Niva Weber Swap

The Lada carburetor shares its footprint with the downdraft Weber family, which means that you can easily install the famous Weber on to your Niva. Although the Lada carburetor is not nearly as bad as many people make out, the Weber is a newer design of the carburetor and more importantly has bigger barreled throats (ie allows greater air-flow), so the upgrade is recommended by many for better power and drivability.

Nivas also benefit from a larger bore exhaust, while it’s an expensive upgrade whenever your current exhaust needs replacement consider replacing it with a 2” system instead (don’t go any bigger though or you’ll likely loose useable power).

A Weber will generally not drastically improve a Niva's mpg (depending on the Weber and how you drive it may even make it worse). A decent condition Weber will certainly improve on the mpg of a worn or badly tuned original carburetor, but one in poor condition or tune will not help.

NOTE: I've currently reverted back to an original carburetor because all of the suitable Weber DGVs I have (annoyingly except one which has a mystery problem I can't solve), and most second-hand ones for sale nowadays, are simply worn out.

The Niva had two main types of carburetor fitted: a mechanical opening secondary or a vacuum operated secondary. Webers are virtually a direct swap onto Nivas originally fitted with mechanical secondary type carburetors. Nivas originally fitted with a vacuum secondary type carburetor may require a custom linkage lever for the Weber. Left-hand drive Nivas have different linkages I'm unfamiliar with, but I believe they are either easy to mod or a direct swap (there are some photos below of LHD set-ups).

Niva's AvtoVaz carb - the disc shaped housing partially hidden on the left shows this is a vacuum operated secondary model

 

Which Weber for my Niva?

There are many Webers in the D family that will bolt on to a Niva. Three main factors should dictate what Weber you choose: Size/jetting (a Weber from a 1600cc motor will have jets and venturis closer to the correct sizes for a Niva), Ease of fitting linkages, air-box, choke, etc, and most importantly for many - Availability (ie what you can get at what price).

Weber DG

The Weber DGV family (DGAV, DGEV) found on many ‘70s and ‘80s UK and European Fords (eg 2-litre Cortinas and Sierras, and GT Escorts) and many other Euros is probably the most commonly available Weber downdraft, and is a realatively easy swap onto a Niva. You can probably even get a DGAV etc quite easily and cheaply off a running motor (that way you can see how well it runs). They come in two main sizes, the 32-32 DGAV off 1300 & 1600GTs and the more common 32-36 DGAV off 2-litre pinto powered Cortinas and Sierras etc. Note: a DGEV is a DGAV but with an electric choke ('E' for electric) instead of the DGAV's hot water operated choke ('A' for Aqua). Webers are also available with manual cable operated chokes, DGV.

Weber DGV Niva swaps (click on image for bigger view)

The bigger synchronous opening models (ie both barrels open at exactly the same time rather than progressively), 38-38 DGAS/ES, 40-40 DFAV (fitted to V6 Capris etc) and DPS (sort of a bigger version of the DGV), will fit pretty much as easily as a DGAV. On most cars the DFAV and DGAS give better low torque and initial response than a DGAV at no big cost to economy, but they are probably too big to be suitable for a Niva.

Weber DGAS synchronous monster on a Niva - I'm testing a 40/40 DFAV at present... (click on image for bigger view)

My initial trial of the DFAV 40-40 was surprisingly promising on road (big torque improvement), but it could not do low engine speeds under load at all well (eg you can not crawl up a steep incline, it has to be floored instead), and off-roading it consistently floods on steep inclines that my smaller DGAV had no problems with. Though I didn't play with the jetting or floats to get it running optimally, and I may have have had other tuning issues.

Weber DC

The older Weber DCD (as fitted to '60s UK/Euro GT Ford Cortinas etc) can be fitted almost as easily. But although they are better built than DGAVs, they're probably no better design than the Lada carb. However, they also have the advantage of larger venturis than the Lada carb (btw DCDs have swapable venturis for different sizes). Also DCD's don't have a power-valve like the DGV (though as you'll see this isn't necessarily a bad thing for off-roading). There is also a vacuum secondary version, the DCHE (Fiat 125 etc), which I have tried. They also don't appear to have diaphragms or o-rings to perish like a DG.

The DCD should be as easy bolt on as a DGAV. Its choke cable is identical to the Lada's and will go straight on, but you'll need a new throttle lever as the one on the DCD is about 90 degrees out, like the DGAV you can make or but one to suit, or maybe adapt the Lada one. Also like the DGAV you'll also need to modify the floor of your air-box and/or make an adapter, as the pattern is different and it needs to be a few cm higher to clear the brass filter housing. Also you'll need to find a vacuum feed for the Lada's engine breathing system (my vacuum secondary DCD has a suitable port, but the mechnical secondary DCDs don't appear to).

