How to Improve MGB, MGC & MGB V8: New Updated and Enlarged 2nd Edition

First printed in paperback format in 2006.

First published in ebook format 2015 by Veloce Publishing Limited, Veloce House, Parkway Farm Business Park, Middle Farm Way, Poundbury, Dorchester, Dorset, DT1 3AR, England – Fax 01305 250479 – e-mail [email protected] – web www.veloce.co.uk or digital.veloce.co.uk.

Ebook edition ISBN: 978-1-845848-31-6

Paperback edition ISBN: 978-1-845841-87-4

© Roger Williams and Veloce Publishing 2015. All rights reserved. With the exception of quoting brief passages for the purpose of review, no part of this publication may be recorded, reproduced or transmitted by any means, including photocopying, without the written permission of Veloce Publishing Ltd. Throughout this book logos, model names and designations, etc, have been used for the purposes of identification, illustration and decoration. Such names are the property of the trademark holder as this is not an official publication.

Readers with ideas for automotive books, or books on other transport or related hobby subjects, are invited to write to the editorial director of Veloce Publishing at the above address.

All Ebook design and code produced in-house by Veloce Publishing.

Contents

Acknowledgements & about the author

Foreword

Introduction and using this book

Points to note

Chapter 1. Planning an upgrade/conversion

Plan conservatively

Starter upgrades

Conclusion

Chapter 2. More powerful four-cylinder engines

The capacity

Incremental bore sizes

Cylinder heads

Weber carburettors

DGV

DCOE

Supercharging

Exhaust manifolds & systems

Chapter 3. The MGC 6-cylinder engine

Engine out of car

Improving the breathing

Upgrading the camshaft

Balancing

Breathing

Weber DCOEs

Increasing the capacity

Engine upgrade summary

Engine assembly tips

Unleading/porting a cylinder head

Chapter 4. Upgrading V8 engines

Introduction

Improving your 3528cc engine

Oil pressure/flow

Speedier oil return

Priming the oil pump

Sumps and gaskets

Flywheels

Compression ratios (CR)

4.0/4.6 replacement engines

3.9-litre/243ci – 94.04mm/3.7in bore + 71.1mm/2.8in stroke

4.0-litre/243ci – 94.04 mm/3.7in bore + 71.1 mm/2.8in stroke

4.2-litre/258ci – 94.04mm/3.7in bore + 77.0mm/3.03in stroke

4.6-litre/283ci – 94.04mm/3.7in bore + 82.0mm/3.22in stroke

Oil filters/coolers

Oil pump variations

Turnkey uprated engines

Other tips

Camshaft/followers

Transplanting EFI engines

Starter motors

Crankcase breathers and filler

Further reading

Chapter 5. V6 engine conversions

Introduction to V6 engines

Bodyshell alterations

Front-wheel drive donor engines

Rear-wheel drive donors

Common issues

Cooling the beast

Engine management

Rev counter/tacho

Exhaust routes

Sump/oil pan clearance

Power steering

Rear axle ratios

Chapter 6. 5-speed gearbox improvements

Alternative MGB gearboxes

MGC Gearboxes

Gearboxes for V6 engines

Gearboxes for V8 engines

T5 5-speed

Toyota 5-speed

Rover SD1 & Triumph TR7

MG RV8 gearbox

Clutch actuation

Master cylinders

Slave cylinders

Automatic gearboxes

Chapter 7. The rear suspension, axle & prop/driveshaft

Tweaking the current design

Telescopic rear dampers

Anti-tramp/traction bars

Rear spring changes

Lowering

Stronger

Composites

Parabolics

Upgrading live axle suspension

‘3/4-link’ located suspension

‘4/5-link’ method

Live rear axles

Independent rear suspension

Drivetrain detail

Limited slip differentials (LSDs)

