FIAT DOHC Engine And Gearbox Installation in a Lada 2101

(Szerző: GorCseW (Ille Balázs), utoljára módosítva: 2007.02.06.)

First of all, I'm in a trouble with writing this howto. I don't want to take it too long, because those who have need each and every step detailed should not start this replacement-thing at all. Who starts it on his own, has enough experience to understand whole processes from one or two words. Although I have to keep my essay informative enough. Therefore I will not go into the details of - for example - hangig the engine on the crane and how to lift it out... these are basic steps. (Article is translated by z.)

What you need

  • Lada 2101...2107 :-) as the recipient car
  • FIAT twin cam engine: 1.6...2.0 from:
    • Fiat 124 Abarth Spider,
    • Fiat 131,
    • Fiat 132,
    • Fiat Argenta,
    • Fiat Regata 100,
    • Lancia Delta,
    • Fiat Ritmo 105, 125, 130TC
  • FIAT 5-speed gearbox with the propeller shaft
  • FIAT gearbox-to-prop.shaft connecting rubber donut
  • 4m flexible fuel hose
  • BOSCH fuel pump
  • fuel filter, specially for being under pressure
  • 5m cable for the battery removal, diameter 10mm
  • cable connector for the new battery cable
  • battery connectors (+ and -)
  • Lada Niva engine mount (it is stronger than the original)
  • propeller shaft joint ("cross" with bearings)
  • water cooler radiator (Polonez or Fiat)
  • electric fan for the given radiator
  • screws, bolts, cables, fuses, etc.
  • accessories for the new engine: starter, alternator, mounting consoles, reservoirs (coolant, windscreen wash, etc),
  • new oil, oil filter, air filter recommended.

The recipient car needs to be prepared for the increased power of the new engine: power brakes (if there is no powerbrake yet), fat tyres (185/60R14 or 195/50R15), suspension modifications (springs, shocks, wishbones, etc).

The engine

A few words on the Fiat DOHC engine we are talking about. This engine was introduced in the Fiat 131 Supermirafiori or in the 124 Special (this was the real debut). The engine type was available in 1.6, 1.8 and 2.0 litre versions. The construction of the engine is the same in all three cases above. (valvetrain, number and size of valves, etc.) The difference is in the pistons and the stroke. While 1.6 engine is bore 84mm / stroke 71.5mm, the 2.0 has the same bore but stroke is 90mm. Of course the 1.8 is made of 84mm bore and 79.2mm stroke. This latter is quite a rare engine.

The cylinder head layout is almost the same on all versions. The only difference which I recognized is the 2.0 has larger intake tunnels - despite the same valve diameters. This difference is only 2mm in diameter. The combustion chamber is the same size and layout. They used different pistons because of the different stroke but same bore. Increasing the compression ratio is solved by humped (i.e. not flat) pistons. In the bigger engine they used flat pistons to reduce compression. Factory default compression ratio is 1:8.9 - 1:9.

Section of the engine

As aligned in a Regata

As aligned in a Strada

There are different pistons available for this engine: original, aftermarket, racing, custom, etc. The British racing pistons require special modifications in the combustion chamber since the much larger "hump" on its top. As a compromise, I increased the compression ratio by using humped pistons instead of flat ones in my 2.0.

Fortunately the ignition did not have to be advanced too much. I think I could not even do it, it seems to be controlled by the computer. I came to this thought after advancing and retarding the distributor - at idling engine - and the engine was idling the same nice speed, no shaking, no stopping. Well this is not the actual topic.

Choosing the engine

This engine was produced in the Abarth line too. This means an oil cooling radiator and increased power. An interesting info is that Lancia had used these engines too, and theirs had 10% much power than the Fiat version with the same displacement. These engines worked in the Lancia Delta and some version of it was fitted into HF Integrale. All engines are bolt compatible (gearbox, mounts, cyl,head, etc). Distributor position and water hoses input and output positions may vary.

Be careful when getting the engine from a front-wheel driven car (Ritmo TC): in this case the distributor position is not OK. In some versions, the distributor was not driven by that wellknown Lada-type T-shaped gear but it is installed on the end of one of the (intake) camshaft. There is no room for it when installing the engine into the Lada. The other version has the distributor on the exhaust camshaft, this one makes no problem. FWD cars' engines have the coolant output which does not end in a T shape over the drivebelt, but it turns back and goes to the cooler radiator besides the cyl.head, betweeen the camshafts. This have to be modified if installing in a RWD car (Lada).

