940T (auto) Motor into 81 240 (manual)

Fairly easy, well not really, its a project. Even the new front exhaust pipe routing and customisation takes unexpected effort, fitting of an oxygen sensor etc.
Clutch is a weak link area for future attention, but hopefully ok for a while on std boost if in A1 cond.
The ignition distributor signal and flywheel tooth count side of things this will slow you down unless you have already obtained a flywheel with 58 holes on 60 pattern and new wiring required as your 81 wont have a flywheel position sensor etc, nor the bellhousing cutout for sensor. The front mounted distributor, either a hall sensor or someting from Yoshifab etc, is also a new project as you can't use the rear ign distributor. Least your model has the spiral gear on the intermediate shaft. Intercooling piping also need adaptation creativity.
Then the fuel system needs pump changes as your moving from mechanical injection to EFI.
And numerous other tasks to work through, but many people have completed the conversion given time to do it properly.

have a look at a wasted spark conversion. you will still need the flywheel though dustributor no longer required.

_Do i need to relocate the distributor to the front of the motor?_

Yes. Unless you go with a wasted spark ignition system.

_What custom wiring do i need to do?_

Plenty. Fitting a new Dave Barton LH2.4 harness instead of a ratty old used NA harness a good start. You'll also need to sort out where you're gonna get your vehicle speed signal (from late model diff sender, or Brantz BR-4 on the speedo cable) and wire that, too.

_Will the existing clutch setup from my 81 240 work?_

Clutch? Maybe. Flywheel? No - you will need a flywheel with the LH 2.4 60 tooth minus 2 pattern for the RPM sensor.

_Anything else i have missed?_ 

Yes. Plenty.

• You will need to supply a VSS to the LH2.4 ECU or the thing will never idle properly and drink fuel like there's no tomorrow.
• You will need to change the fuel pump over from a 5 Bar K-Jet pump to a 3 Bar LH pump.
• You will need to turn the collapsible steering joint upside down so you can get the exhaust to exit without interference.
• etc

As far as im aware it should be a fairly… straight forward swap

Into a K-Jet car? Not really.

It’s straightforward compared to fitting, I dunno, a Lexus V8 for example.
There’re just a lot of little gotchas you need to address.

Surely the 940 drives better than the 240.

A few posters brought up the thought of keeping the 940T going and developing it. This is a valid consideration. As I have both (non turbo on 940) I will comment.
The 244 is lighter and arguably looks better, but…

In the 940’s positives:
The 940 rwd has the best steering Volvo ever made.
It has ABS brakes, safer by far, the most comfortable seats, the quietest interior, no body flex, easy to do maintenance on, superior ride on trips. Engine bay has room for all mods, including a 16v head etc. Room for bigger wheels. Airbag might work (or not). Good heating and cooling. And can be manualised.
Far heavier than a 240 though.

Having driven both, the 940 dumps all over the 240. 240 suspension is designed in the 1970s and it shows. Luxobarge all the way and mod it over time. Also, having done a k-jet to 2.2 mod, it can be a PITA. I'd expect the 2.4 mod to be worse. On top of this, if your M46 doesn't have the turbo cluches, you're setting yourself up for a new OD unit and probably 3rd gear in the near future. At least the 940 will take a multitude of different gearbox options.

Roinik if your M46 doesn't have the turbo cluches, you're setting yourself up for a new OD unit and probably 3rd gear in the near future.

Were there many changes made to the J-type overdrive for turbo-engined cars? (IIRC the later turbos went from J-types to J/P types and then P types, but then again the J-types sat in B30E 164Es that had M410 boxes).

Truth be told, the 740/940 suspension was also designed in the 1970s too.

Having owned and driven several 240s, 740s, and 940s - IMHO, the 240 is more solidly built, IMHO; plenty of metal where the 7/9s used plastic. The 940s are quieter and better built than the 740s; 940 has some ease of maintenance advantages over the 240s. Lots more sound deadening in the 940s than 240s which adds to weight, but makes the 9 nicer to drive long distance.

Preferred daily? The 940, but the 240 is still miles in front of any Korean rental turd I've been forced to endure. With that in mind (and I may be wrong about this) intact 940s, especially turbos, may appreciate in value as they become harder to find - the number that came to OZ wasn't that huge.

SINGV240T - What's your objective with the 1981 240 wagon build - a bit more go, or a lot more go?

I wouldn’t worry about the internal strength of that B230FT … you mention “rods”, which is why I say this. Properly tuned so there’s not overwhelming pinging, the standard rods should be fine, even with embiggened boost.

Fuel pump you mentioned as a potential future change; IMHO make sure you’re running an EFI (not K-Jet) main/pressure pump in the first instance.

K-Jet to 2.4 is almost the same as 2.2.

The main issue you will face is the wiring harness. You can start with a 940 one and hack it up, but if you wanted a super clean install, you'd want to get the firewall plates and LH-2.4 loom from a later 240 that came with 2.4 from the factory.

You can use the same clutch but you will need a flywheel with notches for the crank trigger (or you can get your flywheel modified to add the notches). You will also need to notch the bellhousing so there's space for the crank trigger bracket. You can do this by hand with an angle grinder, it's not a precision fit. Probably will be much easier with the gearbox out of the car though.

The K-Jet fuel system you can run as-is, it will handle as much fuel as the stock 940T system.

@"jamesinc" writes: <The K-Jet fuel system you can run as-is, it will handle as much fuel as the stock 940T system.>

Hmm, if your refering to the K-Jet 'fuel pump' system and its much higher pressure, well maybe but...

I think the EFI fuel pressure regulator will get a hard time regulating pressure down (K 75 - EFI 50= -25psi) for EFI injectors, but for a turbo with boost pressure rising and falling all the time the FPR will struggle. Also the turbo engine requires a higher fuel flow rate, (K-Jet is higher 'pressure' based with lower flow, than a turbo system).
For example, a small K-Jet era 'in-tank pump' does not supply enough fuel volume to the main pump then to the engine EFI injectors at mid boost levels upwards.
This is a fact (unless in-tank has been upgraded) and the resultant is a lean AFR, with symptoms, gee at 4,000 rpm the engine just doesn't want to rev anymore,,, a hesitant off-on situation. (Guys if at any point your feeling what I'm saying back off and arrange for bigger pumps and fit an AFR - airflow ratio meter well after the turbocharger).

@SINGV240T - Good news is the source components required are on the 940T.