Weber DCD - a goodie, but an oldie

Weber DF & Friends

The Weber DFV family (DFAV, DFEV) are essentially a reversed version of the DGV where the left barrel is the primary instead of the right (eg for applications where the carby sits on the left side of an engine). DFVs were fitted to '70/'80s Fiats, VWs, Renaults etc, and will also bolt to the Lada manifold. DFVs have the advantage of the air-box mouth being a similar shape as the Lada (see below). A vacuum secondary version, the DFH, is available.

Weber DFVs (click on image for bigger view)

The American Motorcraft / Holley 5200 family (fitted to US Pinto & Iron Duke motors, in Chev Vega/Chevette, Pintos, some Jeeps, Chrysler '70s 4 cylinders, and a G180 version to some 2 litre Escorts and Cortinas in Australia), is a licence built DFV copy, and is a similar carb and will also fit.

Chevrolet Chevette sourced Holley (ie DFV copy) Niva swaps (click on image for bigger view)

However, the reversed pattern means DFVs typically have the secondary and primary barrels swapped around, making things in the wrong place when fitted to the right hand side of an engine. These can still be fitted to a Niva but on right-hand-drive Nivas they will need a custom linkage bracket and lever to operate the left barrel, and probably a manual choke conversion (as wet-chokes may foul the cam box), and will be slightly difficult to get to the mixture adjuster.

Weber DR

The Weber DIR and DAR (which look very much like variations of a DFV to me) as fitted to Renaults (eg Renault 16 - 1.6 l L / TL; Renault 18 - 1,6l TS/GTS - 2l TX/GTX Renault 18 - 1.6 L TS / GTS - 2l TX / GTX; Renault 5 - Alpine (non turbo) Renault 5 - Alpine (non-turbo)) seem to be a popular Niva swap in France. If you can find a manual choke version it will make for an easier swap. Some R25s have a snorkel top for the DIR which would be handy to also use if you want to relocate the air-box.

Various Niva Weber DIR Niva swaps (click on image for bigger view)

Other Webers

The DMS, ADF/ADL ('60s/'70s Fiats & Lancias) also bolt to the manifold, though they both have the DFV's 'reversed' barrel layout and will need the same linkage solutions. The ADF has the choke linkage above the throttle linkage, so wet-chokes won't have the same clearance issues with the engine as a DFV, and it looks like the Lada air-box would be easy to adapt to fit to the ADF.

I've never seen a DAT/DATRA/DHTRA (Fiat X1/9, some 128 and 124s), but it's reported to be an easy swap for a Niva. Though looking at a couple of pics on the 'net at what I think is an X1/9 carb, they appear to be 'reversed', have a different mouth, linkages etc, so potentially much more work than a simple DGV swap.

FIY, the 32 DFM or DFE off some Cortina and Capri 1600 GTs or GTEs is probably one of the most suitable 2nd-hand Webers for a Niva (though likely ultra rare nowadays), as it's jetting should be pretty right for a 1600, it has an oval style mouth so the Lada air-box should be easy to adapt on (and I assume they have the DGAV linkage and choke layout - though I haven't seen one for years so I could well be wrong and they may be the DF family 'reversed' layout).

If you have a choice of '70/'80s Webers try to avoid the "Made in Spain" Webers common on many Euro Fords if possible; back in the day they were generally believed to be of inferior quality to the original "Made in Italy" Webers (note all Euro Webers since 1990-something are Spanish made).

Other non-Webers

There are also other makers of carburetors that fit the Weber footprint (eg the Solex 2-barrels fitted to some V4 Saabs, some BMWs, Alfas, Peugeots, etc), or that are unofficial Weber copies (eg the Chinese EMPI EPC 32/36). The Solexs are often themselves replaced with Webers as an upgrade so generally a Solex will not be an upgrade on a Lada carb, unless perhaps you get one with bigger venturis. The EMPIs I know nothing about but if they are of reasonable quality might be worth a look.

Solex 34 (from a Peugeot 504)

 Solex two-barrels will also bolt to the manifold, but probably no real improvement

Mechanical or Vacuum operated secondary barrel?

Most Webers have their secondary barrel opened mechanically by a lever that is operated progressively by the lever on the primary barrel. But some have a vacuum

operated secondary; ie the second barrel only opens if there is vacuum demand from the engine to need it open.

