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MG MGB GT V8 Factory Originals Technical - Info on V8 conversion???

I have a late model mgb (77 model, chassis 420xxx) with a dead 1800 engine and want to go down the v8 route. Looking at a 302 Ford or Holden/Chev simply cause they are easily and cheaply available in Australia, whereas the 3.5/3.9 Rover seem to be expensive and hard to source.
Does anyone know where I can get info regarding this swap, or indeed supply me with their insight to this swap?


Take a look at There is a lot of information there. This bulletin board's archives is also helpful. A multitude of books such as "How to give your MGB V8 power" will also guide you in the right direction.

Good luck and keep in touch!

rick ingram


I am working on a V8 conversion using a Rover 3.5 engine. The engine is from an 86 Range Rover and cost $1000 dollars complete with computer, loom and all engine accessories. A bell housing, throw out lever and clutch plate to suit a Ford Falcon T5 5 speed transmission is available from Dellow automotive in Sydney.

The main advantages of using the Rover engine is that it is no heavier than the 1800 CI engine and as the factory produced mgb v8 used this engine many other conversion parts are readily available.

Good luck


Gidday Brian,
You sound like a local person to know!
After making various phone calls today it has become apparent that although the Ford is available 'everywhere', the Rover is the easier conversion.....and thus might actually save me $$ in the overall cost.
Can I ask you please Brian, where did you source the engine or do you have any good contacts with wreckers/parts suppliers? Are you completing the work yourself?
Cheers mate.

You're right, 3.9s are hard to get because all the people with 3.5's in their range rovers want them because they are a much better motor than the 3.5 (in standard trim that is, you can get 200BHP from a 3.5 if you spend a bit).
Also if I was going to use other engines I'd be looking at a Lexus V8.
What ever you do go and see an engineer before you spend money, you will have to get a certificate to register the car anyway, so you'll not be wasting any money. You may not be allowed to use other engines, at least not without enduring allot more expensive beaurocratic nonsence. The rover engine swap is an "official" MG using "MG components". Also unless you've got pots of money and don't care, the Rover "official" engine swap has way higher resale value if you ever need to realize an asset.
I found a low km 3.9 with all the gear for $2200, but had to spend a long time looking. I think now it would have been better to get a new short 3.9 and hunt around for the other bits.
You can get a new short high comp' 3.9 for around $3000 (a place in Adelaide, Triumph and Rover spares). Keep in mind the heads on the 3.9 and the 3.5 are interchangable so are readly available and not very expensive. Also you may be wanting to get ported and flowed heads anyway. The intake manifolds etc on the 3.5 are also the same as the 3.9, although different sensors/computer. You also need to use the front off a 3.5 as the 3.9 has a different oil pump which does not let you use the MGV8 oil pump adapter.

