size for a 1.4L engine. But if you can get jets and jetting info for this carb, as well as all else to deal with in a carb swap, it will make that little truck fly! That is an odd looking design, the top looks like another throttle body!

When Grooving the Subie's original carb, I was surprised at how well the bit cut the iron. But I can't advise Grooving in Iron, Iron is harder than Aluminum. Too easy to wear that Gadgetman bit, IMHO. Ron chaffed me about my concern for the bit later on, But I was paranoid anyhow! :oops:

If this is your truck, then it can be a nice project, might need some time to pull off right. If it's for someone else, well this is not a Quickie job IMHO. Partly depends on your familiarity with Weber swaps, and carb swaps in general, plus availability of needed selection of jets. I have read on Webers, BTW, it's fine to change Primary and Secondary jets, Idle jets and the Air Correction jets in the Emulsion tubes, but leave the Emulsion tubes alone, unless/until you are Expert with Webers. I would jet that Weber conservatively, 36/36 size barrels is a big one for that little Nissan engine.

As to Grooving the Weber, just look at it to see how the Groove location in Primary barrel looks like, I'd get a look at that area just like any TB, before buying it, if you don't have it yet.

Now, I gotta say,, if this truck has Electronic Ignition already, and a distributor, as in conventional. And if it's yours...it looks like it is an uncluttered engine bay. There should be room to add a Plasma Jet Ignition mod to it, Ive done posts w/ pics about it. The most Bad Ass spark you will ever see, guaranteed! The spark this kind if ignition makes, is reputed to GROW under load...I Can go on and on about it, but I'll save that... :lol: IT's pretty involved, and you need to already be pretty familiar with Ignition basics. There is an info download package about it from Aaron Murakami, it was $37.00 3 yrs ago, and it's where you start with it. I have sources for all the parts needed, it requires very specific things w/ no shortcuts...

Tracy G
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Nissan 1400 LDV Change from standard carb to 36 weber DCD 04 Apr 2016 22:45 #4

  • Martin Swart
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Tracy.

Thank you for the great info. I can get a 28/36 and 32/36 weber carb as well. From what you are saying the 28/36 or 32/36 might be a better buy.

I am very familiar with Aarons plasma spark ignition. I also bought the ebook but have not yet built one. It works out quite expensive if you look at the rand dollar exchange rate which hovers around R 15 to the Dollar. That is why I don't think it is an option at this stage.

It is not my vehicle but its my brother in laws Father who has 2 cars and he drives around 2 times a week to buy bread...... I am sure I might be able to keep the vehicle for at least 2 weeks.

Yes that Carb is in 2 stages. Stage 1 is steel and stage 2 is the aluminium upper part.

Are you saying I can cut the steal withe bits and that Ron is fine with that?

Thanks again for the response.

Martin

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 05 Apr 2016 01:02 #5

  • Tracy Gallaway
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Ok. Do some close research on the available Webers. The 28/36 seems most ideal to me. you might research sites like Redline Webers, they are a main importer of Weber carbs to the US. Need to think about choke type, linkage stuff, manifold adaptor, ect. There is likely an importer of Webers for SA, I'd look for that. Then there is jetting- the company in Oregon I bought from had jetting kits and recommendations on that too. The type I used is the 32/36 DGEV, with electric choke, it has been a great carb. The Subie's engine is 1.8L One other thing is a fuel pressure regulator, I used a cheaper one but it got a leak and I deleted it. Weber's are real sensitive to fuel pressure, I think it's recommended to limit to 2-3 lbs. pressure, there are Weber pressure regulators available.

Ron said the bits will cut iron, and they will, but at risk of shortened life. I sought out a tool shop where the single proprietor ( who had a huge shop w/ maybe 50 different work stations!) looked at my Gadgetman bit. With over 40 years experience, he had never seen anything like it--and remaking/fashioning bits was his specialty. I brought a high speed steel ball cutter I bought elsewhere to him, and he cut and modified it into a "hack" of the Real Thing for me. A very rough copy it was, I used it to do first stage Grooving on my stock Iron carb. throttle body for the Subie. Then finished up with the actual bit, all to preserve my real bit. IT worked, there was perceived improvement to the Subie. but nowhere as good as the Grooved DGEV 32/36 Weber. And the Weber has jets to tune it, the stock one not so. A big consideration w/ carbs, IMHO. The iron throttle body is common in Japanese carbs. I don't recommend using the Gadgetman bit in Iron, though it will do the job. Remember, Ron had access to new bits anytime! If you remove and examine the Primary bore of that stock carb, I bet you will find something that would compromise your Groove job on it. A funky vacuum port, or a big screw recessed into a cavity next to the bore, that limits your Groove's width. And how to re-jet it...?