Prop/driveshafts

Chapter 8. Front suspension & steering

Stiffening the front suspension

Lowering

Anti-roll/sway bars and handling kits

Improving steering

Negative camber wishbones

Caster angle wedges

Polyurethane suspension bushes

Power-assisted steering

Quick racks

Bump steer

Shock absorber/damper improvements

Asymmetrical/offset dampers

Symmetrical/central damper

Coil-over spring/damper combinations

Moss-Europe

Hoyle Engineering

Replacement front crossmember assembly

Chapter 9. Upgrading the brakes

What’s important

Front caliper options

Rover SD1/Vitesse calipers

Hoyle Engineering kits

Princess four-pots

Radial-mounted calipers

Hi-Spec Motorsport

AP Racing calipers

Wilwood

Front discs/rotors

One-piece rotors

Two-piece discs

Brake servos/boosters and master cylinders

The rear brakes

Proportioning/bias/balance/pressure-reducing valves

Residual pressure valves

Rear disc brakes

Chapter 10. Wheels & tyres

Wheel diameter

Rim widths

Road wheel offsets

Central wheel patterns

Wire wheels

Tyres

Profiles

Tyre diameter calculations

Chapter 11. Heating, cooling & air-conditioning

Heater improvements

The full implication of cooling

The radiator

Coolant flow

Radiator fans

Bonnet louvres

Insulation

Reflective foil

Exhaust wrapping

Metallic-ceramic coating

Oil cooler

Fitting air-conditioning

The basic components

MGB/C/V6/V8 fitting specifics

MG evaporators

MGB/C/V8 condensers

Other suggestions

Kit of parts

Wiring up air-con

Chapter 12. Bodyshell, interior & trim changes

Bodyshell changes

Widening the wheelarches

Rubber to chrome-bumper conversions

Front and rear valances

Fibreglass bumper upgrades

Headlamp improvements

Improved fittings

Smaller spare wheels

Increasing a Roadster’s capacity

Extending the GT’s rear floor

Comfort and security

Screen washing

Door locks

Glove pocket

Windstops

Interior trim and carpets

Seats

Cabriolet hoods

New Heritage bodyshells

The 3-synchro shell

New V8 bodyshells

Corrosion protection

Chapter 13. Improving the sparks

Low-tension system

How it works

Retro-fitted breakerless systems

Optimising the timing

Performance distributors

High-tension components

Distributor caps/arms

Sparkplugs

The plug leads

Charging the ignition coil

Saturating the coil

A final consideration

Computer ignition management

Chapter 14. Carburettor induction

Carburetor designs

Fuel atomisation

The SU carburetor

Types of SU

Road tuning, stage 1

Road tuning, stage 2

Road tuning, stage 3

Track day/competition tuning

Larger/more SUs

Insulation

V6 and V8 Induction Improvements

Holley/Weber comparisons

AFB inlet manifolds

AFB air filters

Fuel pumps, filters & pressure regulators

Chapter 15. Electronic fuel-injection & engine management

How EFI works

MGB/C/V6/8 fuel supply

ECU triggers

Controlling fuelling

TPS inlet manifolds and throttle bodies

Lumenition

Omex

Webcon-Alpha

‘V’ MAP engine management

Programmable ECUs

Further reading

Chapter 16. Electrics, lights & instruments

Electrical power requirements

New alternators

Connecting an alternator

Replacement/upgraded wiring looms

Power distribution

Connectors

Safety considerations

Halogen headlights

Xenon lights

Modern Volkswagen Beetle lights

Fuses

Rear light improvements

Emergency flashers

Audible warning/flashing direction light

Windscreen washers

Aftermarket starters

Instruments and controls

Overdrive logic controller

Wiring routes

Instruments

Electrical security measures

Chapter 17. Weight watchers

Unsprung weight

Weight outside the wheelbase

Weight located high in the car

The engine

Chapter 18. Conclusion

Appendix. Supplier index

Further reading

Acknowledgements & about the author

Acknowledgements

