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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 22 Apr 2016 15:13 #37

  • Martin Swart
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Hi Greg.

The throttle plate is quite thick. I might try to shape it at a later stage. At the moment we have enormous power all through the torque range. It is a four speed. This little truck runs in fourth gear all over town and believe me when I say we have some really steep hills here. I tested it yesterday. One street is so steep that most cars need 2 nd gear to drive to the top. I started of from standstill at the bottom of the hill and ended at the top on 60 km/hr. The most amazing about this was that I pulled away in third and never changed gear.... Power to weight ratio is amazing at the moment in my view.

Tracy.

My fuel test runs..............

First run with the old carb...........
out wind from front average 14.7km
back wind from the back average 17.1

second run 32 36 Weber without air filter

out same road as first runs this time wind from the back... 16.3 km/lit
Back wind from the front same road.........................17.6km/lit

third run 32 36 Weber with the groove and spark plug modification including new air filter no change to the jetting.......exhaust smells clean and lots of torque. The groove is working

out same road as first run wind from the back again........16.3 km/lit
back same road wind from the front.........................16.9 km/lit

Next I want to do rejetting.......I am a bit in the dark here. Obvious at the speed we are driving I dont think we hit 3000 rpm. I read on the weber sites that the 32 36 weber has a Idle jet and that the idle jet supply fuel up to about 2800 rpm. Now my question. Do I change the Idle jet or the primary and secondary jets to lean it out. Second question. I seem to be struggling to make out on the plugs whether I am too lean or just right. The initial jetting was lean and the plugs got a reddish powder coat on it. At the moment my feeling is it can be leaner but because of the dirt on the plugs I can't be sure. Any advice regarding to be sure not to go too lean...........

Lastly some pics of the final product......





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Nissan 1400 LDV Change from standard carb to 36 weber DCD 22 Apr 2016 15:49 #38

  • GregK
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Those results put that truck slightly over 40mpg post modification.
Awesome!
At this point all that remains is to tweak until it's stable and reliable; you may luck into the magic formula that takes you over the 40 in doing so.
Do I recall correctly that this is an older relation's vehicle? What do they think?

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 22 Apr 2016 19:35 #39

  • Tracy Gallaway
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Ystervark--that engine bay and truck is Awesome! :evil:

My Gawd that is a sanitary job you did there! I'd tell the Owner that if there is an online or other collector group for these trucks, he should join that group and post about it there, with pics! Jeepers, that is such a nice clean simple engine and engine bay! We here can only look on with fond nostalgia for one such as this. I bet Karl Britz will weep at the sight of this... Martin, you truly do awesome work, friend! ;) That air cleaner, duct and carb hat are very attractive on this engine, and super functional as well. I wanted to do something like this for my Weber on my Subie, but hood clearance is lacking. Congratulations on an outstanding looking job!! :woohoo:

Sounds like you hit another one outta the park! Loads of power, fat torque, great economy, and a clean smelling exhaust too... :oops: I'm blushing with envy here.

Jetting- it sounds like it's already close. I mean with no cat. converter, and it smells clean. Is there moisture on your hand when cupped at the tailpipe at hot idle? IF it smells clean and it's moist, you are pretty spot on for idle. If you drive it on the road w/ the window down, and still never smell a stinky exhaust, even better. The reddish plug deposit, that might be a fuel related deposit. Were the plug tips clean when you cut and gapped them? My experience says to watch for white plug tips as a sign of lean ness. Especially to watch for tiny speckles of white/silver dots, that can be aluminum being burned off the piston tops. But, if it starts easy, never pings, has a smooth idle, and just wants to GO anytime you want. AND the exhaust always smells clean... I'd say you are There.

But, you can still try to play w/ the idle jetting some just to see. Maybe one step lean on Primary idle jet, minding Weber's recommendations for how many tuns out from closed for idler mix screw.. And Weber's recommendations for how many turns in after first contact for the idle speed screw. Webers are sensitive to the adjustments for idle speed and idle mixture screws. Now, I have no idea what jetting is all around for this Weber. As for my 32/36 DGEV, out of the box new, my Subie had incredible power, but it was pretty rich. Black plugs and smelly exhaust. I had to lean out virtually all the jetting. The other thing, is Weber strongly recommends one of their own fuel press. regulators, info here in USA says no more than 2-3 lbs/inch fuel press. As I said earlier, I used a generic cheap one from a parts store, but it eventually failed and leaked. I need to get a Weber one.