Both will fit, and both have advantages. Webers with mechanical opened secondary barrels (eg DGVs and DFVs etc) are better for outright performance, but Webers with vacuum operated secondaries (eg on some Fiat sourced Webers, eg the ADHA or DMHA) are probably more reliable off-road and for economy, though in my experience annoyingly lack power in some situations.

A DGV's power-valve can pump too much fuel for low vacuum conditions like a slow crawl up a steep hill. Using a vacuum secondary Weber (or possibly even a non-power-valve model, or changing the power valve spring) can also help avoid the power-valve at low vacuum issue, as the second barrel will close during low vacuum conditions and thus help avoid flooding during low speed crawling. A Weber that has too much air-flow will have similar problems.

The 'H' on a Weber's name means it a vacuum secondary (I think?); eg the DCHE is a vacuum version of the DCD, and the DHS is a vacuum version of the DMS, the ADHA is a vacuum version of the AD. As far as I'm aware there is not a vacuum version of the DGV though. You can tell a vacuum Weber as it will have a solid disk-like mechanism on the linkage side (eg like on the left the Lada carby picture at the top of the page).

On step forward angles the Weber is also known to flood itself by either emptying fuel out of fuel bowl into the chokes. There are also several simple mods to avoid the flooding over into the chokes issue (eg snorkels, rotating the carb through 180 degrees).

With a small amount of testing my stock 32-32 DGV or 40-40 DFAV has never had this problem with emptying fuel into the chokes on steep hills (perhaps I'm just not trying hard enough :) ), but the 40-40 DFAV refused to low-speed crawl up steep hills (it's probably simply too big venturi for the vacuum in a Niva engine at low rpm, though I have other undiagnosed engine issues it could also be).

Fuel Supply

Most Webers run on between 2.5 to 3 psi fuel pressure, I'm unsure what the Niva pump's exact pressure is, but it seems within this range.

Fuel Lines?

Some Webers have a return fuel line to the fuel tank, and some do not. Likewise some Nivas have a return line and some do not (depends what age your Niva is and what market it was built for). Check your Niva and ideally get a carby with lines to suit, though the Weber can be changed if necessary (ie block the Weber's return line feed if the Niva hasn't got a return line and your new carby has).

Air-box to Weber Mounting?

See below

Jetting?

Carburetors have internal jets to meter the fuel and air ratios. Different applications of carburetors have different jets. So if you can get a Weber from a 1600cc motor instead of the 2-litre its internal jets and venturis will likely be more correct sizes for the Niva’s engine.

If you just use a Weber jetted for a 2 litre it will likely run to rich, which will not only cost you money and power, but can lead to reliability and engine wear issues (I am told Ford 2-litre sourced Webers can be easily re-jetted for a Niva by opening up the air-corrector jets "one drill size" (which I assume to be 2mm). Not elegant, but as bigger air correctors mean leaner up top and the main jet starts to flow earlier I could see that it may work well).

Conversely if your carby is running too lean, you'll risk burning pistons or valves.

If you need to fully re-jet a Weber, fitting new jets to a Weber is fairly easy. The dark art of course is in knowing what sizes are right - there are some jet sizes below for Webers on Nivas. I'd be grateful to know if some one has used an oxygen sensor to determine optimum jet settings for a Niva?

I originally choose a de-choked DGAV 32-32 because I had it lying around and I suspected it was already jetted for a 1600cc engine, as opposed to the various 32-36 DGAVs I have off 2-litre Fords. This worked well when it was in good condition, sadly (like many old Webers) its shafts have some wear allowing air past making it dufficukt to tune correctly.

Check it's Condition

If buying a used Weber check it for worn throttle shafts, this is the only real weakness Webers have that is a serious problem to correct (try to move the shafts side-to-side & up-and-down, they shouldn't have very much play at all (eg 0.2mm), too much play will ideally require rebushing or it will leak air and effect the mixture. I always pop some light greasy type lube on the shafts before fitting a Weber; it's probably pointless as fuel likely washes it out, but it makes me feel better. :)

Then, unless it's come off a good running engine, it'd be best to give it a quick check over that the jets and valves aren't blocked etc, and the diaphragms are not stiff or leaking (here's a good guide ). If necessary reconditioning kits are easily available. Tip: make sure you don't get your jets mixed up.

While it's apart it would also pay to check that the float level is correct. The float valve and float are in the top cover. Redline Weber recommend DGV float settings to be 38.5/46.5mm (plastic float), and for aggressive off-road float drop should be limited to 44.5mm maximum drop. Weber North America advise 35/51mm for plastic floats with F50 emulsion-tubes, or 36.5/46.5 if using an F6 emulsion-tube. Note that the older style brass floats have different settings to the plastic floats at 40/50mm (Redline), 39/50mm (Haynes), 41/51mm (Weber North America). Plastic floats are better off-road (less bouncy), and more reliable (can't spring a leak).

