Total disploment cu.in.
1 1 ±O,5
Max. power (at the wheel I kW (HPI 82 (I III
Max. engine speed r.p.m.
Under no circumstances the engine must goes over
10.000 r.p.m. (Sup.'921 ond I 1000 (S.P.'92 and S.P.S.I
"DESMODROMIC" (typel with four valves each cylinder, controlled
eight rocker arms
opening rocker arms and
close rocker arms)
and by two head camshahs. It is controlled by the driving shoft through
cylindricol geors, pulleys and toothed belts.
The Desmodromic Valve Geor System
IIOpening rocker orm (upperl.
2)Opening rocker arm adjuster.
4)Closing rocker arm
61Closing rocker orm (Iowerl
The valve opening and closing diagram is the following (detection
data with cleorance: 0.008 in. ond 0.039 in. Belt tension through
tool 88765.0999 at I 1.51
Inlet valve: in.
Opens before TD.C.
Closes aher BDC
Exhaust valve: in.
Opens before B.D.C
Closes after T.D.C
S.P. '92 Sup. '921
OOOSI 0039 Ooosjom9
73'153' 66' 44' 30':11,1
92' 71' 98' 73' 94' 170'
100'177" I 00'177' 84' 162'
64' 42' 64' 42' 44' 18'
valve tappets, with cold engine, must be:
Opening rocker arm:
................ 0006 .. 00067
Closing rocker arm:
Inlet and exhaust: in.
. .......... 0002 .. 00031
Measurements with a free play of: 0 in.
Inlet: in. .......................... ......
Exhaust: in. .............................
FUEL SYSTEM - IGNITION SYSTEM
. ........................ WEBER - lAW.
N' of injectors each cylinder: ....... I (Sup.'921, 2 (S.P.'92-S.P.S.I.
It is a timed sequential integrated system for ignition and iniection
This control is obtained by iniectors (6) having two stable operating
the iniector delivers fuel;
Closed: the injector does nol deliver fuel.
The central unit ( II can control the delivered fuel quantity by changing
the injectors opening times.
The ignition control is got by operating on an ignition system prOVided
with inductive discharge, consisting
(5) (one each cylin-
der) with the corresponding power modules (21
The control system "senses" the motor through a certain number
inputs connected to their corresponding sensors, each sensor has a
specific function to provide the central unit
with a complete
the motor operation:
- The motor sensor (141 sends a Signal allOWing the deteclion of the
motor rotating speed;
(1 1) provides a reference for the exact liming
iniection and ingnition;
- The throttle potenfiometer ( I 01 sends
signal as function of the
throttle valves opening angle;
- The absolute pressure sensor (81 sends a Signal as function
environmental barometric pressure;
- The water temperoture sensor (151 sends a signol as function of
the motor operative temperature;
- The air temperoture sensor (71 sends a signol as function
motor entering air temperature.
In order to optimize this system, a control strategy called
been adopted. The main inputs taken as reference
the system to
control iniection and ignition ore the throttle opening angle
the motor r.p.m. (N). In the central unit memory there are tables that
let correspond an iniection pulse time, an injection phase angle and
an ignition advance angle to a given r.p.m. and to a given throttle
opening angle. The other system inputs (water temperature, air
temperature, pressure, battery voltage) take part to the control by
changing the correction coefficients applied to the values prOVided by
the "Alfa/N" tables. Then the system introduces further corrections in
the operating conditions requiring particular ignition and feeding
features (ignition phase, qUick opening or closing
the gas control).
(fixed up to 950 r.p.m., then the control box varies this value
according to the signals it receives from the cam sensor).