From what you say Martin, I think you are close. Careful tweaking, keeping record of each step, one thing at a time, and you can wring more economy from this sweet truck. You folks in SA may have better gas than we do here. I remember one brand of gas additive would cause reddish plug tips, don't remember which one it was, haven't used it in years anyhow. If it is a light brown/tan color, that is considered optimal here with a carburetor, but our gas is spiked w/ Ethanol, so plugs are usually close to white most times now. The fact that the test run results are so close on the original and the Weber, suggests the Weber may still be a little rich, but go slow with the jetting. Do you have a good source for jets there?

BTW, Martin, you have had at least 5 Groove Victories now, right?

I believe that makes you an Ace! :evil: :woohoo: :lol:

Tracy G
Tracy Gallaway
Founder and Constant Aide to Gadgetman
Gadgetman Reno, NV

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 23 Apr 2016 12:26 #40

  • GregK
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Hold on a second; did I read your results correctly? You achieved higher mileage with headwinds, driving into the wind??

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 26 Apr 2016 13:40 #41

  • Martin Swart
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Yes Greg. The road is not flat so there are hills also that influence the result.........

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 26 Apr 2016 15:31 #42

  • GregK
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So downhill and possibly some air forced in past the groove IMPROVED economy/efficiency... Hmmm... I wonder if there's a way to investigate/isolate that latter factor so that you could make it more consistent? Tracy's on the right track with jetting I think...Or you could find a way to present a larger, denser air mass to the groove to enhance the vortex/waveform. Both would work to lean the mixture.

Is that intake tube the same length on either side of the bend? Would reversing it have any effect?

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 29 Apr 2016 10:57 #43

  • Martin Swart
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Greg and Tracy.

We changed to smaller jets today. Will do some testing tomorrow. The spark plugs are showing black carbon.. I think that means we can lean it out a bit........

Greg. I can not think of any way to take the wind factor out of the equation ..........

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 29 Apr 2016 12:05 #44

  • GregK
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Wind factor - yes, you're right. You'd have to stop the sun from shining AND the earth from rotating B)

But what about reversing that new intake tube so that the long straight part is between the bend in it and the TB? Is that possible? Does it make a difference if you can? Is my perception from the pic incorrect?

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 29 Apr 2016 19:18 #45

  • Tracy Gallaway
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Hi Martin-- I had black carbon on my plugs as well when I first did my Weber conversion. So yes, jet down some, and this will boost economy too. Takes time to sort out, but when the exhaust is cleaner, and plugs read a tan color, you are about right. BTW, Did you know of the Colortune spark plug for carb. tuning? It's from England, you only use it in the shop/driveway, not on the road, it allows you to see the combustion flame color. I don't have one, but there are online videos of it to watch it in action.

For an ideal Orange test, you want miles/KM of as flat and straight a road as possible. Then ideally with little/no traffic, and no wind either. Test track conditions, removing as many variables as can be done. I have such a road about 35 miles East of here.

You're on the right Track, Ystervark!

Tracy G
Tracy Gallaway
Founder and Constant Aide to Gadgetman
Gadgetman Reno, NV

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Nissan 1400 LDV Change from standard carb to 36 weber DCD 05 May 2016 23:46 #46

  • Martin Swart
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Tracy.

Thank you for the input. I heard about the colour tune plugs. Did not see any on the shelves here though.....

Greg.

I did consider the suggestion to change the intake pipe around. I feel I spent enough time on this vehicle and apart from the initial gains we got I could see any improvements whatsoever on other modifications.

I feel its time to call it a day on this one. The owner is ecstatic about the torque gains and he is ok with the fuel economy improvement. The way he drives might show way more economy improvements than we expect. He drives 40 KM/h in one gear normally too high of a gear. In this case he can even use 4th at 40 km/h and he will still have lots of torque to work with. So my expectation is that he would save more fuel than the tests showed...........

Lets wait and see............

On to the Golf.............................

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