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MG MGB GT V8 Factory Originals Technical - I've got my Engine

I have finally got my engine!!! A Rover SE V8 kindly gave its life up so my MGB could live. The engine is still in the Car and is running well, has 130K on the clock and it has a federal type fuel Injection System. Unfortunaly the car is an auto. I was wondering what sorts of things I should be also considering using from the car such as water pump, crank pully, distributor or injection system for my conversion. The details of the car as far as I know is 82-83 Rover SE automatic and the engine is a 21A block (the stronger one supposedly) Any advice would be appreicated.

Clem Spriggs

Keep the injection system as this was the first system I used back in 1984. The pwoer on a well set up engine is not restricted by a significant degree by the injection. The main restriction is the ECU maps and here there are a number of alternative ECU's for Rover Vitesse and Range Rovers that will plug in and give a marked difference in perfromance. I know I used to have 8 different spec ECU's and two adjustable ones along with 4 alternative chips courtesy of Lucas.

Also rip out the fuel tank as this contains a swirl pot which can be removed and used in the MGB tank to prevent fuel surge stopping the engine evry time the pick up becomes uncovered during cornering when the fuel level is belwo about half a tank.

Also remove the fuel pump which is a Bosch injection unit that delivers a max of 4.1bar pressure. There is also a fuel pump resister that drops voltage to the pump as you only need up to 2.5 bar of the pumps performance. The resister slows the pump speed which eases wear and also makes life quieter. The latter point being more important in hotter climates as the hotter the pump the more noise generated. Also make sure you remove the fuel pump mounting bracket as this incorporates sound deadening.

I don't know if there are any convertors in your neck of the woods who convert axles, but the SD1 axle has been used in about 80 UK conversions after being narrowed and fitted with the TR8 style of propshaft flange in place of the long nose extension of the SD1. MGB rear hubs have also been fitted to the SD1 axles in some conversions. If no one is available to convert the axle then it may occupy too much space and weight to keep.

The rev counter has also provided the inner working for an 8 cyl tach conversion finto an MGB unit so save that.

Trace the wiring loom through. Normally the V8 injection system uses a separate loom that means it is reasonably easy to remove. Take the opportunity of removing as much of the main wiring as possible as there are so many uses for bits of wire, connectors and other bits and pieces later.

Make sure you get the complete distributor AND the wiring between it and the amplifier unit. also relaim as much wire into the main loom. It is far easier to know what conection goes to what much later on when you have a section of original wire with the appropriate colour codes still attached to the unit.

I am not sure which brake set up will have been fitted to your Rover, but there are two options, a twin piston unit or a 4 piston unit. The twin piston unit has a piston diameter of 57mm which is 3mm larger than the MGB units. These units have been used on MGBs to provide increased brake effort (with slightly longer pedal travel) and the 12mm thick (8mm standard) V8 spec discs.

If you Rover has the 4 piston caliper then it probably uses a ventilated disc. Still keep these as there are vented discs that can be adapted and the 4 pot caliper is another favorite choice. If the disc is solid then this caliper can still be used to provide a larger pad contact area as the 41mm diameter pistons equate to the 57mm twin pot units. (Of interest the Rv8 uses a 4 pot with 38mm dia pistons which equate to the 54mm twin pot MGB units.) Bolting any of these calipers to the MGB stub axle invvolves nothing more than the use of some late Triumph GT6 shouldered bolts!

Nothing else immediately comes to mind, but if it does I will leave a note.

Roger Parker

Thanks for the info there is obviously alot more stuff that I can borrow off my donor car than I first thought. With the injection system does it fit under the bonnet with out modification of does it require the manifold to be lowered. As I was looking at the manifold set up and there does not look to be much room between the hot water circulator under the throttle body and the rocker cover.

Clem Spriggs

Onya Clem, u are now part of the V8 Brigade!!!
a couple of pointers i may make..... from my own experience

The injection system does not fit under the bonnet..if its the single throttle body system you can machine a few mm's off the plenum chamber so it can fit but
if its the latter( and better) twin throttle (on Vittese's i think)u cannot machine it and thus have to have a lump in your bonnet..

