TIMING
THE
ENGINE
The camwheels, timing pinion and intermediate wheel which mesh together are
suitably marked
;
when these marks coincide with each other, the valve timing
is
correct.
Fig.
19
clearly illustrates the timing' for the respective models.
NOTE: When the engine crankshaft has been rotated the marks on the gears
will not
coincide due to the uneven number of gear teeth until the crankshaft has been
turned a considerable number of times. The timing, of course, is not aKected.
TIM)
FITTED
WITH
RACING CAMS
E.3134
The marking on the camwheels
is
not sufficiently accurate for timing the vaive
operation for racing purposes.
It
will be noted that the carnwheel hrs three keyways
provided to enable the operator to obtain accuracy of approximately plus or minus
2i
degrees.
The following valve timing instructions are given assuming that the engine has been
fitted with racing cams and
is
now installed in the vice (Fig.
9,
page
42)
with the
rocker boxes, timing gears and timing cover
still
to be fitted.
Exhaust Rocker Box. Assemble the exhaust rocker box and the timing side push
rod to the cylinder head.
Fit the holding bolts and nuts and tighten down.
Tappet Adjustment.
Ensure that the tappet
is
on the base of the cam and then
adjust the rocker pin to give 0.020" (0.50 mm.) clearance between the pin and the
vaive tip.
At
a
later stage, to check the opening of the valve a
D.T.I.
(dial test indicator)
should be fixed to the engine. If the operator
is
not
in
possession of such an
instrument the clearance given above should be increased to
0.025"(0.60
rnrn.)
when checking.
checking
T.D.C.
Fit
a
degree timing disc to the drive side engine mainshaft and
fix a pointer in any convenient location. Turn the crankshaft until the pistons are at
T.D.C., then set the disc and pointer to read
0
degrees and clamp up firmly. To
ensure that the pistons are at true T.D.C.. turn the crankshaft backwards until the
piston is say
lv
(4
cms.) down the stroke. Note the reading on the disc. Now turn
the crankshaft forward until the pistons are again
If"
(4
cms.) down the stroke. The
disc reading should be the same. If not correct, re-adjust the disc or pointer. Particular
care should be exercised to ensure accurate T.D.C. setting.
EXHAUST CAMSHAFT TlMlNG
Setting the Crankshaft. Turn the crankshaft forward until the disc reading
is
55 degrees before B.D.C.
Setting the Exhaust Camshaft.
Rotate the camshaft "CLOCKWISE" until all
play between the rocker adjuster pin and v2lve tip
is
taken up.
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