Table Of ContentTHE SPORTS CAR ENGINE
ITS TUNING AND MODIFICATION
THE SPORTS CAR ENGINE
ITS TUNING AND MODIFICATION
*
COLIN CAMPBELL
M.Sc., A.M.I.Mech.E., M.S.A.E.
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
'963
© COLIN CAMPBELL 1963
ORIGINALLY PUBLISHED BY CHAPMAN & HALL LTD. 1963
SOff COVER REPRINT OF THE HARDCOVER 1ST EDITION 1963
SBN 412 07470 2
ISBN 978-0-412-02740-6 ISBN 978-1-4899-7204-0 (eBook)
DOI 10.1007/978-1-4899-7204-0
TO MY FATHER
who tuned motor cars before
tuning was invented
Show me the mechanic who pops out his chest and
announces 'I don't need any fancy gadgets to tune a car,
all I need is to listen to the engine.' Show me this man
and I will show you a }!_yjJer-ep,otistical DOPE.
ToM McCAHILL
Preface
I HAVE ATTEMPTED to write in one volume a textbook on the theory
of automotive engine tuning, always with a bias towards the more
highly developed type of engine as used in the modern sports car.
Engine tuning is treated in its two aspects, basic tuning and super
tuning, i.e. the modification of a stock engine to increase the power
output.
A supertuned engine operates with a tighter margin of safety
than a stock engine and a loss of basic tune can soon lead to over
heating, even to catastrophic failure. With this in mind the major
part of the book concentrates on the theory and practice of basic
tuning. Chapters are devoted to the ignition system, to carburettors
and to the methods used in 'trouble-shooting'. All of this is of value
to the owner-mechanic, the garage man and the trainee racing
mechanic. Supertuning is the subject of Chapters Nine to Thirteen.
Here I attempt to take the magic out of supertuning. So many of
the latest methods used in the British, German, Italian and American
tune-shops are based on knowledge obtained in the engine labora
tories of universities, colleges and commercial research institutions
throughout the world. Much of this knowledge is available to all
of us, if we take the trouble to ferret it out. From time to time
throughout the book the reader will see references to experimental
work of this kind. The final chapter is on the mechanics of modifica
tion. By providing practical hints on the ways and means of engine
modification this chapter should help to preserve the balance
between theory and practice.
I am especially grateful to the editor of Sporting Motorist for
permission to reproduce certain material used in Chapters Four,
Five and Six, which appeared originally in that excellent journal
as a series of articles on carburettor tuning.
CoLIN CAMPBELL
Racine, Wisconsin, U.S.A.
vii
Contents
Preface vii
CHAPTER ONE
General Principles
TUNING FOR PEAK EFFICIENCY AND POWER; \-\'here does the power
go? The energy in the fuel. Cycle efficiency losses. Combustion
losses. Transmission losses. THE PENALTY OF POOR TUNE, SUPER
TUNING: Making it breathe; make it efficient; making it reliable.
CHAPTER TWO
Instruments 17
TuNING INSTRUMENTS; The dynamometer. Garage instruments:
tachometer; vacuum gauge; compression pressure gauge; fuel
pressure gauge; stop-watch; voltmeter and ammeter. SPECIALIST
INSTRUMENTS. Battery tester; ignition timing light; distributor
analyser; tach-dwell meter; coil tester; condenser tester; plug
tester; exhaust gas analyser; stroboscope; cathode ray oscilloscope.
CHAPTER THREE
The Ignition System 42
Ignition requirements. The primary circuit. The secondary
circuit. Secondary voltage variations. The phenomena of the
spark. Sparking plug and contact breaker gaps. Dwell angle.
Ignition timing. Sparking plugs. MAGNETOS: principles; types;
care and maintenance.
CHAPTER FOUR
Mixture Formation, Distribution and Carburation 59
The mixture. The boiling point range. Mixture and power.
Distribution. Formation of the mixture. Manifold design. Pressure
losses by distribution. THE MIXTURE REQ.UIREMENTS OF THE ENGINE;
Starting and cold-running; idling; part-throttle operation; full
throttle; acceleration.
CHAPTER FIVE
Variable Choke Carburettors 74
THE S.U. CARBURETTOR: Starting; idling; full throttle and cruis
ing; acceleration. The HD type. The HS type. Tuning the S.U.
carburettor. Vacuum gauge technique. Multiple carburettors.