Also about brakes re Roger Parker and Clem, go to MG Workshops in Melbourne.. they have a front kit which uses Nissan 300zx Rotors with Volvo ventilated 4 spot calipers, they can also add Nissan Pintara twin spot calipers etc to the rear as well if u choose to have on of their diffs.



I am not clear on the date change for the Australian spec engines, but the original injection development was know during development here as the Australian/Federal system. This used a two piece manifold set up with a clearly flat top plenum with the eight fixing bolts clearly visible. (for a picture see the cover of Roger Williams's book 'How to Give the MGB V8 Power'. That cover shot shows this system and is in fact my old system that has bee replaced by the later Hot Wire type.

If you have the three piece manifold which has the ribbed and domed top with six fixings then this is the much taller Vitesse design which was commonised for later (1985 on) Range Rover, and with slight modifications the Hot Wire. (1988 to 1994) In fact the later (1995 on) GEMS 8 system used a further modified manifold of which parts can still be interchanged. The current system is now a Bosch one with a completely different manifold which first appeared on the new Discovery and which has standardised on Range Rover over the last 12 months.

The oddity is the twin plenum which is in truth better described as a twin throttle. This is a rare beast and the reality was that it is not as good as it is made out to be. I have seen a couple of alternative development designs that actuall grew from the stillborn supercharged programme. This was a twin inlet system and was worth somethign between 20 and 30 bhp on its own. Politics prevented this from going beyond development.

The Vitesse appeared at teh October 1982 Motor Show, which was the first appearance of the Vitesse style injection, so your car is in the build period when this design was about. If it is this type then there are a number of conversions very effectively done that reduce the height of the plenum and ram stack housing (the central part of the three pieces) which enables the system to fit under the standard MGB lid. Engine mountings are critical in achieving the best engine position to get this under the bonnet too.

I have modified a later Hot Wire system, which uses the same castings. This is able to fit under the standard MGB bonnet, just, and involved machining of the plenum and ram stack housing.

Conversion to injection provides many driving benefits but don't underestimate the extra work involved. The fitting of a carb set up is childs play by comparison.

Roger Parker

Thanks for the input about the injection system. I'm pretty sure that it is an early federal injection system with the single throttle body (like on the cover of Roger William's book) so I should be in luck. The idea of using this injection system does not scare me as I have a prototype injection system on the workshop bench that I'm building. Being an electrical engineer does have it's benefits. The only reason I can't use my prototype as it is still in the intial stages of production. Atleast once I get my system up and running I'll be able to use all the fuel rails, injectors, pump and manifold from the old system and I promise to put how to list on this page.

On to the other bits of the engine can I use the cranks shaft pully as suggested in Roger Williams book (split three parts of the pully and machine a groove??) and can I use the water pump?


Clem Spriggs


just another point id like to add is that you may want to use an aftermarket ECU system , which is programmable and can be made alot easier.
Im a computer engineer and since your an electronics one it should be fine

I have the Haltech Engine Management system which is so easy to programme
plug my laptop in, run the program while the car is running and presto every air/fuel mixture etc etc is visible and changeable, (and makes people riding in Buses and trucks think what the hell is that in the passenger seat??? )
you may also like to try the Motec system as well
but thats big $$$%
the Haltech is about 2000. the motec system is double that


Spriggsie, you should be able to use the water pump. Cut the shaft off in front of the pulley. Use a disc in an angle grinder. You'll be too old to drive the car by the time you cut it with a hacksaw. If the pulley falls off the hub, it's a simple task to secure it. There is a locating peg for the pulley on the hub. Drill & tap 2 or 3 symetrical holes (120 or 90 degrees) & countersink the pulley holes. Secure with 2 or 3 countersunk screws & some Loctite.I think I used 10-32 threads from memory.
If you haven't already bought the gearbox, why not give the auto trans a try & spend your bread on the diff.? A manual sounds sporty, but in reality ,there's so much torque with the V8 that you never have to change gear hardly. The auto is better around town & you can fit a cruise control for long trips. Barrie E.

you could try the wolf 2d ecu $800 which is completley programable rev cutout data logging,
with a hand controller which is allso a neat dashboard
comes with a rover 3500 map.
or you could try the 3d ecu witch has ignition control
allso throw the dissy away . rover electronic ign not much good anyway.see our web site for more info on wolf ecu's.

This thread was discussed between 29/04/2000 and 02/05/2000

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