I'm using a Toyota supra box with a a bell housing from Dellow. The Toyota box is strong, light and compact enought to fit into the MG transmission tunnel without any alterations being made.I also got the box from Dellow ($650) so I could choose the gear ratios but could have got it for around $300 at a wrecker if I wasn't too fussed about ratios. Also you need to get the 21inch version of the box. The boxes are all the same lenght but they comes in four gearlever extension housing lenghts, we want the longest, "D" variety. Don't buy Dellos 0.75 inch supra slave cylinder, no good for MG's. He might still do the 1 and 1/16th set up, you need to ask. I'm used a one inch range rover slave after I threw away the supra slave. You can't use the Rangerover manual flywheel and clutch, too big. You can find a Rover one, or have half an inch machined off the thickness of the Range rover flywheel and redrill for Dellows clutch. .
Sometimes you'll see a Dellow gearbox and adaptor for sale from a Rover or P76 second hand, but you need to be lucky.
If you really wish to save money then the old Leyland P76 is your best bet. There was even a manual gearbox variety (3 forward gears only though). They are very similiar to Rover motors and many parts (heads, front covers, valley manifolds etc) are interchangeable. The motors are a 4.4 (I think) and are about half an inch taller than the Rover block with a longer throw crank. They develope more power than the 3.5 rovers but the block is not as stiff I'm told. The extra height is not really a problem (as I had initially thought) because in my car I still have half an inch bonnet clearance. Actually I've often though that mounting the engine done on the front crossmember rather than the rails would be a heaps better way to go, I estimate that you would get the engine to site futher down at least 1.5 inches. A guy in America has done this very successfully, perhaps he's reading this thread and can tell you about it.
If you are looking at 3.5's inspect the block around the main bearing clamps (you'll need to take the sump off) closely. The bearing bolts tend to work loose and then the crank moves a little and fine cracks develope in the block around them and spread. My 3.5 front and water pump came from a dud 3.5.. If you get a good one I'm told the practice is to either replace the bolts with studs , or use super stud locker on the bolts and do them up tight.
Unless you're very talented and patient exhaust manifolds are another big inducement to stay Rover (or P76). They are hard to make I judge. You can get through the guards/RV8 style exhaust manifolds from a variety of places,AAA automotive in Adelaide sell the nicest set of two inch mandrell bent headers I've ever seen for $1200 in mild steel, Clive Weatly will sell you a RV8 copy in stainless steel for around 400 punds (I got these), there's a guy in northern victoria who'll sell you his verion in mild steel for around $800.
Roger Williams books "How to give you MG V8 power" and "How to improve your MGB, MGC or MGV8" are both very good though I prefer the second one. He's got a new one out soon and sometimes posts here. When, Roger when, we're all waiting!

Forgot to mention, something to be wary of with P76's is that the fly wheel is not interchangable with Rovers and so manual flywheels are hard to get and expensive I believe

Thanks guys.
Hi Peter......yes the Lexus V8 interests me greatly. I have a friend who put one in his MX5 and it is ridiculously fast but also very smooth. I like it alot! Having mucked with my GT Subaru Forester (that runs flat 13sec quarters), I have built up some great friends for Jap parts. These engines are also very plentful and I can get them at 'mates rates' through my Jap sources. But I know absolutely nothing about this conversion or even if it will fit easily. Love to get one though!
The 'engineer's certificate' can be done for a cold carton also through mates. No problems there whatsoever. The dollars arent that much of an issue either. Well, a point!
Your info is wonderful. I have found out so much in the past few days. I will continue to 'dig' for info and see which path is the best to follow.

G,day Dave

I picked up the engine through the Trading Post. The guy took it out of the rangie and fitted an Izuzu diesel. I would recommend you buy a complete set up if you can. Buying bits and pieces like flywheels, starter motors, heads and engine management bits can soon add up to a lot of money.

Actually, the later model Rover engines with what is known as the Hot Wire air flow sensor is a better option than the earlier one that I am using. I'm not sure of the exact year of introduction in Australia but it is around early nineties. Of course if you prefer a carburettor you should be looking at earlier engines.

I considered a Lexus however could not find any info regarding conversion so you would need to be prepared for some problem solving and trial and error.

I haven't actually started stripping the B yet but will be soon. I have just completed building a roll-over jig (rotisserie)for the vehicle. Yes I will be doing most of the work myself.


Try this link

"When, Roger when, we're all waiting!"

I just spoke to Roger (via e-mail), and received a flyer for the third edition from his publisher yesterday. I printed a bunch of copies of it and will be handing them out at the V8 meet in Terre Haute next week. The third edition will be out this fall. I have read the draft, and it will be worth the wait.
Dan Masters

Also- starter motor needs to be off an SD1 rover, it has the soliniod on the bottom. The Range rover one won't fit (solinoid on the side), by about 0.4 cm ONLY, which is frustrating. It would be a good idea to use the harmonic balancer off an SD1, this has a long neck and locates the steering rack under it very neatly.

This thread was discussed between 01/06/2005 and 05/06/2005

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