Tuning after modification. THE S.U. TWIN-CHOKE CARBURETTOR.
IX
X CONTENTS
CHAPTER SIX
Fixed Choke Carburettors 91
WoRKING PRINCIPLES: Mixture compensation; starting; idling;
full throttle; acceleration. THE ZENITH: Series VN; Series W.
THE SoLEX: Type 32 Bl; Type B 28 ZIC-2; Type C. 35 APAI-G.
TuNING THE SoLEX. Tuning after modification. THE WEBER: the
auxiliary venturi. The Type DCO. Tuning the \Veber.
CTTA PTER SEVEN
Testing and Tuning 129
The Importance of Testing. TESTING: The 11 Tests: initial road
test; compression test; plug test; vacuum reading; battery test;
coil and starter voltage; coil and condenser tests; contact breaker
tests; fuel pump tests; mixture strength readings; valve clearances.
TUNING: Tuning operations: valve clearance setting; sparking
plugs; distributor; ignition timing; carburettors; final road-test.
C:IL\PTER EICIIT
Trouble-Shooting 149
Fault-finding with the vacuum gauge: valve trouble; induction
leaks; broken piston rings; defective exhaust system. A short
catalogue of troubles: bad starting; low speed misfires; high-speed
misfire; overheating; fuel pump troubles.
C:IIAPTER NINE
Combustion Efficiency 170
THE BASIC PRINCIPLES OF SUPER TUNING: Combustion efficiency.
Mechanical efficiency. Friction and pumping losses. The com
pression ratio. Abnormal combustion. Knock. Other combustion
abnormalities: rumble; pre-ignition; running-on. Combustion
chamber shape: bath-tub head; wedge head; hemispherical head;
ovrrht"ad inlet, side exhaust head.
CHAPTER TEN
Volumetric Efficiency 192
Definition. How to Improve Volumetric Efficiency. THE INDUC
TION PROCESS: Inlet valve timing. Overlap. INLET VALVE AND
THROAT DESIGN: The air flow rig. Flow calculations. Mean gas velo·
city at valve throat. Mean gas velocity at valve seat. Carburettor
venturi size. Valve seats. Valve throat and port design. Venturi
ports. Curved ports. THE EXHAUST PROCESS: Exhaust valve si:te.
EXHAUST VALVE THROAT AND PORT SHAPE.
CONTENTS Xl
CHAPTER ELEVEN
Special Techniques 223
MuLTI-CARBURETTORs: One choke per cylinder. Experimental
measurements. Recommended pipe lengths. PETROL INJECTION:
Port injection systems; Rochester/Corvette; Lucas/Jaguar; Mer
cedes Benz 300 SL. THE INTAKE AIR: Cold air intakes. .Forward
ram intakes. RAMMING EXHAUST PIPES: Branched exhaust pipes.
NEW IGNITION TECHNIQ.UES: Transistorised systems; electro-mag
netic systems; piezo-electric systems.
CHAPTER TWELVE
Cams and Blowers 254
SPECIAL CAMSHAFTs: Factory options and re-grinds. The cam
profile. The actual valve motion. Spring surge. Cam-face wear.
When to fit a high-lift camshaft. BLOWERS: The mechanics of
supercharging: Vane type; Roots type; Centrifugal type. SuPER
CHARGER TUNING TIPS: Heat rejection; Blowing through the car
burettor; Carburation for blowing; The drive. TuRBOCHARC11NG:
Corvair; Oldsmobile.
CHAPTER THIRTEE:\"
The Mechanics of Modification 275
CYLINDER HEAD WORK: Compression ratios and how to change
them. Measuring the clearance volume. High compression
pistons. Machining methods. Work on the ports. INCREASING THE
LIFE OF COMPONENTS: Crack detection. Shot peening. Balancing.
WoRK ON THE VALVE GEAR: Push-rods. Tappets. Rockers.
Springs. CONNECTING RODS, PISTONS. SPARKING PLUGS. EXHAUST
VALVE MATERIALs: Exhaust valve troubles.
APPENDICES
1. Special Camshafts 298
2. Champion Engineering Racing Division Heat Range
Comparison Chart 310
3. Suggested Maximum Torque Values 312
4. S.A.E. Horse Power 314
Index 317
