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MG MGB GT V8 Factory Originals Technical - Howto Rover V8 Conversion

I am looking to start collecting information on a RV8 conversion of My '78 RB MGB (It has been converted to chrome).

I am currently running a 2L fast road engine, but I really want a V8.

Been a late RB car it should make the conversion much easier, or so I am lead to believe.

I am currently working on the suspension and brakes and am quite happy doing this ad-hoc as I go allong.
I am looking for a guide on how to swap the B series out and drop the V8 in. I was thinking about getting a running EFI engine from a SD1 / Vitesses, how much work is involved in getting this in?

Really I am looking to get as much done before the engine comes out as to take the off road time to a minimum, anyone guess the off road time of just the engine swap + plumbing?

Many thanks
paul at fryer dot org dot uk
Paul Fryer

Paul, the Sd1 Vitesse is a good route to go....I went this way and do not regret it, plenty of low down torque, and reasonabl fuel efficient. First get the 'bible'......How to give your MGB V8 power.....most of your questions will be answered.......Most UK V8 converters are on the MGOC BBS regularly, plenty of UK help there.

Good luck with the conversion....I'm sure that you will not regret it !
M Barnfather


Mike allredy told you about the engine.
You should also look for the oil pump adapter, MG manifilds, radiator (or have your's recored and modified) and for a suitable axle. A 3.3 or 3.09 rearend should be on your list.

Although i only run on Holley carb, i am still love the performance. I did my conversion in the early 80's. I am sure you will see what you have missed with your B up to now.


I'd get the earlier version of the book to start with, nice and simple. The later one is overload for a beginner, and much of the new stuff in it is geared towards our American friends.

Liam H

Quote: "I was thinking about getting a running EFI engine from a SD1 / Vitesses, how much work is involved in getting this in?"

Here are a few detailed articles on that specifically:
Another article on Rover EFI installation will appear later this month in the new issue of the newsletter.

As other specific questions come up, try the searchable back-issue archive available FREE here:

If you use a Toyota supra W58 gear box with the 21 inch (longest) gear lever extention you do not have to do anything about the top of the transmission tunnel. It is also a very smooth gearbox, as well as compact, it is VERY strong.
Dellow in Sydney (he ships world wide) makes adaptor bellhousings for anything from 600 to 900 australian dollars depending on how many bits you want. Ask for the one inch clutch slave, which works well with the MGB master. Don't get the 0.75" supra one.

These are the best extractors availiable

however closer to home


Peter Sherman

For the EFI fuel supply use two in line pumps pulling through a large filter. Use a very late MGB fuel sender that has its own fuel uptack in it. See the thread below about fuel senders for the whys and wherefores.
Just in case you can get them locally, the feeder pump I use is made by Pierburg in Germany and is called an "Auto-suction vane cell pump". stock no. 12001. it can deliver 0.5 bar when used as a primary pump. It cost $95 Australian (apply exchange rate to get an idea what it might cost locally).
The main high pressure pump is a Bosh one pt no 0580464070 and cost $140.
Peter Sherman


You will unfortunately receive loads of conflicting advice, largely because there is no one 'correct' way of doing a conversion.

In the UK we tend to go for just the Bosch pump from an SD1 or Jaguar (E bay has plenty on offer), mounted at outlet level in front of the tank.

M Barnfather

Thanks for all your help so far, I am waiting for my book before I go much further with engine planning.

A quick question on brakes, I am looking at the brake calipers (4 Pot) single line from the SD1 ( which are suposed to be a straight conversion (May require bolt sleves from 12mm to 7/16), but can I use stock MGB V8 brake discs?
Are the V8 discs vented?
Can you get vented and groved discs quite easyly?
Paul Fryer

There's plenty in the archives about brakes. The V8 discs are not vented. If you do want vented, many in the UK have used the Peugeot 505 (Turbo) vented discs, which are easy to source. The overall dimensions are fine, but they have to be re-drilled match the 4-bolt pattern of the MGB hub.

The Princess and SD1 (Lockheed/AP) 4-pot calipers are very similar in design, but the SD1 version is bigger / heavier, with larger piston bores. The SD1 calipers will work, but the Princess version is generally seen as a better option (if you can get them!) as the overall piston bore area is very close to standard MGB (retaining the correct brake pedal "gearing"). If not already fitted, both the SD1 and Princess calipers require spacer kits to be fitted if you are using vented discs. If you do decide to go the SD1 route I can sell you a set from an SD1 Vitesse that have the spacer kit fitted (would need reconditioning)....but of the 2 types, I would still recommend the Princess option.
Pete Green

I'm running Sd1 Vitesse calipers, and Peugeot vented disks, the caliper bolt holes need sleeving down to MGB caliper bolts, and the disks need drilling for 4 studs.