I would sincerely like to thank the many people who assisted with the preparation of this book. There are too many to list them all individually, but I would especially like to record my appreciation to the following, without whom the book would have remained a ‘first edition.’ Roger Parker of the MG Owners’ Club for generously providing information and photographs, for reading the draft manuscript and making innumerable valuable contributions. Kurt Schley, founder of British V8 Newsletter, and Dan Masters of Advance Auto Wire for their invaluable help by way of information from the USA and electrical information, checks and diagrams. I am also indebted to Dan for the superb cover picture of his significantly improved MGB. Doug Smith of MG Motorsport, Richard Jenvey of Jenvey Dynamics Ltd, Sean Brown of Flowspeed, Dann Wade of British Car Conversions, Bill Guzman of Classic Conversions Engineering, and John Hoyle of Hoyle Engineering. Jim Stuart and Tom Hoagland for their help and guidance, and photographs of air-conditioning installations, and last but certainly not least, to Roche Bentley of the MG Owners’ Club for his support and Foreword.

About the author

Roger Williams was born in 1940 in Cardiff, was brought up in Guildford, and attended Guildford Royal Grammar School. Aircraft became his first love, and he joined the de Havilland Aircraft Company as a production-engineering apprentice and very quickly added motor cars to his list of prime interests. During the ensuing six years he not only completed his apprenticeship and studies, but built two Ford-based ‘specials,’ and started on a career in the manufacturing engineering industry as a production engineer. Works managerial and directorial posts followed, and these responsibilities, together with his family commitments, severely restricted his time for motoring interests.

Roger’s business interests moved on to company doctoring, which he enjoyed for some ten years, specialising in turning around ailing engineering businesses. In 1986 he started his own business, improving client profitability by interim management or consulting assignments, and was able to renew his motoring interests.

Roger, who now lives in retirement with his wife in France, has owned several MGBs, a Stag, and a TR6, all of which he rebuilt himself. Roger’s spare time is devoted to classic motor cars or writing, he has two married daughters, enjoys golf, and is a Fellow of the Institution of Mechanical Engineers and a Fellow of the Institution of Engineering and Technology.

Foreword

We MG owners are extremely fortunate. Of all the classic marques no other is better served for spares, technical support and good advice. There are many books, too. Some are pictorial, others give advice on repairs and restoration, and this author’s first book was warmly received by enthusiasts eager to learn more about modifying and improving their chosen model. This latest edition will be essential reading, too, for any owner of an MGB, MGC or V8. It features a wider range of modifications, taking into account different tastes and parts availability, from all over the world. It also covers the vast range of personalisation that so many owners wish to complete on their cars, most of which, of course, is thoroughly tasteful and not destructive to the original car. Thus, should fashion, perceptions and values change substantially in the future, the vast majority of improved MGs can be returned to original specification.

But why would anyone want to do that? I believe that the so-called purist who insists on originality will become as extinct as the dodo. MGs always benefited from well thought out improvements. Today, the desire to use leather and wood instead of plastic and vinyl continues, and there are positive moves to add more beneficial changes, such as five-speed gearboxes which are more efficient and allow better fuel economy. On the same theme, there is a greater desire to use modern technology, such as the very flexible use of electronics to control the engine which results in greater efficiency, and many other positive improvements that would have been an impossible dream in the days these cars were made. This book keeps track of both the small and major options.

The designers of the original specification cars would have loved to include most, if not all, of the improvements that an owner can now add to his MG, but obviously the selling price and the tough competition dictated what could be included. An owner who tastefully improves his MG is simply doing what the original creators would probably have done if they hadn’t been constrained by budgets, and the fact that some of the better technology hadn’t yet been invented. Thank-you Roger for helping many more of us improve our MGs; your effort is really appreciated by us all.

