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 - v8 engine

Does anyone know of a good 3.5V8 engine for sale? The one in my car is buring and dripping a good deal of oil and I can feel a change coming on...
T Green

Do it the easy way, buy a new short 3.9. I looked at the cost of refurbishing an old 3.5 and I could have saved maybe 25% (if I was lucky). Plus the 3.9 is a much more stronger/reliable/ powerful block.

I may be breaking my midget V8 and there's a good engine in there. See the "No-one wants to buy my V8" Thread on the Midget General board.
You may have to wait a week as I'm trying to sell the car complete (it's not likely to sell tho')
Stuart Robson

Interesting responses. I am worried about the 3.9 because it was never a standard MG fitment to the MGB. WOuld that not mean it would become a "special" and as such attract nasty insurance problems? Same goes for fitting EFI?
T Green

I have an original MGGTV8 block waiting for a rebore in Hampshire. If you decide to rebuild, it's yours for a very small consideration.


I had no problems at all based on
the fact that the RV8 had the 3.9. Escentially it's the same engine, just bored out and lots of extra reinforing/thicker gussets etc. Ask your insurer.
Stick with the existing manifold (and bits)if you want.Everything just bolts on.

Re insurance, I have an MGB 3.9 Roadster (very "non standard") and I am insured with Footman James, fully comp on a classic policy. They know everything about the car and there quotes are very competative!
R Weston

Re Insurance - same experience with Footman James.

The non-cross bolted Rover V8s have a serious problem with main bearing cap stability. Whilst it has been suggested that a stud kit can help cure this, I would suggest that you go for a 4.6 litre cross bolted block which will cost little if anything more.

Seek advice, and prices from experts such as:-

John Eales:-


and Chris Betson:-

I currently have a John Eales 3.9 litre engine, but were I to have another I'd be tempted to go to 5.3 litres, but still run on SUs so it looks standard!
Nigel Steward

The 3.5's certaily do have problems. I looked at at the least half a dozen rebuild candidates and every one of them had one or two tiny cracks around the main bearing cap bolts. Apparently the bolts work a little loose (overheating?) and the crank moves a little(not good).
If you take the sump off you will often see them either side. Initialy I did buy a 3.5 & I got the block crack tested and it turned out there were cracks all through, not just the ones I could see.
The local cure is to put supa thread locker on the bolts and glue them up tight. This seems to work. Studs are viewed as too expensive. In contrast the 3.9 bearing caps are solid square chunks of steel that site closely and squarely right down into the block. Or rather, the block comes right up around them. On the cross bolted versions they stroked the 3.9 to 4.6 which added more stresses; so bolts were also screwed through from the outside into the caps from the side.
Don't get me wrong, relative to other engines of the period the rover 3.5 motors are very good. It's just that the 3.9 block is the end product of about 35 years of production. It was the big final fix.

This thread was discussed between 04/04/2006 and 06/04/2006

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.