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MG MGB GT V8 Factory Originals Technical - V8 conversion in Australia

Hello fellow forumites
i currently own a 79gt which im thinking of doing a v8 conversion on ( or maybe supercharged 4 not sure )
ive bought the book how to give you mgb v8 power and read it a few times
however i would like to know the simplest way to go v8

i was thinking of doing the following
get an 3.5litre SD1 motor, recondition it.
add offenhauser manifold,
holley390 or edelbrock 500 carb,
rv8 exhaust
supra g/box with bellhousing from dellow
what diff can i use ?
do i need to make a cutom yoke assembly?

now can i buy the remote oil filter kit, engine mounts and engine steady bar from overseas and will they still fit ?


Steve in Oz

Talk to Adrian Akhurst at:-
AA automotive :-
14 Nightingale Av
Magill SA 08 8364 4988
He sells conversion parts.

You can use the standard diff. with a Supra or Celica G'box
I don't know what you mean by a custom yoke
Barrie E
Barrie Egerton

Hi Steve,
You certainly wont regret a V8 conversion. Its not just the power, the car just gets so nice to drive.
Youre living in the right city for this. Adrian can sell you the nicest set of extractors you ever will see. He wants about a grand for them , but it is well worth it as they are a way better design than the stainless RV8 ones (which I have). You need to get them coated (jethot) but this means (aside from the heat insulation) they will end up looking far better than the stainless RV8 headers, which discolour. FYI the RV8 headers are around 550 pounds and when you factor in the exchange rate plus the 25% import tax you must pay(this was a surprise to me at the time!) , Adrians set start to look cheap!

Try and avoid the 3.5 motors. I bought one that had cracks in the block.I was told it would cost around two grand to fix, so I searched for a crack free block and after looking at 5 cracked blocks on a row, gave up on them. This is apparently a common problem in Australia. The 3.9 block was much revamped and strengthened and is a better motor in every way. This is what I ended up with. Triumph and Rover spares (in Adelaide again!) can sell you a NEW short hight comp motor for just under $3000. The 3.5 heads and front cover plus fuel injection etc all bolt onto the (much more powerful) 3.9 engine. The problem with the 3.5s is that the crank bolts loosen a little over time and the main bearings move a little, result small cracks start around the bolt holes. I believe that this loosening is caused by overheating the motor too often, something which would make the problem more prevalent in Australia than anywhere else. If you want to stick with the 3.5, and you find a good one, I am told the cure is to fix the bolts in place with Locktight super stud locker. I
Adapting the Hot wire EFI to fit under the bonnet will only cost you around $100 to have the plenum welded and (less than) 33mm machined off. Usually only around 28mm is needed. You also need to buy a couple of fuel pumps (around $150 and $100 each). I (and others) can give you all the details (gleaned from this and other sites) if you like. Having the rover plenum machined and carbi fitted and tuned will cost much more. Particularly in running costs. However many people prefer the look of the carbies. viva le difference.
Dellow can sell you the Yoke. He can also sell yo a reconditioned W58 supra gear box that has the D (or 21inch) gear lever base. The W58 has a 0.78 overdiven 5th gear. The other version (ieW55) have 0.82.
Ask him if he will do the bell housing with the one inch (or close to that) slave set up. The 0.5 inch supra slave is hopeless, way over driven and way too heavy for mere mortals. If you cant get the one inch slave (a one and one sixteenth off an old Holden in fact) you can adapt a one inch rover one readily enough, as I did.
I kept the original diff. Its easily strong enough (good to 230BHP) and I enjoy the rapid acceleration from zero to 80ks in second gear. I think a low first gear is still essential for traffic, carparks etc. Economy is still pretty good. I recently drove from Melbourne to Sydney and I was getting exactly 10km to the litre, with the top down at 110Km/hr the whole way :). Others prefer to change the axle over.
You dont need to buy a steady bar. You can very easily adapt the one that is on you car now. It is the one under the gearbox. This fits very neatly across the back of the engine from the head to the top corner of the foot well. The rubber part goes on the top of the foot well, bolted to a steel plate underneath via a small piece of shaped angle iron. I get no vibration at all from this and it holds the engine rock steady. The only effect is that the whole car rocks a little when I rev the engine. Something I dont mind at all :))