Roche Bentley

Founder and Club Secretary,

MG Owners’ Club

Introduction and using this book

Introduction

We live in a technologically-based, ever-shrinking world these days. A fast-changing one, too; just consider how television, air travel, telecommunications, computers and the motor car have changed in our lifetimes, young or old. Although the MGB died (at least in production terms) in 1980, I am delighted to say that, nevertheless, it has not been untouched by progress. The Rover Group may not make complete MGBs any longer, but its development work has been both commendable and exciting in recent years. Considerable efforts and innovation can also be seen from numerous specialist suppliers, with many new ideas coming to the market in recent years. So many, in fact, that I felt my recent review of the MGB V8 conversion scene in How to give your MGB V8 Power warranted a wider view. Although there is reference to MGB V8s here, I have allowed myself to cover areas relevant to MGB four-cylinder upgrades, V6 conversions, 3000cc MGCs, and, of course, the related GT versions. I hope this offering will be helpful to a wide range of MG enthusiasts.

Because there are a great many MGB enthusiasts in the USA, not to mention numerous improvement projects under way there, too, I have ensured the book addresses UK and US suppliers. Local conditions can change the emphasis or importance of a feature, and suppliers differ on each side of the Atlantic. As a consequence, this book incorporates features that, I hope, will satisfy most enthusiasts, regardless of location.

Using this book

As stated in the introduction, the primary purpose of this book is to guide you through a variety of high-quality but balanced improvements for your MGB, MGC, MGB V8, and their GT variants.

By reading this book you will know exactly what improvements are available, what each entails, and generally receive an opinion as to what development is most compatible for your improvements. Hopefully, this will enable you to plan the most cost-effective and efficient way to achieve exactly the final specification you require – regardless of which MGB/C/V8 is to be the basis, and whether or not you do the work yourself. The author has tried to grade each improvement as to its compatibility with other improvements and changes listed. There seems little point in fitting a 4600cc V8 engine developing some 300+bhp and fitting inadequate front brakes or failing to adequately improve the suspension systems. Conversely, although less dangerous, it is possibly a waste of money to fit a top-of-the-range front suspension/brake assembly if you plan a very modest increase in 1800cc engine power and car performance. Please accept that the assessments can be only a general guide and, in the absence of a definitive measure, are usually based upon engine capacity. Clearly, a highly-tuned 1950cc-engined car driven very quickly may warrant higher specification brakes or suspension components than an untuned 3947cc V8 conversion driven very conservatively. The assessments cannot take variations of this type into account.

In the light of growing expectations for modern facilities within a classic style, two significant innovations have been added to the traditional MGB/C/V8 upgrades ... modern V6 engine conversions, and fitting air-conditioning.

Points to note

All of the components/service prices are approximately those prevailing in the UK at the time of publication. These prices will be subject to normal market forces and will, of course, tend to rise with economic inflation. You would be well advised to allow for these factors when calculating your budget.

It’s possible that the goods and services referred to will become unavailable or altered with the passage of time.

Dimensions given in illustrations are in millimetres, unless otherwise noted. Line illustrations are not to scale.

Note that references to right side and left side are from the point of view of standing behind the car.

This book is not intended to be a workshop manual or general restoration guide, as there are a number of publications available which cover maintenance, repair and restoration in great detail: you probably already have such books on your shelves. Therefore, this book does not describe mechanical procedures which are standard and which do not relate directly to the improvements or modifications required.

Important! During work of any type on your car, your personal safety must always be your prime consideration. You must not undertake any of the work described in this book yourself unless you have sufficient experience, aptitude and a good enough workshop and equipment to ensure your personal safety.

The author, editors, publisher and retailer cannot accept any responsibility for personal injury, mechanical damage or financial loss which results by errors or omission in the information given. If this disclaimer is not acceptable to you, please immediately return, unused, your pristine book and receipt to your retailer who will refund the purchase price paid.

Veloce Publishing Ltd

Chapter 1

Planning an upgrade/conversion

Plan Conservatively

When I wrote the first edition of this book some 10 years ago there were already many ways to improve your MGB, C or V8. This edition is also written from the standpoint that you have an MGB, C or V8 and would like to improve its performance in one, or perhaps a number of ways. Consequently, I have given over no space to originality issues. The range of products and opportunities has grown in the intervening years, probably making the MGB/C/V8 range the most post-production-developed cars in use today. Thus the options have multiplied several fold, but so have the costs and the difficulty of selection.

