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l?ngine
Four stroke, four cylinder monobloc with detachable wet sleeve
cylinder liners; bore
3½
in.
(88·9
mm.). Stroke
4
in.
(101·6
mm.), cu.hie
capacity 154 cu. in. (2,523 c.c.). Firing order, 1, 2, 4, 3; cast camshaft
driven by helical gear from crankshaft. Counterbalanced crankshaft,
statically and dynamically balanced, supported in three main bearings of
the thin, steel-hacked white-metal replaceable type; journals
2·248
in.
diameter, front
2·032
in. long, centre
1·910
in. long, rear
2·188
in. long.
Big end bearings replaceable thin steel-hacked white-metal lined type,
crank pins
2 · 122
in. �iameter x
1 ·501
in. long. Cast iron pistons using two
compression and one scraper rings above gudgeon pin.
Valve 6ear
Overhead valves, non-interchangeable inlet and exhaust, operated by
tappets and push rods. Lift
fir
in. Head diameters : inlet
li
in., exhaust
1¾ in. Clearances : inlet
0·015
in., exhaust
0·022
in. Timing: inlet opens
5
°
after T.D.C., closes
35
°
after B.D.C. Exhaust opens
42
°
before B.D.C.,
closes T.n.C. Single valve springs, split cotters, clearance adjusting screws
at rockers.
Lubrication
Full force feed to crankshaft and camshaft bearings, by-pass feed to
valve rocker shaft. Crankshaft drilled for lubrication of big ends. Gear
type pump, driven from camshaft by skew gears. Relief valve set to
25
lb ..
sq. in. Pressure indicator on dashboard. By-pass oil cleaner with replaceable
fabric element. Dipstick level gauge. Capacity of sump,
12
pints.
Manifold System
Normal one-piece type· manifold with automatically controlled hot
spot. Air cleaner of oil bath type. Air intake pipe connected to pre-heater
on exhaust manifold and provided with an adjustable sleeve to regulate
amount of cold air drawn into the carburettor.
Fuel System
Gravity feed from overhead tank. Tank capacity : Vaporizing oil
10
gallons, Petrol
l½
gallons. Three-position tap on tank bracket. Solex
carburettor
30
F.V., gauze filter at intake union.
Mechanical governor, controls engine through entire speed range to
maximum· of
2,000
r.p.m. Intermediate catch position on governor lever
to give
1,300
r.p.m.
PAGE 41