MG Midget J1 1933 Instruction Manual page 62

Having removed all four nuts, take off the valve g,ear cover and turn the
engin,e by the starting handle until the timing marks o n the spiral bevel gears
coincide. These will bring the driving yoke o n the cylinder head across the
engine, and the driving yoke on th,e dynamo parallel to the engine centre
line. T h e bolts themselves may now be withdrawn, care being taken not to
lose the distance washers, which must be replaced in the same position.
Removal of the bolts enables the flexible coupling t o be withdrawn.
Detach the two cables o n the distributor side of the dynamo noting from
which terminal they are removed.
Now unscrew th,e four set screws which attach the dynamo to its platform
at the front of the engine thus releasing the dynamo.
Lift
the dynamo
approximately a quart~er of an inch and tilt i t towards the near side of the car
until the driving yoke o n the dynamo is just clsear of that on the cylinder head
T h e dynamo can tben be tilted forwards and easily withdrawn.
Replacement of the dynamo is effect,ed in the reverse way, but i t is
necessary to make sur,e that the engine timing has not b'e'en disturbed while
the dynamo was removed. Removal of the rectangular cov'er p1at.e in the
clutch housing should reveal the timing mark on the flywheel for Nos.
l
and 4
cylinders, exactly in the centre of th,e opening. Place the brass packing
pieces which fit under the dynamo base in position o n the dynamo platform,
making sure that you replace the same number that you took off.
If
for an,$
reason the dynamo is replaced by anoth'er, i t may be necessary to readjust
the mesh of the driving gears to obtain silent running by suitable selection of
the packing shims used. T u r n the dynamo spindle until the timing mark
on the dynamo driv'e gear coincides with the centr,e line of the dynamo and
is at the rear, that is, ready for engagemsent with the correspondingly marked
teeth of the drive gear on the crankshaft. Th,e holes in the dynamo coupling
yoke will then be parallel with the engine centre line. Tilting th'e dynamo
towards the near side of th,e car and holding the dynamo coupling yoke in
this position, insert the drive gear into the opening of the dynamo platform
and swing the dynamo backwards and downwards into position. T h e gears
can be f,elt to b,e meshing properly if the coupling is slightly oscillated as thc
dynamo is replaced, but d o not overdo th'e oscillations o r you may engage
the wrong teeth.
See that the bolts in the dynamo base are coinciding with the holes in the
dynamo platform, and th,en observe if the dynamo coupling yoke is exactl).
parallel t o the engine centre line. If it is not, withdraw the dynamo, reset
the coupling yoke and re-insert the dynamo. N o difficulty should be e x -
perienced in getting the dynamo in position with the correct teeth in mesh,
as the distance between one tooth and the next is sufficient to make an
appreciable difference to the position of the dynamo coupling yoke, a
difference which is immediately discernible.
Having satisfied yourself that the correct gear teeth are in mesh, replace
the screws in the dynamo base, taking particular care to tighten them up
evenly a partial turn at a time until all are uuite tight. Now m:~ke a final
test. T h e flywhe,el mark
1-4
should show exactly in the centre of the inspection
cover opening with the distributor rotating arm pointing towards No. 1
cylinder. (This can be readily found by tracing the high tension lead from
No.
1
sparking plug to its junction o n the distributor. Removal of the
distributor cover should show th'e distribcltor arm directly beneath it.) T h e
dynamo coupling bolt holes should be exactly fore and aft and at right angles
J / A .
PAGE FIFTY-FIVE