Brass vs plastic float settings for 32/36 DGV on a Formula Ford race car (click on image for bigger view). Note these are for an engine that spends its life at top RPM and on a flat surface - see above text for suggested 4x4 settings.

 

Need to Recondition your Weber?

Here's a handy step-by-step guide with loads of pictures.

 

Let's Bolt It On...

Mounting the Weber is easy. The Lada carb is removed, new gasket, and the Weber bolted on instead.

My Niva is the only car I've had heat issues with a DG Weber (probaby because it's the only Weber equipped car I've had with the exhaust on the same side as the carburetor), so I used fibre thermal spacer blocks between the carby and the manifold to stop heat-soak from the manifold, any less than 2 spacer blocks and it suffers from boiling the fuel in the bowl. Remember to use new gaskets between the blocks themselves and the manifold and carby (vacuum leaks will make it run badly and make other problems difficult to diagnose). I also fitted a metal heat-shield (from a Ford Sierra) that shields the fuel bowl from exhaust manifold heat. Re-routing the fuel line away from the radiator and radiator hose is also a good way helping keep the fuel itself cold.

 

The Throttle Linkage Lever

I believe the mechanical operated Lada carby linkage lever is a direct swap onto a DG family (ie it's essentially a straight swap). Nivas originally fitted with vacuum carbys like mine will need a linkage lever made or adapted (or perhaps obtain one from a mechanical secondary carby Lada). The Lada throttle cable bracket fits right on the the DG Webers linkage.

My Niva originally had a vacuum operated secondary carby so its original throttle linkage is different to the DGAV's, and I had to make a linkage lever to fit the Lada’s throttle cable (see image below).

I originally adapted a linkage lever off a Japanese carby I had lying around. A simple matter of cutting it to the right length (too long or short and it will open the carb either too quickly or not open it enough) and drilling/filing a hole to fit it on the Weber’s throttle shaft (and be careful not to over tighten the nut that holds this lever on, it only needs to be a little more than finger tight).

It's the same as part 'B' in the Weber's Lada conversion kit below, but turned through about 180 degrees so it works with the original Lada throttle cable bracket (ie pulls the lever from below) instead of the custom throttle cable mounting bracket that is part of the Weber Kit (ie pulls from above).

Baxter's DGV set-up (version 1), using Lada bracket and custom linkage lever (click on image for bigger view). Bending the pipe and grinding the bracket can be avoided by simply cpacing the btacket upwards until it's above the pipe.

I've since bought a Redline bracket and multi-position lever kit (About NZ$18 at BNT), which is great as I can use it for various Webers set-ups.

Throttle-cable Bracket

I originally also made a replica of the Weber kit's throttle-cable mounting-bracket, but found the Niva's throttle-cable was too short to reach the bracket properly (I'm guessing the Weber kit I copied is for left-hand-drive Nivas).

So I instead used the original Lada bracket and cut a small slot in it and slightly bent the brass pipe vacuum advance line feed on the Weber so they did not foul each other (see image above). It's probably easier and neater to simply space the bracket

upwards until it sits above the pipe (of course I only thought of this after breaking 3 or 4 brass pipes trying to bend them...).

Left: Standard (vac op) Niva RHD linkage - Right: Weber DGV using Niva RHD bracket set up (click on image for bigger view)

 

Alternately, you can (or at least used to be able to) buy a Lada specific kit (see image below) with all the linkages, cable mount (not shown) and choke adapter, or a generic Weber fitting kit.

Weber's Lada conversion kit (click on image for bigger view)

Left-hand-drive Nivas have a rod linkage instead of a cable. I'm unfamiliar with the LHD linkage, but I understand it is easy to fit to DG Webers (presumably by altering the length of the adjustable rod to suit).

Left: Standard (vac op) Niva LHD linkage - Right: Weber DGEV using Niva LHD linkage (click on image for bigger view)

Modifying the Lada Air-filter Box

DG

The Lada air-box will not bolt to a DG family Weber without modification. The DG family Weber has a square-ish mouth where the air-box bolts on, which is different to the Lada air-box's oval mouth. If you use a DGV or similar you'll need to either make/obtain an adapter (like in Weber's conversion kit, parts 13 and 14 in the picture above), or modify your Lada air-box's floor to fit (like I did, see below, but the Lada air-box sits too low to fit with a wet or electric choke),

The simplest solution is to use an ugly plastic Ford Cortina or similar air-box that hopefully comes with your donor Weber (as a bonus you'll get the advantage of a bigger air-filter), they willbolt to each other nicely and there will be room for the choke. FYI, the Cortina air-box will fit a Weber DGAV equipped Niva nicely, but the Sierra one will not fit as it has a bulge that fouls the cam cover.