Lada engine removal

In my case the whole thing was isntalled in a 2101 body and I used FIAT Argenta DOHC 2.0 engine with injection system. I tell you this because as far as I know Lada models may vary regarding the room in the engine compartment. (Editor's comment: 2107 has the biggest room of them all)

The installation starts with removing everything from the engine compartment, of course including the engine. You have to remove the battery, the cooling radiator, the coolant reservoir, the horn, the windscreen washer reservoir, ignition electronics (if there is any). After all these you can remove the engine, pracitcally apart from the gearbox. I tried and removed them together, but it was very hard to do. (no room for it at all).

I had to bend the front wall to get the engine+gearbox out

remove the gearbox and the propeller shaft, the clutch fluid reservoir. remove the clutch master cylinder. its hole can be used to get cables thru the firewall bacause you do not need it anymore. I left the powerbrake drum on its original place. Removing is not detailed more.

The gearbox

This type of FIAT gearbox is a wellknown one. It differs from the Lada gearbox. It has a diffenent shape. Body is 90mm longer. It has 5 speeds and a more comfortable gear lever placement. It is bolt-on to the engine. This means that it can be fit on a Lada engine, but the clutch housing size is different, because of the 2.0 litres Fiat engine has a larger flywheel. The starter is on the left instead of the right.

About the propeller shaft

Theoretically propeller shafts and their joints can "cover" up to 15 degrees angle, if the input and output degrees are the same. This is important because the two joints have different accelerations and these are eliminating eachother. Practically this is simply cannot be done, since the rear prop.shaft joint (the "cross") gives you a circular travel when the chassis goes up and down against the suspension. This is caused by the rear axle's cross connection rod (Panhard-rod). You can aim for the same angle mentioned above but never reach it. You have to take care of the front prop.shaft joint (rubber) not to bend too much, this may cause tearing that rubber when using 100% of the available 120BHP (2.0 engine). After taking care of that, you have to follow the rule of thumb of getting the front and rear propellershaft joints at almost the same angle both vertically and horizontally.

Installing the gearbox

You have to fit the gearbox on its place. You may need an assistant for this, I did it alone. Fix it somehow, temporarily. I had to cut the gearbox tunnel in its full length from the seat consoles in a T shape until the cockpit heat radiator. Along this cut I had to bend the sheet metal outwards to enable the gearbox getting into an almost horizontal position. I also had to make room for the propeller shaft joint which was now 90mm closer to the rear.

I had removed the gearswitch lever alltogether with its housing and I fit it to its place. This is the way to measure where to cut the new hole for the stick. It is exactly in the middle, while Lada gearlever is placed to the right (as you already know). This all is worth done when the engine is in its place. Well, to do that, I had to remov the "track bar" (left-to-right steering connection rod), because I had no room connecting the gearbox with the engine. (At this step, cooling radiator and its companion were still on the shelf). Positioning them (engine, gearbox) is much easier with removed steering connection rod.

A very small backdraw of the Fiat gearbox is that the speedometer drive is not the same as the Lada, this way the clock and the counter are cheating. I have 20km's plus after each 100km's! Otherways the Lada speedometer drive cable can be connected without modifications.


I did not work too much on the clutch, I just installed what I got. Otherwise the disc and the assembly remained factory default. Since it is cable operated, the thing works opposite as in Lada. Solving the cable problem is detailed later.


There are two methods for installing it. One: you fit everything and lift it in totally assembled. Two: you lift in the block, and after it is fitted you go on to cylinder head installation, etc.

I cannot tell you which method is the best since I have not tested both ways. The "assembled" way may be better if it won't be fitted with Lada gearbox, because in this case you have to find the place of the engine and the gearbox together. I mean the body has to be modified to find room for the gearbox. If I move the gearbox, the engine will move too. You have to find a position which is OK for the engine (together with its accessories!) and the gearbox too. If you leave the Lada gearbox, it is more simple to install the cylinder block first, and the cylinder head and the intake and exhaust manifolds afterwards. This way you can organize your engine compartment via moving much lighter things! This latter version can be done without real crane, simply with body power :-). This has the backdraw of playing with the camshaft timing settings within the engine compartment!

Well, you have to use Lada engine mount console (on the cylinder block), and it worths to use strong mounts between the console and the crossmember. I have chosen Lada Niva engine mounts. I had only minor problems doing this: I had to drill holes on the console, and I had to use a thick washer on the left side, since the exhaust manifold had no space at the powerbrake vacuum drum. Now I had only a very small room between the drum and the common fuel line.

I also had to deal with the problem of heating. Its metal pipe is bent between the engine and the firewall. Therefore I had to cut the edge where the gearbox tunnel and the firewall is connected, to make room for the pipe end and the flexible hose. This can be seen on the following photo.