The original MGB/C/V8 models were basic cars employing simple technology. The increased choices of today sound great (and absolutely no-one is complaining!), but the greater variety brings with it the need to choose wisely, particularly from the value-for-money, budgeting and compatibility points of view. Selection is sometimes made no easier by the fact that the complexity of some products (and the technology employed) is out of the experience of many enthusiasts, and puts greater emphasis on the fine-tuning and detailed adjustment of the car than ever before. So, if you understand the basics of electronics or boost pressures, or the consequences of pre-ignition, then advances in technology should present few problems. If you don’t, as may be the case with some readers, this book will help you select wisely.

If you find you’re getting out of your depth with any of these technologies then you should stick with what you understand and feel comfortable with. Once the complexities start to get beyond you, opt for one of several conservative approaches. For example, buy your upgrades in kit form. The trade recognises that not every owner will be familiar with the technology involved in some upgrades, and helps owners by assembling pre-tested kits, which usually include comprehensive fitting, assembly and testing instructions. Ask to see those instructions and enquire about after-sales technical advice.

If you’re still unsure, find a specialist within the MG trade with experience of fitting the relevant kit(s). Ask for a quotation, ask about the warranty period and coverage, and assign the fitting task to them. These approaches will unquestionably cost more, but the resultant upgrade should work well, and carry the reassurance of a warranty.

Another prudent/conservative approach is to buy all your upgrade parts for each project from one supplier and at the same time. That’s not to say you should buy from the first supplier you approach, however; shop around.

Don’t feel obliged to carry out all the changes you would like to make to the car in one session. There’s nothing wrong with planning your upgrade over several phases spanning, perhaps, several years.

It really is worthwhile spending time planning your upgrade or conversion. Part of the planning and preparation process involves visiting suppliers and exhibitions/trade shows. But don’t stop there – talk to existing users of upgraded cars at your local club and local/national meeting. Tour the car park looking at similar models to yours, or examples of the model you plan to buy, and ask the owners about their experience with a particular upgrade or kit. Most will be delighted to help and give you the benefit of their experience.

Prepare yourself for the fact that the larger the engine upgrade you opt for, the larger the number and the greater the extent of the changes you’ll be required to make – collectively generating big expense if you choose the most powerful of engine options, such as that shown in picture 1-1.

1-1 This ex-Rover engine has been extensively modified and rebuilt, and will be generating 250bhp. Consequently, almost every mechanical component in the car will require upgrading which, although not a problem, costs (since this is a US car) big bucks! Note the, as yet uncovered, air-conditioning, and the very attractive and appropriate MG replica rocker covers.

The resulting car needs to be safe and a pleasure to drive, so the conversion must be a balanced one – i.e. all the constituent components must not only fit together, but must also be suited to each other.

Your plan will be influenced by the time you can devote to the project, by the skills and equipment available, or by the car, engine or gearbox you have in the garage. The car, but more specifically the condition of the bodyshell, must be a major consideration. It really is foolhardy to think you can drop a very powerful engine into a tired, rusting bodyshell. In fact, if your bodyshell is in poor shape then you should think more about a restoration project than an engine transplant or upgrade. Only if the shell is (really) sound should you contemplate increasing the power under the bonnet.

The number of options is vast, and the ones you choose will depend entirely on where you’re starting from and where you want to get. Perhaps the car in photo 1-2 appeals; or perhaps you see the V6 conversion in picture 1-3 as your ideal way to introduce modern technology; or maybe you’d just like the car to have softer rear suspension. No two projects will be the same, and you need to assess your priorities and plan accordingly. Time planning is never wasted, and I hope this first chapter will have already set you thinking, if only to ensure that your project is completed and within your parameters.