The pedal travel is greater than standard, and I'm not sure that they are that much better than the 'standard' Princess ones, unless you are going to do some seriously heavy braking on a regular basis.
M Barnfather

Do you have a swirl pot? Or do you just pump direct from the tank to the injectors? If so, does it ever give a problem with a low tank level?

Sorry there's so many questions.
Mike H
Mike Howlett

Yep, I bought one of the last swirl-pot converted RB tanks....the guy who made them packed it in.......keep the questions coming via here rather than e mail, as others can chip in with their views.
M Barnfather

The advantage of the in line pumps
petrol tank-->Big Filter-->feeder pump-->Main high pressure pump-->engine-->return to tank-->

is that you do not need a swirl pot. The half litre filter is more than adequate. I've had less than 7 litres in the tank and gave it a pretty good test on that occasion. No problems at all. This was when I had to replace a damaged fuel tank so I know exactly how much fuel went in.
This means all your parts are 'off the shelf' and may be replaced very easily. That includes the tank.
If you use a later model Fuel gauge sender this has its own fuel uptake line in it.
You must use a filter with EFI rollervane pumps because they will be destroyed by any debris. I tried and lasted about an hour without one. The high pressure pumps draw fuel poorly and become noisy if you try to pull though a filter. Particularly when the petrol warms up a bit. The vapour pressure of petrol at 37.8 deg C is around 70KPa. Translation, lots and lots of gas bubbles, poor syphon and a cavitating pump delivering poor pressure. Use a feeder pump and the problems go away. Jags and GM use dual pumps.
This has run absolutly problem free for about 50,000 kms and three years now.

Brakes- MGB brakes are good. Your car will get lighter by about 20 to 40 kg, not heavier so unless you need to, or really just want to, stay with standard. The green stuff pads have a good rep'. You can also remove the disk covers/back plates from the wheels and fit cooling ducts from the front valance to the disks if you think cooling is a problem.
My engineer required me to fit a brake upgrade. Since I wanted to have the car legal I had to do something.
I used Volvo 240 DL brake callipers. Like these
you need to redrill the holes. They work extremely well, pedal travel feel identical.
Willwood also do brakes.
Peter Sherman

Peter, do you mean that you have the feeder pump after the filter? I had assumed you had tank > feeder pump > filter > high pressure pump > engine > return. What happens to your system if air gets drawn into the filter?
And can you remind me what car your filter came from please?
Mike (still unsure what to do)
Mike Howlett

My efi was originally a flap-valve one from a Rover SD1 Vitesse, the filter was mounted in the engine bay after the pump but before the pressure regulator....I've stuck with this system, mounting the filter on the N/S scuttle where the brake/clutch cylinders would be on a LHD car......I have not had a pump failure yet in something like 40.000 miles (famous last words ?)
M Barnfather

"No filter" Mike B. a man living on the edge. I salute you. I'm not so lucky.

Yes Mike H,
Filter first. Feeder (or sucker pump) second. It’s about half a litre in size. The bigger the better. Range rovers were on the list of suitable applications on the box. I’m not at home for the next week so can’t measure the outlet size for you. Fuel line size was the determining factor. It is a generic one and cost around $20 at Kmart. I bought the last one (different brand, slightly smaller) at an auto shop and it cost $24. So cheap and easy is the message.
The feeder pump is made by Pierburg (Auto-suction vane cell pump. Stock no. 12001.) and is easily able to suck through the large filter. As well as being a filter, the large filter acts as a swirl pot, or antisurge buffer. The very late model MGB fuel gauge sender (pt # ADU 3218) pick up locates right next to the old pick up at the very bottom of the tank., so very little air has a chance of getting sucked in.
The fact that the return is close to the uptake probably helps as well.

Worse case senerio’s;
New empty filter- a short 5 seconds "Bzzt" cavitating noise then the usual "humm".
There have been instances when I have braked sharply on a steep hill with a nearly empty tank and I will hear a brief “buzzt” noise, then it returns to the usual faint “humm”. No engine problems. Any air will just shoot around the top of the injector rail and back to the tank (I guess).
The feeder pump has enough suction capacity to easily and very quickly overcome any vapour lock/ air issues. By itself, the main pump has poor suction and takes much longer to pull a vapour lock through the line, hence loss of fuel pressure. Nothing really dramatic, I did try running without a feeder pump and what you get is a VERY noisy pump (which aside from spoiling the ambiance, can’t be good for it) and a slight unevenness in the motor so it doesn’t run too well when the tank gets low, or the weather gets hot. It did stall a few times on hot days.
On really hot days (35C plus) in traffic, again when the tank is again nearly empty (needle just above the E), and the fuel tank quite warm, the feeder pump will start to get a little bit louder, the occasional “Bzzt”, but it will keep the main pump supplied no problems.
In winter you don’t get this at all
Peter Sherman

