Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - Is a new 4.0/4.6 interchangeable w/old 3.5L?

Is a new Rover 4.0 or 4.6 (current Discovery and Range Rover motors, I believe) interchangeable with an old 3.5? I put one into my B years ago, and it's getting near rebuild time. I'd like to move up to something hotter and fuel injected, though, if possible. I just have your basic SD1 5-speed box. I was thinking of just trying to buy a totalled Discovery or Rangie, and salvaging the motor and EFI setup.

I realize that the 4.0 differs from the 3.5/3.9/4.2 etc. in that the bearing shells are cross-bolted. Nothin' wrong with that. But something tells me there might be differences which preclude swapping it for a good old 3.5. Please advise.

I changed my buick 215 for a rover 4.6L. I don't know if the buick 215 is exactly identical to early rover 3.5L.
The major differences that affected my conversion were:
1) the rear flange end of crankshaft, where the tranny input shaft goes into the pilot bushing, was longer.
- I simply cut off the excess from the crank.
2)pilot bushing was different size
- I found one with the correct inside diameter and had outside diameter turned down to correct size.
3) threaded holes on head for accessory mounting was a smaller diameter.
- tapped and threaded hole to allow mounting of alt. bracket.

That's all I can remember right now. If there were any others, it must not have been a big deal to sort out.

Also, If you are going from a V-belt drive system, the newer engines use a serpentine belt and you might have to check for clearance issues depending on your setup.
If you're going to the latest 4.6, it uses a Direct Ignition system and you can't use a distributor, not a big deal If you plan on transferring everything over. I'm not sure if any of the engine sensors get in the way of anything. You might have to machine the plenum in order to fit under the hood. If you're new to fuel injection, you must use all required sensors for optimum performace, which means at least addition of oxygen sensor in your exhaust. You'll also have to adapt the fuel pump and lines to your tank. I'm sure others will give more specific and detailed info. Good luck.

Does anyone have a list of american cars that have
the alum. 215 or other engines that will fit in a MGA.

Joaquin, seems a pretty comprehensive reply to me.

Roger Parker

yes the 4.0/4.6 is a drop in replacement for the 3.5,
there is no modifications to make at all.the rimmer 6.0 ltre will drop in allso but the manifold might be to high, 500 hp +.

This thread was discussed between 18/11/2000 and 02/12/2000

MG MGB GT V8 Factory Originals Technical index

This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.