1-2 This four-door ‘stretched limo’ style ‘B’ certainly got my attention. I wonder how it drives?

1-3 This 60-degree Generation 2 GM V6 was originally fitted to a front wheel drive car but has been transposed to this MGB, bringing with it multi-point fuel injection (hence the FI cast into the top cover) and multi-coil ignition where, in this case, 3 coils serve the 6 plugs. This design improves the saturation of each coil. Here, centre picture, we are actually looking at the 3 coils. You may be able to follow the ignition leads from each coil – one to each bank of cylinders. We will return to coil-saturation times in chapter 13.

If you’re thinking of buying an MGB/C/V8 specifically for an improvement project, base your purchasing considerations around the bodyshell; its condition being paramount. However, if you’re planning a V8 conversion bear in mind that the post-1976 MGBs accept the Rover V8 engine, seen in photo 1-4, with little or no modification.

1-4 This is an original MGB GT V8 engine bay. You can easily replicate the engine installation but the air filters are now unobtainable, though there are a variety of products on the market today which perform the same function.

starter upgrades

This book is full of complex, expensive and technologically-advanced upgrade options that I hope you will enjoy reading about. However, an upgrade doesn’t have to be a major, technically-challenging or hugely-expensive one. Nor does it have to be carried out in one session. As examples we will spend a few minutes exploring two of what I consider the easiest, quickest and most cost effective ‘starter’ upgrades. This should illustrate that you don’t have to employ hugely complex installations to get a lot of satisfaction and fun from a lower level of technology, and also how you can usually divide up a project.

This book has four chapters of engine information and one each on gearbox and rear-axle options, so graphic detail here is superfluous. Neither of these ‘starter’ options will provide the fastest cars on the block but could be an ideal route to rejuvenating a solid example of the most popular of the models covered – the MGB. Either suggestion could enable recent owners to get that bit more from a, perhaps, mechanically tired ’B. The engine and gearbox options available to you depend on which MGB you have, but the rear suspension that I propose in this ‘taster’ chapter is common to chrome/rubber-bumper MGB, C and V8 models and will, therefore, be the first item we explore. I have no affiliations to any manufacturer, but I think a four trailing-link rear suspension setup (as shown in picture 1-5) offers huge benefits for the MGB/C/V8 owner when coupled to coil-over spring/damper units. This design is offered by one US and one UK supplier, and is explained in more detail in Chapter 7. This upgrade would be my recommendation for either of the engine/gearbox combinations that follow, and can be installed separately from the engine/gearbox upgrade as phase one of your plan.

1-5 This is Frontline-Costello’s UK-made trailing-link rear suspension. I think these four-/five-link kits locate the rear axle well, and, with a pair of coil-over suspension units, commendably improve all aspects of the MGB/C/V8 rear suspension.

Engine/gearbox option 1

If you have a chrome-bumper car, I would suggest a conservative starter upgrade using your existing, or a similar, four-cylinder engine, and increasing its capacity to 1870cc. Have the original cylinder head professionally gas-flowed, and choose a modest aftermarket camshaft. Initially, refit all the original carburation and exhaust equipment but, as phase three of the upgrade, you may care to revisit the exhaust system, air filters and carburation/needles, as evident in photograph 1-6. For a gearbox, I would choose a conversion kit that utilises the Ford Sierra 5-speed gearbox illustrated at 1-7. It’s lighter than the original MG overdrive gearboxes, and a well-reconditioned Ford unit will last for years. This, together with a new clutch and your rebuilt engine would go in as phase two.

1-6 The owner of this 1870cc MGB engine has, appropriately, ensured that breathing is as efficient as practical by fitting richer needles to the SU carburettors, and free-flowing air filters.

1-7 The extremely compact Ford 5-speed gearbox, shown here courtesy of Graham Robson, was used on several Ford vehicles. Also known as a Ford ‘Type-9’ gearbox, the Sierra is the most frequent donor, at least in the UK.