Cortina air-box is probably the easiest solution for a DGAV swap. But not elegant imho.

I wanted to retain the Lada’s factory air-filter box to keep things looking factory, and so the Niva's oil breather hose would plumb right up. So I trimmed the hole in the base of the air-box to fit the DG family Weber. I cut some foam and rubber to shape to ensure an air tight seal between the air-box and the Weber (and as I originally had no choke I also blocked the hole for the choke lever with some cold solder).

Part of the Lada’s air-box sits slightly lower than the surface were it mates to the Weber so its floor needs some panel-beating to make it clear the front of the Weber

(make sure the air-filter still seals if you do this). The Lada air-box also interfered with the wet/electric choke mechanism so I removed the choke mechanism (with a plan of converting it to a manual choke later).

To avoid modifying the air-box you could make a much thicker adapter seal between the carby and air-box to space the air-box upwards (be careful not to foul the bonnet though). Or better, find the Weber-to-Niva air box adapter (part 13 in conversion kit image above) in the kit and you’ll avoid this hassle.

DCD

The DCD has a square mouth, but is different to the DGs (its bolt pattern appears to match the base of the carby), and the brass filter nut on top of the float chamber sits proud of the bottom of the Lada air-box which needs to be accomodated.

DF

The DF family is a potentially easier swap in this respect, as the DF has an oval mouth similar to the Lada's; though its oval is a pointier oval that the Lada carb's, so the Lada air-box will still need some trimming if you want to retain it. Many of the other Fiat sourced Webers, eg ADF, have a less pointy oval mouth that better fits on the Lada air-box (eg may need only minimal trimming).

NOTE: when making adapter plates make sure you don't inadvertantly block off parts of the carb than need air (eg the jets etc), this is easy to do on a DCD.

 

The Choke

If your Weber has a manual choke the Niva cable should fit straight to it. If your DG Weber has a water or electric operated choke you can plumb/wire this in, but it'd be wise to check it's working properly first.

If you do choose remove the wet or electric choke, remove the choke flaps as well (unless you’re converting to cable operation), and don’t forget to block off the vacuum feed to old choke mechanism (I have used this vacuum port to supply the Lada engine's breathing system in one instal, ie the same set-up the Lada originally had).

Currently I have no choke at all, and it starts and runs cold fine (probably a sign I'm running too rich). However, I would like to add a cable operated choke in the future. Kits used to be easily available to convert water and electric choke Webers to be cable operated, but make sure they won’t foul the Lada air-box if you're retaining it.

Manual choke adapter kits like this should be perfect (click on image for bigger view)

You could convert a wet or electric choke to be manual like this, but as I recall such conversions never worked satisfactorily.

 

Breathers

The Niva has 2 engine oil breather hoses that come from near the oil pump and feed into the intake system. The smaller hose (number "8", the smaller hose that connects near the base of the engine's dip-stick) is the vacuum supply for the oil breather and is plumbed into the Lada carby (before the throttle plates iirc), and a large hose that connects that supplies filtered air to the oil breather, which is plumbed into the air-box.

I've left the large breathing hose plumbed into the Lada air-box in my swap (one advatage of retaining the original air-box).

In version 1 I re-routed hose "8" (the smaller hose) into a spare vacuum line in the inlet manifold (via a charcoal fuel filter, see below image). This worked, but as this was after the throttle butterflys it was potentially acting like a vacuum leak in the engine's intake, also others have had problems with no.4 spark-plug being oiled using this set-up. In version 2 it is routed into a suitable port in the Weber.

Baxter's breather hose "8" set up (version 1, which has issues - see text) - In version 2 I re-routed hose '8' into a vacuum port on the Weber (the one originally used by the wet-choke) so it is before the butterflys rather than after.

I've also tried located it in a fibre plate that allowed a vacuum to be taken from directly under the Weber (which I assume was originally used to as the vacuum feed for the brake servo in a V6 Capri that the plate came off), but this also essentially a vacuum leak in the intake. I've tried plumbing it with a T-piece into the vacuum supply for the distributor instead, but this wasn't ideal as it weakened the signal to the dizzy.