The fuel delivery set-up that I have is slightly different but seems to cover all the issues. I've retained the stock SU pump and feed it through a filter (5/16" line size) to the top of an external surge tank. The tank is nothing more than a piece of 2 1/4" exhuast pipe tubing with a couple of pieces of 16 guage steel plates welded to the ends. It's got two 5/16" anad one 1/4" barbed fittings on the top and a single 3/8" barbed fitting on the bottom. The 3/8" fitting feeds the high pressure EFI pump by gravity. The HP pump feeds the fuel rail through an HP filter. The return line from the fuel rail feeds back through a 5/16" to the top of the tank and the 1/4" line returns the overflow to the tank. To slow the SU pump down, I've addded a 1/16" orifice the the fuel tank return line. I'm not completerly convinced that the return line to the tank is even necessary. As is, the system operates at atmospheric pressure up to the HP pump and downstrem of the regulator on the fuel rail. If I do away with the fuel tank return line, then it will operate at the SU pump shut-off pressure, 2-3 psi. The surge tank, HP pump and filter are mounted in the passenger's side battery box (It's a '73). One of the advantages of this system is that I didn't have to modify the stock fuel tank or sender. The fuel tank return line is the return line from the evaporative cannister that I removed. The return is routed through the water separator, which is now vented to atmosphere. The prevents the fuel tank from going negative pressure. So far, so good, but I've only got a couple of thousand miles on it.
Steve Mc

Thanks to all who have contributed, especially to Peter who has described his system many times on this BBS. I'm attracted to it because of its simplicity. I would love to see a picture of the set up if possible, particularly the Fuel Filter. No such thing can be seen on the Kmart website and I can't visualise what it looks like. Also I've not been able to find any reference on the web to the Pierburg 12001 pump. Even Pierburg's own site doesn't list it. There must be lots of alternatives - how about one of the commonly available Pacet pumps?

I've been trying out the fit of the hot-wire components under my RV8 bonnet, and I'm dismayed to find that even with the bulge, it won't close. I've done some careful measurements through the open grille aperture and I reckon I need at least 16 mm off the height to get the bonnet shut. This has surprised me, but I think the reason is that I am using a chrome bumper cross member so can't get the engine really low. It is currently sitting with the front of the sump just about 8 mm off the steering rack and I don't think I want to go any lower. So it looks like I will need to start shaving the trumpet base. Ho hum.

Mike H
Mike Howlett


You can take quite a lot off the trumpet base, mine's down to 35mm total height,but you will have to remove the water heater under the inlet to do this, as the gap above the rocker cover is critical., and also you may have to bend the fuel rail retaining straps I think.

Will this be sufficient, I can't remember how tall it was originally ?
M Barnfather

Mine is 54mm at the moment, so you took 19mm off. Did you have both top and bottom faces machined? I should get away with 16mm which everyone says I can take all off the bottom face.

I don't see how you can bend down the fuel rail. The connections to the injectors appear to be rigid. Can you give any more info on this?

Mike Howlett

I don't currently own a digital camera, must get on some day.
12001 was on the receipt, the supplier could have got it wrong. Anyway,
that looks like the pump, second one down.
looks like there are a number of versions of this, depending on what terminals you want. Pages 75, 76, 78.

also Glenn uses Jag pumps, about half way down.

The fuel filter, just go into a shop and pick out a nice big one. Made of metal, a bit of pipe sticking out of each end to attach a line to. The original Rover filter should be fine, a big three inch in diameter filter.
Steves home made external swirl pot seems OK, but you will still require a feeder pump, and I don’t trust that SU. Roller vane pumps are designed to run full speed all the time, diaphragm pump not so. Steve your outlet back to the tank is necessary. I Initially tried putting a T piece into the line just before the inlet of the high pressure pump, and feeding both the return line and the supply from the tank into it. There was a filter just before and after the T piece. The supply pump was a Subaru diaphragm pump. The idea was that the high pressure pump would circulate the fuel through the injector rail, and the diaphragm pump would “top up “ the loop.
What happened was it would run until the fuel warmed up, then stop, vapour locked!

That your sump is over the steering rack indicates that your engine is too far forward.
My rack locates under the neck of the harmonic balancer, as do all MGBV8’s
If you are using the caste engine brackets, you may have them reversed. I am using home made ones very much like the ones Glenn uses. If you look at them you can see that they displace place the rubber mounts far forward, so the engine goes back.
You can also see Glenns leg bending technique, which he developed.
Personaly I would not like to take more than 16mm off the bottom.
This is my approach, developed from the advice of others. Cut and past here.
I will tell you the maximum that you can take of each component and you can decide what
you want to do.