You might want to shop around a little for the oil pump base. Ive hear that some people are charging over $500. They are around 110 pounds in England eg It might be worth importing and there is a chance, if the package is small enough) that the customs wont tax you, if youre lucky. these guys also used to sell pump bases. They can also sell you a manual fly wheel and other bits.
As you know from the book, you can make your own mount engine brackets easily enough, however they also can be bought from a variety of places. Go for any that set the motor lower and back a bit further than usual. Obvious advantages with regard to bonnet and radiator clearance. Towery Foreign Cars (hes mentioned in Rogers Book) reportedly has a set of brackets that place the engine both lower and further back than most.
Adrians might do the same, I am unfamiliar with them.

The radiator core you have in your car is the V8 version, albeit with the top outlet on the other side. However it is a bit marginal. I got a very nice alloy radiator from race radiators in Dandenong, Melbourne. It cost $600 about three years ago. They do lots of these for MG workshops in Melbourne, who also do lots of V8 conversions. If you want to upgrade your brakes these MG workshops can also sell you a set of stainless hoses so that you might fit Volvo brakes. These hoses have an ADR number on them that make the new brakes legal. You can buy the whole ventilated disk brake upgrade off them if you cant be bothered getting the calliper adapted yourself. Adrian also sells volvo brake upgrades as well I believe.
The harmonic balancer from a Rover P5 or P6 is identical to the V8 one. An SD1 balancer is very similar except that it doesnt have the groove machined into the balancer itself. It actually worked out a lot better for me to use the SD1 balancer. The real advantage of these balancers is that they have long necks on them so that the steering rack may be tucked in under it. The alternator bracket off the P5 P6 is identical to the MG V8 one and can be got for around $30 at the most.

The good news is that most Rover/rangerover engine parts are interchangeable through out the years. This is just as well because if you find complete 3.9 out of a rangerover for example, you will need to change the front timing chain cover to the earlier one, so you can fit the oil base to it.
Best of Luck with it all
P.N. Sherman

Adrians gear


P.N. Sherman
P.N. Sherman

Thanks Peter

what exact conversion parts do i need ?
rover 3.5 v8's are really cheap and even a reconditioned one is still cheap
the price of the 3.9v8 is quite exspensive

im going to try and visit adrian's workshop and maybe triumph rover spares, im hoping their conversion parts are cheaps

Steve in Oz

Have a look through this site, pretty much every variation on theme here. Most of these people are very decent types, very ready to help you with problems.

