The Engine; Crankcase; Flywheel And Crankshaft; Cylinder Block - Triumph SPEED TWIN 1945 Workshop Instruction Manual

CRANKCASE
maximum'rigidiry. The crankshaft
i s
supported by t w o heavy duty ball bearings i n
e i t h e r crankcase half. The camshafts are housed fore and aft i n the upper part o f
t h e crankcase and they operate i n phosphor bronze bushes. The camshaft fitted
t o operate the inlet push rods (both camshafts are identical) is so designed, t h a t
crankcase pressure is released t o atmosphere through a rotary disc valve. Located
i n t h e timing side crankcase are t h e timing gears, ancillary drive and the o i l pump.
FLYWHEEL A N D CRANKSHAFT
T h e balanced t w o t h r o w crankshaft, and flywheel are bolted together t o make a
complete unit. The "H" section connecting rods are forged from RR56 Hiduminium
alloy and the bottom caps are steel stampings lined w i t h white metal, the t w o parts
being bolted together w i t h t w o high-tensile bolts.
CYLINDER BLOCK
T w o types o f cylinder block are employed, one being cast from high grade cast-iron
and t h e other die cast from aluminium alioy. The
l a t t e r
i s fitted w i t h steel liners
w h i c h can be replaced when t h e existing liners are w o r n beyond their maximum
re-bore limits. Each cylinder drovides location for the tappet blocks and tappets.
PISTONS
The pistons are die-cast "LO-EX" aluminium alioy, each fitted w i t h t w o compression
and one scraper ring. The guvdgeon pins are
a
tight push
fit i n the pistons- and are
held i n position by spring steel circlips.
CYLINDER HEAD
The cylinder head houses the inlet and exhaust valves I n separate combustion
chambers. T w o separate rocker boxes complete w i t h the rockers are bolted t o
t h e head t o operate the valves. As w i t h the cylinder blocks, the heads are made
f r o m either cart-iron o r die-cast aluminium alloy. The latter have cast-iron valve
seats cart i n t o the head durlng the manufacture.
LUBRICATION
D r y sump lubrication Is employed. The system i s operated by a t w i n plunger
reciprocating o i l pump.
See page 27 for further information.
CARBURATION
Either by Arnal o r S.U. carburetter.
I G N I T I O N
Elther b y L u c u magneto o r Lucas
R M i 4
alternator.