The best way I've found to copy the original breather set-up is to plumb hose "8" from the vacuum supply for the DG Weber's wet-choke (I don't have a wet-choke fitted meaning this vacuum port is free). This appears to work like the original factory set-up.

Exhaust Gas Recirculation (EGR)

The EGR system still can be hooked up with the Weber. But as the Niva's EGR is largely ineffective most people simply block it off. Odds are yours probably already is.

Tune It Up

Now set up the idle and mixture (see Tuning Webers below), and you should be good to go...

Handy Tip - make sure your timing, gap, plugs, points, valves are all set right before doing a carby swap, and there's no vacuum leaks before you tune it. I never do - and it always makes trouble-shooting and tuning unnecessarily difficult.

Weber trouble-shooting guide (500K)

Exploded Weber DGAV/EV diagram and parts list

What do all the jets do - Weber circuits diagram

Redline's DGAV/EV off-road float chamber settings (make sure you get the right settings for brass or plastic floats - they're different).

-Baxter

 

Various advice from the ‘net:

 

Tuning Webers

Adjusting mixture:

Note: Before adjusting carburetor, be sure engine is at operating temperature, (choke fully off) air cleaner is removed and vacuum lines are plugged off. 1. The Weber DGV/DGAV idle speed screw should be adjusted to its preliminary set point before adjusting the idle mixture. To set the idle speed screw, follow these

steps. 2. Back "out" the idle speed screw until the tip of the screw no longer touches the throttle lever. Then slowly turn the screw in until it just comes in contact with the throttle lever. 3. From the "contact" position, turn the idle screw "in" one (1) full turn. 4. If a tachometer is available, install it prior to starting the engine. If a tachometer is not available set idle mixture "by ear." 5. Start engine, be sure choke is not engaged, and proceed to adjust the idle mixture.

6. Turn the idle mixture screw "in" (clockwise) until the engine RPM begins to fluctuate on the tachometer. (If adjusting by ear, until a noticeable drop in speed is heard.) 7. Back "out" (counter clockwise) the idle mixture screw slowly, until the engine idle becomes steady. Try to obtain the leanest setting without affecting the idle speed. If necessary, repeat steps 6 and 7 until the best setting is achieved. 8. Once the mixture is set, fine-tune the engine's idle speed, if necessary, by readjusting the idle speed screw. (Note: Turning "in" (clockwise) the idle speed screw will increase engine speed. Turning "out" (counter clockwise) the idle speed screw will decrease the engine speed.) 9. If idle speed is reset go back and repeat steps 6 and 7.

When adjusting understand the need to keep throttle plate adjusted as near to closed as possible so as not to prematurely expose the transition holes and artificially increase richness.

It's a good idea to make sure that there is little to no off-idle hesitation which would indicate a lean mixture. The accel pump in the Weber should prevent that, but sometimes, its possible that your final mixture setting is on the lean side and so you might get some hesitation. If you do, turn the mixture screw out just a hair, like 1/16th of a turn and then run the engine at 2000rpm for about 10 seconds and then let it idle. Now snap the throttle open quickly. Hesitation? No, great, you're done. Still some hesitation? Make another 1/16th turn out and repeat.

More Weber tuning info here and here .

 

Jetting

Fitting new jets to a Weber is fairly easy; the dark art of course is getting the sizes right...

 

Robin Both's (aka Niva Nuts) Weber 32/36 DGEV Jetting Table for Niva 1.6

Part Primary Secondary

AUXILIARY VENTURI 3.50 3.50

MAIN JET 1.40 1.40

IDLE JET .55 .45

EMULSION TUBE F50 F50

AIR CONNECTOR JET 1.70 1.40

ACCELERATOR PUMP JET .50 -

"I have successfully installed the Weber 32/36DGEV with the above specs, and it's running great." - Andre Lukatsky (LadaUSA forum).

Hoodoo on Niva Ford sourced Weber jetting:"Set it to 5deg BTDC. If you push the choke in early, it will backfire as the mixture is too weak. If the Weber has the original jets, it is probably a 127 main and 130 secondary. Change to 130 main and 135 secondary and you'll lose the flat spot you may well have when pulling out of junctions." Hoodoo (lada.co.uk forum).