Engine/gearbox option 2

However, even better performance and more relaxed driving is available to rubber-bumper owners via a low-cost V8 conversion. It doesn’t have to be a tuned engine, nor even a refurbished one, to transform the car into a genuine performance sports car that is far superior to the original. Most 3500cc ex-Rover SD1 V8s will still have useful life left if they’ve been serviced and done no more than 100,000 miles. You’ll need to change the front crankshaft pulley and oil pump, as shown in picture 1-8, the water pump, alternator cradle and exhaust manifold/headers. There is now the option of retaining the original front end found on SD1, Range Rover-spec engines and RV8s, although the alternator bracket and front anti-roll/sway bar would have to be the RV8 style unit available from the MG Owners Club. I would also suggest that you change the camshaft, cam followers and the carburation arrangement, the latter to avoid bonnet/hood interference problems (see picture 1-9). This option is more complex than option 1, and perhaps requires more phases, but the end result will be worth it!

1-8 The V8 oil pump casing comes in two halves – the top (which houses the actual gears) is integral with many front timing covers, while the base, seen here, distributes the oil to a remote filter and, if required, a cooler.

1-9 There are various carburation options allowing Rover V8 engines to squeeze under the MG bonnet/hood, and we saw one in picture 1-1. This is a cheaper solution utilising a modified Rover SD1 inlet manifold, a new replica ‘V’ casting, and the original carburettors.

The Rover V8 engine can be found in the USA in a variety of guises. Rover engines are available, but 215ci Buick/Oldsmobile/Pontiac units are still around and offer the same light weight as the later Rover SD1 units, and will fit provided you change the sump/oil pan for the SD1 sump, shown in picture 1-10.

1-10 Of interest solely to Buick and Rover P6 engine users, but this SD1 sump/oil pan is more recessed at the front and is necessary when fitting a V8 into the MGB.

It’s a good idea to upgrade the front brakes during your first phase, certainly before effecting the engine upgrade, and install the improved rear suspension and increase the speed-rating and size of the tyres, too (possibly including a modest wheel increment) as phase two.

Phase three is unavoidably large, involving fitting the engine/gearbox/clutch and all the exhaust/carburation changes in one go. Use a Rover V8 bellhousing and any Rover 5-speed LT77 (or later R380) gearbox from TR7, Rover 2300/2600/3500 SD1/MG RV8 cars. Photograph 1-11 shows an ex-TR7 box, but be sure yours is this 5-speed version.

1-11 Rover’s tough ‘LT77’ 5-speed manual gearbox was used in a variety of British Leyland cars and vans, but was probably least stressed in its TR7 role shown here. The bellhousing will need to be swapped for a Rover V8 version.

The rear axle ratio also needs to be uprated to a 3.07/3.08 ratio, requiring an expert to fit a new crown wheel pinion/ring gear if you’re to enjoy the relaxed cruising this engine offers – and this is probably best carried out as phase four.

Conclusion

Viewed as one simultaneous upgrade, a project can seem daunting, but split into logical ‘bite-size’ steps it takes on more manageable proportions. Planning the conversion is a very important contribution to a successful outcome. Part of your thinking will involve what you plan to do yourself and what (and where) you need to subcontract.

You need to be mindful of safety issues even at the planning stage. Buying/hiring/borrowing the correct equipment comes into the planning stage, but it’s also important to prepare your plan with safety in mind by prioritising brakes and suspension improvements before power upgrades.

Develop your plan, progressively incorporating more detail, and remember; planning is rarely wasted.

Chapter 2

More powerful four-cylinder engines

Although the MGB is (justifiably) very popular, by today’s standards the car is unquestionably ponderous in 1800cc and standard tune. It is possible to get more horsepower out of the 1800cc engine, of course, and some excellent books have been written on the subject, and some admirable tuning companies have worked their art on the ‘B’s’ original heart. For many enthusiasts, particularly those keen on originality, tuning the original engine is as far as they will wish to go. Their views are to be respected, of course, and are as much a valid part of the MG scene as those, like myself, who wish to see their MGBs perform more like modern cars. To put the rest of the chapter into context, the accompanying information shows what these experts can do with a mid-production 1798cc engine.

