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MG MGB GT V8 Factory Originals Technical - Tips on buying a Rover V8

I am beginning restoration of a '64 B. I have managed to pick up a replacement heritage shell cheaply also. Reading various info on the web incl this site I am seriously considering going one step further and rebuilding as a V8.

Not knowing much about possible weaknesses with the rover motor, would anyone be able to pass some hints on things (+ve or -ve) to look out for looking for an engine. For example I have read on a rover restoration website of an engine block that was discarded due to advanced corrosion - not picked up until the liners were pressed out. Obviously I would prefer not to waste money on a throwaway if at all possible!


Email me if you like I have converted my 1964 to V8.


Ian Buckley

Ian will get you going - I would be leary about any engine that I had not heard running.

The results of a good Rover conversion are very worthwhile.

Hi Dom,
I think I may have met you at the wesley college concourse a couple of years back, hanging around the V8 section?.
Keep away from 3.5's unless you know the motor inside out. They're attractive because they are way cheaper than 3.9's, for a reason. The main bearing cap bolts can (and often) work a little loose and then the block will crack around those bolts. The cracks can propogate. I orrigionaly bought a 3.5 with the intention of a quick rebuild. There were some fine cracks either side of the bolts, which turned out to be very widespread. It was going to cost a little over three grand to weld, bore out to 3.9 and refurbish ie not worth it. At that time you could get new 3.9 short motors from triumph and rover spares in Adelaide for $2990. Ian can tell you more about them.
There after I looked at about half a dozen of 3.5's (I insisted on the seller removing the sump so I could inspect) or supposedly blocks in "good "condition, they all had cracks. Eventually I found a very low Km 3.9 for $2300 with all the Hot wire gear. It was the first 3.9 I looked at, and it was just fine.
The 3.9 is a much stronger block than the 3.5 and reinforced around the bearings.
My 3.9 (a'94 motor) had the serpentine belt front cover on it, which will make it difficult to fit in the MG. The easiest solution was to fit the '80's front cover (which allows you to fit the oil pump base), which just bolted right on.
There's a very good book availiable at the technical book shop in Elizabeth street Melb city. "How to improve your MGB, MGC or MGV8" by Roger Williams. He's also written "How to convert your MG to V8 Power". Personally I like first mentioned book more.

In summary- Look for a 3.9 Hot wire EFI. Buy a reco' or second hand '80s front cover, which will cost you less than the oil pump adaptor. I suggest a Dellow supra conversion bell housing and supra box from Sydney.
Unless you intend on making your own, as I did, I suggest you get your engine brackets from Glenn Towery in the US. He makes his to set the engine further back and lower than standard, which really suits the shorter supra gearbox.
Race radiators in Dandenong, make a Alloy MGB V8 radiator, which will ensure you never have overheating problems, expensive but worth it I think.
You're welcome to look at my conversion if you like, however mine is a '75 car and a little diferent to yours. I live near St.Kilda.
PS You just won't believe how well a V8 conversion works in the MGB. Not only do you get two to three times the power and torque but the car gets a little lighter, and the handleing actually improves, magic!
The value of the car also increases alot, not that you'll ever want to sell it!

Dom, I have a list of all the Rover V8 specs and engine numbers, if you e-mail me I will send it back to you. I'm not sure about the cracking around the mains bolts but I've heard of engines with the mains caps moving if subjected to high rpm.If you rebuild an engine it is advisable to convert to an "ARP" mains stud kit which prevents this happening.Late 3.5 and 3.9 blocks are stronger and have thicker webbing in important areas.
Hope this is of assistance.

K.R Jackson

Many thanks gentlemen.
Sounds like the late 3.5 or 3.9 is the way to go to avoid cracked blocks.
Peter and Ian, If its OK with you both I might take up your respective offers and contact you further by email.
Peter, I went to this year's concourse (and had a good look around the V8 section) but this was the 1st time I attended it at Wesley. If I were to proceed with a V8 conversion it could be similar to yours after all as I am rebuilding the car using a rubber bumper heritage shell (planning on transferring parts across from my '64 shell - having just completed the front chrome bumper conversion already).
Thanks again


Triumph Rover Spares still have a couple of 3.9v8 for sale
i think they are new ( ring up and find out )
and since your in melbourne
it is a must that you go to MG Workshops in east bentleigh
they converted my 64b a few years back now to a 3.5v8 with all the fruit ( eg fully balanced and blueprinted motor, 5 speed supra box and 4 piston calipers brakes up front )

having said all that id still prefer a 3.9 but they are scarce, the fuel injection is a choice between the federal or the vitesse type system
The federal is more common and cheaper but the vitesse is better and more $$$ but ive seen mods where you can expose the 8 air trumpets ( looks like a Ford GT40 kit ) very nice

Dom certainly you may, sounds like you're going to have a very nice conversion at the end of it.
I was at wesly this year, mine was the demask red V8 chrome conversion. Happy to provide any useful details you did'nt already get. Steves right about the guys at MG workshops, they are particularly helpful. Andrew runs the place and daren is very knowledgeable about MG's. They seem to have one of everything to do with MG's in that place. The shop prices are usually OK, sometimes good.
I got them to do a roadworthy prior to taking the car to the the engineer.
Give them a call, if they have a V8 in progress they will probably suggest you come and have a look.
If you haven't already got one, Collin at enkleman engineers in Moorabbin is the Guy who does all MG workshops V8's. It might be worth giving him a call to oviod suprises. For example I learned that you need approximatly 1cm clearance around engine and gearbox after I had installed.