Andrew on Niva Weber DGAV jetting:"The complete solution involves the air jets, emulsification tubes and fuel jets. Chances are you have 165 primary and 180 secondary air jets which should be fine. Without a doubt the best emulsification tubes to use are F-66. Chances are you have F-6. Do yourself a favour and change, it will greatly improve the low rev performance. If you do use F-66 emulsification tubes than you don’t need to go any bigger than 132 main and 127 secondary fuel jets. I have found that with the Weber I need to run about 12 degrees static advance to get optimal performance/efficiency. As mentioned above too much static advance will cause pinging and eventually engine damage. To be able to increase the static advance without getting pinging at higher rpm/high vacuum, it is just a matter of putting some more tension of the advance weight springs to achieve to "normal" total advance.From my experience you will definitely want more than 5 degrees static advance. This will cause pinging problems. There is a simple way to reduce the mechanical advance of the distributor to fix this. Also the carby setup above uses F50 emulsification tubes, these are the leanest available. So larger jets have been used to make up for this. It is my experience that running richer (F66) emulsification tubes with 127/132 jets will yield better bottom end drivability whilst maintaining the same top end."

Jokari from Finland on Niva Weber 32-36 DGAV jetting:

If I understand the translation correctly Jokari used a wideband AFR meter and a lot of time to determine these settings; his Weber conversion gets 10L/100km around town and a best of 8.2L/100km, with good torque from about 1800rpm and peak torque at 2400rpm, on his otherwise standard Lada 1600 saloon (ie lighter than a Niva) using:

F50/F6 Emulsion tubes3.5/4.5 Diffusers150/150 Mains170/190 Air-correctors55/80 Idles

These look potentialy a bit rich to me (and maybe I've cocked up the translation?), but he specifically tried 140 & 145 mains and found them too lean - and an AFR never lies. So these may be the most definative jet settings for a DGAV on a Lada engine.

 

 

NivaAdventure member on Niva Weber DIR jetting:

"This table here is the best setting for a DRT 32DIR (nozzles 23 and 24), that being said a 32DIR (23/24) with the Russian jets works well." (Guerchais)

Unknown on Niva ADHA (ie vacumm secondary): "Primary main fuel jet 125, primary air correction jet 175, secondary main fuel jet 155, secondary air correction jet 195. Primary idle mixture screw is out 2 1/4 turns, secondary idle mixture is out 1 7/8 turns."

 

Which jet is which?

The idle jets are in holders on both sides at the top of the body ('g' in the above diagram). The air-corrector jets are in the body in the centre on the top ('a' in above), the emulsion tubes are directly beneath the air jets, and the main jets ('Gg' in above) and power-valve are in the bottom of the float chamber. The secondary venturis (or difusers) are the things that sit in the venturis ('C' in above). The accelerator-pump jet is the little aluminium V-shaped part overhanging into both venturis, with a valve underneth it.

How do I know if my jet is too big?

"If the mixture screw's sweet spot is more than 2 1/2 turns out turns then the Idle jet is too lean (ie too small). When the mixture screw is less than 11/2 then the Idle jet is too rich (too large). These assumptions are based on the fact that the speed screw setting is not opened more than 11/2 turns. If the speed screw has to be opened 2 or more turns then this is also an indication of a lean condition usually requiring greater change. At times it may appear to be showing signs of richness or flooding it is really a lean condition.

EXAMPLE With the speed screw set at no more than (1 1/2) turns in after contact with the stop lever; and the best idle occurring with the mixture screw set at 3 turns from bottom, indicates the need for a larger Idle jet. Achieving the best idle at under 2 turns indicates the need for a smaller idle jet."

Ford sourced Webers on the Niva

"The Weber in your Photo looks like either a DGV or a DGAV Weber. They most certainly will work on the Niva's, but do be warned that in certain situations (slow, steep uphills) they can have a flooding problem, due to the power valve, and anti stall valve designs. They fit best on Niva's that came with the mechanical secondary, knock off Solex carb, and the linkage requires almost no modifications. Weber chokes work just fine in either water heated, or electrical forms.(you can actually fit the electrical pod onto a stock Niva carb. The problem with fitting up a manual choke as described by Lada Trejbal is that there is no provision for the engine to back off the choke, if you open up the throttle before the engine is totally warm. Pay $10 and buy a kit from a reputable parts house.( If you can't get them where you are, let me know, and I'll send you the kit.)An alternative to the DGV/DGAV series is the Weber ADHA vacuum secondary from a Fiat. They are just as tuneable, and don't suffer from the flooding problem, as the secondary barrel will close as engine vacuum drops. As a point of reference, most V8 desrt/rally racing trucks use Holley 4 bbls with vacuum secondaries for exactly the same reason. Total HP is slightly lower, due to the delay in operating the second barrel, but reliability under all conditions is 100%. If a high performance carb keeps flooding out, and the slightly lower performance one does not, which one is actually giving better performance? I'm running the ADHA on my Niva right now, so I can provide all the correct jet sizes, etc. for anyone wishing to install one on a Niva. filter is 1/2 price to buy for Cortina so I guess that makes up for it :-)