So you have Aaron's Ignition Secrets download? Wow, you are a Gadgetman in more ways than one! ;) IF the Nissan's ignition is a magnetic trigger type, there are still plenty of upgrades that are possible without going all the way to Plasma. I know a great trick for MAgnetic trigger distrubitors, involving replacing the factory Brain, or Ignitor, with a GM HEI module. The HEI module is most always better than any stock Japanese one, and at least over here, readily available. IT does need mounted on a good heat sink, the wiring is easy. I can give detail if needed.

Hypothetically, the cheapest MSD Ignition box, the Streetfire, could be added at some point if desired, that would improve it a lot. You could fit High performance low resistance plug wires, premium cap/rotor (if available). Re-gap the spark plugs, of course. Maybe a better coil. Just using really good quality basic pieces can make quite a difference, it helps in lots of situations, cold starts, smoother running, cleaner emissions, elimination of misfires, etc., etc. Plus I found when I used top notch parts, tuneups last for Years and tens of thousands of mikes. A car I drove up to Reno last November from Phoenix AZ,(almost 800 miles) was given such a tuneup by me in the early Nineties, over 20 yrs ago. The owner, a good friend,claims it still has the same ignition parts I installed, and it has gone probably 50K miles or more. Back then I worked out of my home garage as a mechanic, and did many tuneups and carb rebuilds. I don't think I ever had anyone return for any more ignition stuff besides new plugs after I did a major tuneup. The most bang for the buck is the plug re-gap, assuming the Ignition is in good shape. As Dr. Jacobs said in his book--" Your Ignition can't be too Good!"

So, Yeah, I recommend a Grooved Weber, and at least Ohm out the plug wires, and re-gap plugs. That will really wake the old Girl up!

Tracy G
Tracy Gallaway
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Nissan 1400 LDV Change from standard carb to 36 weber DCD 05 Apr 2016 03:51 #6

  • Martin Swart
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Thank you Tracy for the comprehensive answer.

I will go for the 28/36.... That should do the job...........

Will do more research regarding the jetting and so on.

Dont think I want to risk my only bit on steel though.......

Will do a good tuneup of the ignition. Well as good as I can find here......

Thanks Tracy......

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 07 Apr 2016 13:03 #7

  • Martin Swart
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Ok so I decided on buying the 32 / 36 weber Carb. Everyone recommends this carb size for the 1400 cc Truck.

Stripped it and cleaned it out.




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Nissan 1400 LDV Change from standard carb to 36 weber DCD 07 Apr 2016 14:03 #8

  • Martin Swart
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Will post better pics when its put back together again.

Did My first orange run today or should I call it my first peach run. Ha Ha. Seeing that this is South Africa and we do things a bit different around here.
I bought a golf Radiator heater tank and used that as my petrol tank.



I drove to a quiet road and disconnected the petrol pipe to the petrol pump. Then I drove some more until the truck stalled. Then I installed the 1 liter petrol tank to the petrol pump and started driving at a steady 80 km per hr That is about 50 mph until the truck stalled again. Turned around and came back. Then out again for a second time. I think that gave me a very decent figure to work with..........

Out 1 st run was 14.5km per liter - about 10 km per hour head wind
out second run was 14.9km per liter - about 10 km per hour head wind
back first run 16.6km per liter - About 10 km per hour tail wind
back second run 17.6 km per liter- About 10 km per hour tail wind
Temperature outside was about 22 degrees celsius.

Anyone care to comment please...........

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 07 Apr 2016 17:39 #9

  • Tracy Gallaway
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The increasing km/L results from first to last run...could indicate you becoming more aware of careful driving technique. Regardless, that seems a good testing protocol. I'd think the engine was already good and warmed up even before the first run. If the wind was near constant during the runs, and no traffic, I cant think of another major variable. I'd just add up the 4 km/L results, then divide by 4 for an average. Then just repeat the process later in same road area same distance, etc., for the "after" readings.