HI strange about the rover blocks cracking have six and not one is cracked. the so called fat block 3.5 and the older one's. the fat block has a lot more alloy in the block to make it stronger. you have to watch for blown head gasket's a common problem, if you don't use anti-freeze you will get corrosion,
the camshaft wears on normal rovers the outer row of headbolts should not be used or screwed in at 20 ftlbs

hi forgot to say see web site for more info on the 3/5.

If I had it all to do over right from the start I'd go FORD!
Michael S. Domanowski

Although the 3.9 is a much better motor, supposed to be the ideal for MGB's, there is a significant advantage in using a good 3.5. Brakes. if you use a 3.9 then you need to upgrade the brakes, you can get a Kit from MG workshops that consists of volvo calipers, stainless adaptor hoses and nissan ventilated disks plus spacer. (Or you could something together you self.)
If you use a 3.5 then you can get away with fitting MG GTV8 brakes, which is a solid and slightly thicker disk and slightly wider calipers, for about half the cost.


One of best sites for Rover V8 info, and you can buy a new engine for price of rebuild, the pop up gives a reasonable price to US but they ship worldwide.

The trend is for larger capacities and a 5.0l with wildcat heads will up the bhp.

The 3.9 has better airflow than 3.5 and will rev freely but cannot supply the huge torque of larger capacities.

Not sure how the brake position pans out with your rules.


its still fairly pricey when you convert it to aussie dollars and then include the shipping costs.
Granted 4.0 and 4.6 engines look the goods
( are they a simple install into a B comparing to the older 3.5 and 3.9's ? )
I think for most applications considering dollars a nicely warmed over 3.9 will suffice for fast road use , especially in Oz where the govt seem bent on revenue raising ( speed cameras )


I tried to ask the same question a couple of weeks ago. If anyone can help explain the differences needed to install a 4.0 or 4.6 vs the 3.5, 3.9 or 4.2 in an early chrome bumper car I'd appreciate it. I's like to think it might be possible to do any preparation to the car before i finish fitting the 3.5, so that I can do a swap to a bigger motor with minimal headaches later on. Any help?


I changed to 4.6 from 3.5 a number of years ago, was a CB GT but now Heritage shell roadster.

The only change I can recollect was a change to RV8 clutch with SD1 box and steady bar, knackered the halfshafts but these were non B, and added Quaife LSD, and Wilwood vented discs and calipers. The 4.6 does generate more heat so changed to Ali rad and RV8 Manifolds more recently.


Externally, there's no difference between a 3.5 and a 4.6 You can't really tell by looking at the outside of the block. It's the insides that count! The only differences 'should' be the exhaust headers will be bigger with the 4.6 and the radiator needs to be very large, and maybe add an oil cooler, but some will argue that one.

In 3 words: Exhaust Header Holes


Thanks for the feedback. The current plan is RV8 headers, jet hot treatment, V8 radiator and a 19 row oil cooler.

But I think I hear you. Keep it cool.


My mistake that book shop is in Swanston st, up near the museum, phne them first I suggest.That "How to improve.." book has an entire chapter on the multiple versions of the Rover V8, their pros & cons. You don't want to get a early '80's Range Rover motor, they were around 100BHP

Pete, you'll need a heaver clutch, and maybe a survo to assist, either that or spend time in the gym growing powerful leg muscles. (MG Man! Able to leap tall buildings with a single bound!)


Thanks, I know the tech bookshop well. I have also seen the book you refer to at the auto book shop (not sure of exact name) at the top end of Burke Road, Camberwell.

I have tried emailing you direct (mobilexxon address) but the email bounced back.


The exxon and mobil might have been transposed, my mistake.Try this version
However I'm off the next few days so won't be here.

I'd be interested to see an actual heritage body shell, a bit like the holy grail really. It amazes me that you can still buy what is essentially a new MGB 24 years after they (evil BL) stopped them making them.

Yeah I know the shop, the motor book shop or something like, small crowded place, specializes in magazines/books about cars. I bought a Haynes '93 range rover/discovery manual there which wasn't much use.The wiring diagrams were bizzare (Block diagams done on windows it seems, and not relevant to Australia) and every second paragraph seemed to be "take it to a Range Rover specialist". Not the proprietors fault though.
Even if you don't go the V8 path Rogers "How to improve.." book is a very interesting read. I'd suggest you still phone around though, the price seems to vary from $18 to $60 for unkown reasons.

This thread was discussed between 01/05/2004 and 17/05/2004

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