There is the section of the manifold that locates in the valley of the V (of the 8).
On this are the eight fuel injectors and the fuel rail above them and some sensors.
Don’t touch this, too hard.

There is the trumpet tray, in which the eight trumpets locate.
Before you do anything, measure the height difference between the 4 middle trumpets and
the two pairs either end. Write this down somewhere. These trumpets locate at different
heights because they are meant to even out the length of the air passages through the
inlet manifold. The trumpets are infact identical however they locate on different
height shoulders in the trumpet tray. When the bottom of the tray is machined the two
pairs of shoulders at the ends disappear and the two pairs of end trumpets need to be
shortened to maintain the height difference.

Covering the trumpet tray is the cover/throttle mechanism.

On the cover, under the throttle mechanism just over the port side rocker cover, is a
small bolt on water heater about 20 mm thick. Unbolt this and throw it away. Fill in
the bolt holes. I did this by epoxi-ing in some bolts and grinding off the heads,
flat. If you have an aluminium welder (I don’t) you can weld them.
You can remove 5 to 6 mm off the bottom of this cover if you really need to. It is
probably not necessary.
The trumpet tray-
Remove the 8 trumpets. You can do this by putting the tray in an ordinary household
oven and then pulling them out by hand. The aluminium expands more than the steel when
heated. You may even be able to pull these things out with out heating.
Get the machine shop to weld up the three vacuum take offs on the starboard side then
grind off the remnants. The three remnant bumps on the bottom must go. Make it tidy.
Then get them to machine up to 16mm off the bottom of the tray.
Flip the tray over and machine up to 10 or even 11mm off the top.
Refit the four middle trumpets (I used "ultra grey" silicon adhesive), then cut enough
off the two pairs of end trumpets so that you maintain the height difference that you
measured in the beginning.
If you removed 5 or 6 mm of the top cover as well , then you must shorten the middle
trumpets 5 or 6 mm.
The most you can take off the plenum/air intake assembly is 33mm because this drops the
throttle mechanism right down on top off the rocker cover. That’s why you needed to
remove the throttle heater. You should not have to machine more than 28mm off, in
I would suggest that you fit your motor, remove the trumpet tray , and substitute a
stack of paper (or something). Gradually reduce this stack until you can just get the
bonnet closed. Measure the stack. Then have the trumpet tray machined appropriately.

I had two goes at this because initially I had the engine half an inch higher than it
is now. Initially I had them machine 16mm off the bottom of the tray, 12mm off the top
of the tray (1 or 2 mm too much I believe) and 5mm off the top cover. This worked just
fine, but I had to take great care doing up the 6 plenum cover bolts. Not much thread
for them. You need to buy shorter bolts, or cut them.
Later I dropped the engine down half an inch and then got another tray and got them to
machine 14mm off the bottom and 4mm off the top.
There is a bonus to be got here. I noticed a distinct increase in power. Because I kept
the same trumpets I had an extra 8mm of clearance between the top cover and the
trumpets. Better air flow. I have found since that people like RPI will sell you
shortened trumpets. So I would recommend shortening your trumpets a little more than
you need.

Peter Sherman
Peter Sherman

Excellent 'how to do' Peter (I'd forgotten about shortening the plenum bolts).

That should give Mike loads of room.

Mike. I seem to recall that the fuel rail retaining straps had to be bent as the rail had to drop down because of the lowered plenum base.

Peter makes an interesting point about shortened trumpets, the information which I was given was that shortening trumpets raises increases HP at the expense of bottom end torque, I've got very short 45mm trumpets and 65mm throttle plate, off (I think) a TVR, b ut my wheel torque is 199 lb/ft@4080 RPM according to the rolling road.

I'm attaching a pic of lowerered plenum base.

M Barnfather

Great information Peter and Mike. I don't think my engine is too far forward. The gear lever on the LT77 'box comes right at the back of the tunnel cut-out, and the rocker covers are very close to the bulkheads. In fact I will have to "dog-leg" the gear lever slightly to allow all gears to be selected. The very front bolts of the sump pan are over the rack.

I removed the trumpets this morning in the oven at 210 Celcius - my lady was out. Terrible smell from the hot components, but the trumpets came out easily. Off to see my machine-shop pal this week. I reckon that 16mm off the bottom of the tray will be enough with the RV8 humped bonnet. I still can't see how you can bend down the fuel rail. The pipework that feeds the injectors seems too rigid.

Thanks again,
Mike Howlett


It was the brackets which I had to bend (you can see three of them in the pic) as my rail sat too tall otherwise.
M Barnfather

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

MG MGB GT V8 Factory Originals Technical index

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