Do NOT connect the wires from the Lada computer to either a Weber, or Holley carb. The Weber's/ Holley's require a constant voltage, and the Lada control wire give a cyclical voltage. (on/off/on/off cycle) Lada use this cycle to control fuel flow, rather than using an idle jet/misture screw. Other carbs would run if hooked up to them, but idle mixture would be very poor, as would the Wide open throttle performance. To hook up a weber/holley tap the live wire to the coil, and fit a relay in. when the coil is hot, the relay should run power from the battery, to the idle cut off solenoid. Additionally, if you have an electric choke, and/or fuel pump, they can be run through the same relay. Don't…

The problem with the bowl vents/air bleeds on your carb. is really only half the problem. Yes, on extreme hills fuel can slosh out and run down into the venturi, which will definitely flood the engine. A simple solution is to run the vent all the way up to the top of the air cleaner: anything that sloshes that high will be a problem, no matter what you do. The real problem with the Weber mechanical 2 bbls is that they are basically too big for the Niva engine (too high of a CFM rating). If you are going up a VERY steep hill, using heavy throttle, but a low speed, the mixture can actually flood out the engine. Weber use a power valve to supply additional fuel under low vacuum conditions, such a step hills, and heavy loads. In order to get acceptable on road performance, at higher rpm's, the valve will supply WAY too much fuel when it kicks in during off-road hill climbing. The ADHA vacuum secondary, by comparison, only has a 28mm primary bore, and when vacuum drops the secondary throttle plate will begin to close. These two features put together mean that vacuum in the intake manifold stays at a reasonable level, and fuel from the power valve circuit will atomize correctly, without flooding the engine.By request the jet sizes I'm using on the ADHA primary main fuel jet 125, primary air correction jet 175, secondary main fuel jet 155, secondary air correction jet 195. Primary idle mixture screw is out 2 1/4 turns, secondary idle mixture is out 1 7/8 turns. My carb. is set up using the stock power valve, and has an additional anti stall valve, which is an auxiliary accelerator pump that kicks in under steady throttle, low vacuum conditions. (this valve is designed for an auto transmission, and is to prevent the engine from stalling when you put the tranny into gear. It works equally well to prevent the engine from"

A jeting chart for the Ford and other OEM fitted Webers can be found here

 

Fiat sourced Webers on the Niva

"On a Niva: DATRA(X1/9s and some 128s, and a 1975-6 124s, and maybe some Alfasuds) or a DGV family are common swaps. DATRA are probably the closest bolt ons

The technical columnist for the Lada Owners Club of Canada has this to say: "a weber from a Fiat 1.8 liter engine will also fit. I have one that has a 32 mm primary and secondary bores. It requires a fuel return line to be plumbed back to the tank. " I am not a mechanic so I canno…t

It sounds like the official replacement carb may vary by country: it's probably related to everyone's different emissions laws. The DGA, and DGAV are the two most common replacements here. One point I would like to add to my former note on alternate carbs is to comment that some of the older solexes, with idle enrichment, rather than a choke plate, can make very nice replacements for the Russian 1bbl's. (In Africa, a good example would be the early land rover Solexes for the 2l IOE engines. ) Still another alternative…

In regards to what models/years of Fiat X1/9 carbs will fit Nivas, my experience is based on the Canadian Models. To the best of my knowledge, all of the X1/9 fiats use he same carb footprint, so they should all bolt up to the Niva 2bbl manifolds. I can say positively that the '73 X1/9's with the 1475cc(?) engine use a Weber DATRA model carb that bolts directly on, and has no real emissions gear, but does have the idle cutoff solenoid, and a compatible choke unit. Better still the Lada air filter will bolt in on top. The DATRA has a 32mm primary, a mechanical 32mm secondary, and uses all standard Weber parts, so rebuilds/ re jetting are easy. For anyone seeking the ultimate in intake efficiency, the Fiat 1608cc twin cam (UK spec model only) came with a dual 2bbl down draft intake system. I've never even seen one, but the basic intake bolt pattern is the same so, with some work, they might bolt up to a Niva. The 1608cc Fiat made something like 114 bhp, and 108 ft/lbs, but both figures were at VERY high rpm's, so it might not be worth the effort, unless you're intending to race your Niva. By comparison, the stock, emissions carburetted, 2000cc Fiat's only make 88 bhp ,and 104 ft/lbs , which I'm beating with a modified version of the same carb on my Lada"