Tune: Standard

Maximum Power: 65 @ 4510

Maximum Torque: 104 @ 2500

Tune: Stage 1

Maxmimum Power: 80 @ 4380

Maximum Torque: 106 @ 3300

Tune: Stage 2

Maximum Power: 97 @ 4860

Maximum Torque: 130 @ 3200

Although the gains can be in the order of 35-40%, and are, therefore, undoubtedly very beneficial, I won’t explore tuning in great detail here because there are already some excellent and detailed books on the subject. Instead, I propose to explore some alternatives which will be equally productive. However, as with engine tuning, you still need to remember that rarely – note that I do not say never – can anyone maximise the effectiveness of an engine by a single magic improvement. Numerous performance enhancing products are sold as single, bolt-on improvements, and, of course, they do just what the vendors promise. However, to maximise the effect one needs to look at the whole engine. Distributor, timing, delivery of the spark, camshafts, carburation and exhaust systems all intertwine and need to be compatible with each other. Most of these details will be explored later in the book.

I intend to explore changing the mechanics of the original four-cylinder engine, and this is best achieved by viewing the engine as three, initially separate, major components:

Enlarged cubic capacity – the bore and stroke of the engine.

Alternative cylinder heads.

The external bolt-on products that are available to help.

The Capacity

Any bottom-end work, regardless of capacity, is best confined to 5-bearing units using tuftride-hardened crankshaft journals, and with the rotating parts fully balanced.

Few readers will need me to go into more initial detail than to say the original engine had a common capacity of 1798cc (109.8cu in) from its 80.26mm (3.16in) bore x 88.9 (3.5in) stroke right throughout MGB production. However, the power and torque generated varied significantly, depending upon the year of manufacture, the market it was made for, the compression ratio, the camshaft and carburation, and the environmental equipment fitted. Generally, the early 5-bearing engines introduced in October 1964 and recognised from engine number 18GB onwards, produced the best outputs, of about 95bhp at the flywheel, with ‘high’ compression (8.8:1) for UK/European markets. Sadly, this fell to about 60bhp towards the end of the car’s lifetime for some markets, notably the USA, where compression was reduced to 8.0:1, decimating the car’s sporty characteristics. Incidentally, the increased weight of the car’s rubber bumpers also played a part in reducing its performance, but we’ll explore remedial detail later in the book.

I cannot encourage you all to throw the stifling environmental equipment away, but, where practical, this, along with an increase in compression ratio, would benefit performance, as would some of the following capacity increases. There is a saying which goes: There’s no substitute for cubes. Generally speaking this is true, in that tuning can increase the power available, but it doesn’t usually have the same beneficial effect on torque, driveability and acceleration. Increasing the capacity of the engine, with no other changes, also lowers the engine’s usable ‘power band’ (in terms of revs per minute). The detail of incremental capacity is perhaps more easily explained if I divide the expansion into two sections – boring and stroking.

Incremental bore sizes

You will see a variety of enlarged capacity MGB engines on offer – 1870, 1950, 2000 and 2100cc all spring immediately to mind. These increased capacities are all the result of increasing the bore of the engine by varying amounts and, in the latter case, the length of the stroke as well. The capacity of an engine is, of course, a product of the area of each piston multiplied by the number of pistons multiplied by the stroke. Thus, the bore diameter, which we’ll explore first, is the major factor in determining the capacity of our MGB engine.

1870cc

The first step in the expanded bore sequence involves boring each cylinder to 81.79mm (3.16in +0.060in) and using the maximum MGB oversize pistons available, such as those shown in picture 2-1-1. Other changes are, of course, highly desirable, and we’ll discuss some options as the book progresses. However, to give you some idea as to the effect of