Heating hoses

Engine mount

Engine drop-in for the first time

 I admit there were still a few things to cut, because the radiator had no room. The Fiat radiator is a bit taller than the Lada one. You can cut its console and weld it lower, or you can tilt the radiator backwards. I have chosen a Polonez (FSO) radiator instead. I had to remove the original radiator frame till the front wall (sheet); and the radiator had to be tilt onto this surface. Of course I had to cut a hole for the radiator cup. (see photo)

The tilt had to be done to make some room for the fan. I know this is much easier in a 2105 or 2107 (more room!). Bela could do it easily without any cutting in his 2103 too. I could not.

Oil sump and oil pump

Another important thing: the question of the oil sump. If the engine comes from an Argenta, the shape of the sump differs from the usual one. I mean, the Fiat 131 and 132 oil sump resembles to the lada oil sump, but the Argenta sump ends in a T-shaped thing. Better cooling? I don't know. The point is that this T-shape won't fit because of your crossmember. Two arrows show this thing in the following photo.

There are a few solutions for this. You can obtain an other model's oil sump, or you can customize the sump for yourself by cutting and welding. You will need sheet metal, cutting scissors for it and a CO or TIG welder. Replacing the original sump with other model's oil sump you'll have to take care of the ouil pump nozzle. In a case like this, the clearance between the nozzle and the sump bottom will increase, since the T-shaped Argenta oil sump is a bit more shallow than the others. The T-sized has some oil trap around the nozzle, others not. I did the following. I used an 1.6 engine oil pump basket (grille around the nozzle). The 2.0 pump differs from the 1.6 pump at its gears: they are taller. I.e. if the 1.6 has smaller gears, its nozzle is longer. Therefore: nozzle and basket replacement to 1.6 type.

Yes I can offer the Argenta oil pump into Lada too! If you want more oil pressure and a tough oil pump, just fit it. Everything is the same (bolt-on!) as in the Lada engine. Only the driven gear's shaft has to be replaced to a lada shaft. Well as far as I'm right this is not made of one piece, it is just pushed together. You just may have to disassemble this (under heat? don't know) and put together with a Lada oil pump shaft.

Other bits

If you still have the factory original dust/water/moisture shield around the engine, bolt to the front wall and the crossmember, you can remove and throw it away, or cut hole in it for the oil filter. It is not located at the same place as on the Lada engine. I hope you all guessed this if you're at this stage of the transplantation.

The air volume sensor and the airbox is to the right from the engine. The air volume sensor console is used at my project. I welded 3 members on it, and I bolt it to the battery console and the inner wing. On this console (the sensor's one) is the water coolant reservoir placed, thus it is removed from left to right. Its original place is now occupied by the Digiplex ignition circuitry. On the left is the 2105-type windscreen washer reservoir placed.

The original airbox did not have room in the engine compartment, so that I had to find an other solution for that. This is a Barkas-type, which is a well-known van in the Eastern-EU region. It is interesting that the original airbox did have enough room in Bela's 2103.

Assembling the propeller shaft

There are 2 ways, again. Firstly, the original setup is done, when you use the Fiat gearbox. This gearbox is ~90mm longer than the original, above other differences in shape. Now your original Lada propeller shaft wont fit! Yhave to use the front part of the Argenta propeller shaft. Its propeller shaft is divided into sections differently than Lada. Surprisingly, you can combine these parts to fit exactly between the newly implanted Fiat engine+gearbox and the Lada differential. You just have to dismantle them (Lada, Fiat), then replace the Lada front part with the Fiat front part, and assemble them with a new (!) joint.

Surprisingly, all dimensions are the same. Only the bearing (with rubber bed) has to be replaced. At this step take care of the mounting console, since it is asymetric. Also take care of greasing the joints which you push together. British joint cross has a greasing knob, others not.

Fiat front, Lada rear

greasing knob

The other way to solve propeller shaft length problem: if you cannot obtain an Argenta prop.shaft. In this case you have to cut and weld the Lada propeller shaft's front part. To do that, you have to take it to a workshop where they can do precise job. I would not trust in such a thing.

Electricity: this part was a real problem for me. I dropped the Lada alternator, and replaced it with the Magneti Marelli alternator. Now this thing is totally different from the Russian one. This has internal induction. It has only one input from the battery, and it is ready to work. The charge/discharge feedback lamp was the most difficult thing to get to work. You have to do it like this: the lamp has a "15" wire from somewhere, and the GND has to be connected to the only one connector seen on the alternator. If the engine stalls, the lamp is lit. If the engine starts and the alternator is charging, there is no current, therefore no light. If the battery voltage is (even slightly only) larger than the alternator's voltage, the lamp lights. This warns you a failed alternator or an accidental loss of induction within. To connect it like that, you have to modify the connections of this lamp within the dashboard.