First make a preliminary contact with an engineer. Ring the road traffic authority and they can give you a list, or try asking Adrian who he uses. It's pretty much a rubber stamp job but a wise man keeps the bureaucrats happy.
The motor-
Can be got from either a rover or range rover. Parts are interchangeable. The Range Rover front timing cover and water pump are different from the Rover one. These are shown on the Triumph and Rover site. Itís the same front as used on the RV8 (which had a shorter and much much more expensive water pump). I am using a range rover front (and standard long nosed water pump) but Iíve set my motor about an inch further back than usual. Most of the Range rover motors will be the low compression type, the Rover ones usually High compression. Note Low compression means lower power but more torque. Hence the Range Rover application. Low compression isnít a bad thing.
You are correct, the 3.5's can be inexpensive and as such are value for money, if you can a good one. However I paid $2400 for a very low Km 3.9 with all the EFI gear attached (private sale), which you might want to keep in mind when shopping around. However there must be plenty of good 3.5ís out there, just make sure you don't get a dud. You can check for bad cracking in the block very simply. If you take off the sump. You need to be insistent about this. You might promise to buy the motor if there are no cracks, or offer to buy the seller a new sump gasket if necessary. Remember I saw 5 lemons in a row.
Open this site
and scroll down to the photo of the 3.9 engine. About the 4th photo down. The 3.5 is very similar except that there is allot less metal around the crank bolts.
I found that small cracks were first visible one or both sides of where the bolts screw into the block of any of the middle three sets. A fine hairline crack appearing to be one or two centimetres long exactly in line with the bolt. I could see three of these cracks on my first motor and when I had the block fluoro tested there was cracking all through the block. This can lead to the cylinder sleeves slipping and other problems. If you do get a good one try the Locktight trick or possible try locking tabs, like on the brake callipers, on. That should fix it. Obviously a well maintained motor should never overheat however.....
If you go EFI motor try for the hot wire. The earlier federal version that went with the 3.5 motors had many reliability problems. I had difficulty giving away the EFI that came with my 3.5 motor. There are three stages to the EFI in range rovers in Australia. Best is version three, the post '89 (approximately) hot wire EFI, as fitted on the 3.9 engines. There is a photo of the manifold on the T and R spares site, with some expensive non standard electronics attached. Also Rogers book. site. down the bottom. (air flow meter not shown). This bolts onto and runs the 3.5 motor no problem. Called hot wire because it uses a heated wire to measure air flow into the motor. Air flow cools the wire and changes its resistance. Version one EFI was the very early Federal "flapper style" analogue EFI. This has a balanced mechanical flap on the intake that measures inflowing air. Obviously this flap can become damaged if the engine backfires. This EFI set up initially had a flat topped air intake (without trumpets) that later changed to the Hot Wire trumpet type manifold, but still with the Federal/flapper electronics. This intermediate stage I call stage two. Useful to know because you can fit the very superior hot wire gear to stage two air intake manifolds if you want to. People who own mid to late Ď80ís range rovers sometimes do this.
You can make the EFI air intake manifold fit under the MGB bonnet by altering the trumpet tray (T & R spares site again). You get a shop to weld up the three vacuum take offs and machine up to 16mm off the bottom and 11mm off the top of the tray. Should cost no more than $100.
The big advantage with the 3.5 is that the engineer should not ask you to get a brake upgrade, but he will ask you to pay for a brake fade test. If your brakes are in good condition then this should not be a problem. The car ends up about 30kg lighter, not heavier. One of the things to discuss when you make your preliminary contact with the engineer. If you do want to improve your brakes then Volvo callipers and Peugeot 505 ventilated disks can be made to fit. Shown on Adrian site I believe.
Oil pump base-
Three years ago Triumph rover spares used to sell oil pump bases for around $200. They might still do so. I bought mine from Clive wheatly (see above) for 75 pounds, but I notice his price has gone up.
Manual fly wheel out of a rover-P6 or SD1.
You'll be lucky to find one of these. However there are plenty of Range rover ones around than can be altered. You will have to machine about half an inch off the face of these. This is not just because a lighter fly wheel gives better performance in MGB's but because it won't fit in dellows bell housing otherwise! Triumph and rover spares sold me one already machined for $200. However the new bolt holes did have a very coarse thread which made fitting the pressure plate (also bought from them) tricky. You might do better to negotiate a fitted and balanced pressure plate that has locating dowels. Adrian might be a better bet, The after sales service from T and R spares is non existent, buyer beware.
Gear box & bell housing-
See previous remarks.
The best there is, in your own back yard and really worth every penny. I wish I had know about these headers before I bought the RV8 ones off Clive.
Radiator- you can make do with the one you have (should be OK with through the guards headers) or if you have overheating problems then simply ring up Race Radiators in Dandenong and simply ask for a MGB V8 radiator like they make for MG workshops. Race Radiators59 Bennett St Dandenong 3175(03) 9793 2798
Engine mount brackets (the ones that go on the block). You can make them, buy them from Adrian, Clive Wheatly or get a ďset the motor further back and lowerĒ set from Glenn
Infact if you are using the supra box then setting the motor and gear box further back gets you gear lever closer to the orrigional location. The longest supra gear lever setup is still about an inch shorter than standard . Making your own is not hard, I managed, but it is time consuming and if I do another MGBV8 Iíll buy a set off Glenn.
Adrians mounts might be similar, donít know.
P.N. Sherman

SD1 starter motor
SD1 harmonic balancer
Tail shaft.
a holden one that matches the MG flange has a much stronger flange and thicker wall.
W58 (best)supra box, or W55.
P.N. Sherman

This thread was discussed between 03/01/2007 and 09/01/2007

MG MGB GT V8 Factory Originals Technical index

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