Ya just try to get as emperical of results as ya can, as you are doing!

So the Weber, is it a DGEV, electric choke? Doesn't look too bad inside. I just remembered, a (former) friend had a Datsun I think it was a 1.6L 4cyl, about the same looking era as this truck. He had a Weber on it, and it ran like a Striped A** Ape! Though I don't know details of exact engine and Weber. IF you can get jetting info for this carb/engine combo, it will save time for sure! Webers are very sensitive to minor adjustments. If you have to put a throttle cable adapter onto the throttle shaft end--don't try to tighten the retaining nut too tight, the shaft will bind. And, there is a kind of thin washer with a side tab to bend over the retaining nut, to hold the dang nut on. Maybe use two of the retainer things, that nut wants to work loose on mine! :pinch: I'd definitely recommend doing online search for Weber troubleshooting tips to save time too. These are fabulous carb's, but the devil is in the details! You aren't supposed to set the idle speed too high with the idle speed screw, to avoid exposing the idle transition feed ports. And you don't want to have to open the idle mixture screw past a certain point either. The Idle circuit on Webers is critical to get right.

Ok, I just dug out the instructions for my Weber 32/36 DGEV from Redline Webers. The idle speed screw should adjust to 1-1/2 turns MAX after touching the throttle lever. Idle mix. screw should adjust to 1-1/2 turns out MAX. It might be different for the Weber you got, you can go to redlineweber.com for more info, and there is lots of info online for these carbs. Locals if available may have advice too, I bet your gas is different from ours, for example. Another tip is-idle RPM is affected by base ignition timing, more initial timing (turn the dist. body) helps maintain enough idle RPM's, and don't forget to see that dist. advance mechanism is free, (oil) and vacuum advance diaphragm is OK. More likely issues on an old truck like this one.

Tracy G
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Last edit: by Tracy Gallaway. Reason: more stuff

Nissan 1400 LDV Change from standard carb to 36 weber DCD 07 Apr 2016 22:55 #10

  • Martin Swart
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Tracy.

This is an DGAV. Water Choke...We are not much bothered with choke in RSA as the weather is at its lowest about 4 degrees C. So our vehicles don't really need much choke....

I found some amazing info on a few sites that I will follow with tuning tips and fault finding diagrams. Also they say webers are very sensitive to fuel pressure. A good fuel pressure for the weber is a stable 4 PSI anything above will cause over fueling and much lower than 4 psi will have other issues on their own. Also they say the mechanical fuel pumps has too low pressure at idle and also has a pulsed output which does not give a steady supply to the carb. So my thinking is go electric on the fuel pump depending on finances. Apparently the carter electric petrol pump is a high volume low pressure petrol pump and is Ideal for the webers. The Carter pumps are quite expensive in RSA if you can get them.....

Tracy did you check the fuel pressure on the Subi.

Thank you for your info though. The tips that I got is practically the same as what you are describing for tuning.......

This is one of the websites I found..............

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 07 Apr 2016 23:06 #11

  • Martin Swart
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In reply to your comment about the difference in fuel consumption on the 4 runs.

We Kept the speed well below the speed limit to minimize acceleration and deceleration on all the runs. We really wanted a stable run. So all we did was pull away at a steady acceleration to 80 km/h and kept it there.

I do think the wind was more of a factor than anything. So my thinking is to compare the 2 outgoing runs with themselves and the 2 incoming runs with themselves. I will see what the wind does when we do the second round of testing and what the difference will be then as well.

We want to do a second test run with the weber installed only and after all tuning is done to whatever I feel needs to be tuned. Like checking for proper spark and to increase plug gap and doing the PCV Valve reroute if need be. Then after that test session I want to do the groove and retuning of the carb and then we will see what effect the groove has on the Fuel economy and the power output...

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 07 Apr 2016 23:44 #12

  • Tracy Gallaway
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OK, that's cool. Though even if choke isnt needed much, it's still good to have fast idle RPM function on cold starts, IMHO. Yes Webers want low constant fuel pressure, my info says to limit to 2-3 Lbs pressure. My sources also strongly recommend a Weber fuel pressure regulator. On the Subie, that's one part I still need. I had another one that leaked and was discarded. I haven't checked fuel pressure, my bad. The Webers can do very well, but require correct setup/tuning.

Tracy G
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