The sensors in the engine compartment cannot make you a problem. They just (almost) cannot put together in a wrong way. Unfortunately I did not note everything when took out the engine from the Argenta. I found 3 connectors at the computer, and did not know what they are. Of course there is a manual, but it costs a lot. I found it too much to pay for only one circuit diagram. When you start the engine it gets a signal on one wire. There is the ignition (15) too. There goes the electrical fuel pump power supply. Despite the BOSCH system is in the other corner of the engine compartment, and the pump in the back of the car.

I have to mention that many types of ignition systems are available. I use the DigiPLEX electronics with L-Jetronic ignition system. This (LJ) system also came with HALL sensor ignition. Not to mention the carburettor version where they used simple ignition points. These are the most easy to get to work. At the DigiPLEX ignition you have to be aware of the sensor of the pistons upmost position (TDC, Top Dead Centre), on the crankshaft. The flywheel has to be factory default, since the ignition electronics get the RPM data from this cogwheel. You may have fuel volume problems. What is important here: the DigiPLEX and the L-Jet system can be taken apart. The DigiPLEX also works with dual twin-webers (DCOE40 or DCOE45).

Battery had to be moved to the trunk, above the rear axle. Voltage is taken into the front of the car via a welding-cable, within the cockpit. It is taken through the hole left by the clutch master cylinder. Here the + cable is connected to the BOSCH controller's switch, the starter, the alternator and other relays.

Exhaust: well, yes. Unfortunately the original exhaust manifold has a different angle than the original one. As far as I examined it, the Y-pipe connection is the same, but its angle differs. That's enough to be a problem. Of course the Y pipe connection may be very different depending on the donor car's engine layout (FWD or RWD). Thus I had to create a "customized" exhaust, which was welded together of 7 or more pieces originating from a Lada and a Fiat Y-pipe. Now it was connected to the original Lada exhaust (factory default 40mm max diameter). My first thing to do was to take it to an exhaust specialist and order a professional Y-pipe along with a 60mm sports exhaust system. The difference is noticable! Not only the sound but the power! Anyways, a sports system worths it!

Clutch. Argenta clutch is cable-controlled. I did not experience with Fiat gearbox and fluid-operated clutch.. it was more simple to convert the clutch pedal to operate the cable. I just drilled a hole in the firewall, inserted the cable housing, and converting the clutch pedal to a "scales-type" which means that it has to have a piece of metal welded on the opposite side of its turning point (shaft). I had only an 80mm room for this arm, and I had to weld only twice. I also had to weld a spacer because the cable was too long and I did not want to modify the factory (Argenta) cable. It has a threaded end for adjusting on its end at the gearbox. On its other end it has an O-ring, this can be fastened to our newly welded arm on the clutch pedal via a M8 bolt. This is why the spacer needed: it would be hard to shorten this cable - while keeping its original function.

Throttle cable: it remained intact too. I just pulled it into the cockpit via the former hole of the clutch master cylinder, I turned it in a U-shape under the steering column and I made a small console for it which was fastened under two of the steering column's bolts. The cable ending was applied on the throttle pedal. This way I can adjust the pedal travel from min to max throttle.

not too neat, is it? :-)

You have to sort out a fuel back line.. This means that at the original in/out connections you have to isntall the pump and the filter. The filter is under pressure, it is placed after the pump. I used a 7mm (internal diameter) fuel hose. I used Argenta's original metallic pipe at the injector connections, since it is a special one with threads. This is an 50mm long part only. Between the filter and the injector I used high pressure hoses (4Q). The original Lada fuel pipe is the back pipe. There are 2 ways (again) to create these 2 ways of fuel on the fuel tank.
1. First solution is to connect the feedback line in the breater pipe via a T-pipe.
2. The other way is to take out the fuel level sensor's panel, and drill hole on it, and weld/ solder a (copper) connecting pipe in it. This way you can lead your feedback pipe to the bottom of the tank, avoiding disgusting sounds :-) Take care! Serious danger of detonation when working on even an empty fuel tank! - anyways, this latter one is much more nice.

Injector's computer (ECU) is in the glovebox. The fuel pump got a fuse. The radiator's fan is switched on/off manually. I inserted a relay in the starter engine line (not the mains but the switching line). After all, I have to give some fashion for it: I mean the gearbox tunnel cuttings and the engine compartment. It is not too neat currently either.

Final engine bay photos:

Experiences: terrific torque! on wet tarmac, the 165mm wide tyres spin immediately even in third gear! (I don't use the 185/60R14's in winter). Fuel consumption is 10..15litres pro 100km's while I am not that old man type driver. I did not test the highest speed, but it accelerates quite tough in 5th speed at 120km/h. I tested my speedometer cheat by using a GPS. Going at 133km/h it shos 160km/h. Such an engine swap needs an LSD (limited slip differnetial) immediately! The gearbox ratios seem to be too short. I have a 1:4.1 differential, Argenta's came with 1:3.9 or 1:3.73.