Piston Rings - MG MGA Twin Cam Workshop Manual

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Fig. A.12 A connecting rod bearing. Note the bearing locating tab
Dismantling
Remove the two circlips securing each gudgeon pin in its piston and press the gudgeon pin out. Mark
the gudgeon pins and pistons for reassembly to their original positions and to their original connecting
rods.
Check the gudgeon pin and the connecting rod little end bearings for wear with the dimension given in
the "GENERAL DATA' section. If the bush is worn it should be removed and a new bush fitted, A light
press is most suitable for this operation.
Reassembly
When pressing in the new bush ensure that the oil hole in the bush is in line with the oil hole in the
connecting rod.
Replacement bushes must be finish-reamed to size after pressing into the connecting rod (see the
'GENERAL DATA' section for the correct dimensions). The piston gudgeon pin bosses must not be
reamed as oversize gudgeon pins are not supplied.
Assemble the pistons to the connecting rods by inserting the gudgeon pins, which should be a hard
hand-push fit at a room temperature of 68° F. (20° C.). Secure each gudgeon pin in position with the
two circlips, ensuring that they fit well into their grooves.
Replacement
Replacement of the piston and connecting rod is a direct reversal of the above, but the piston ring
gaps should be set at 180° to each other.
If the piston rings have been removed from the piston they must be replaced as detailed in Section
A.28.
It is essential that the connecting rod and piston assemblies should be replaced in their own bores
and fitted the same way around, i.e. with the big-end cap facing the half-speed shaft side of the
engine.
Refit the big-end bearings in their original positions.
A.28 PISTON RINGS
If no special piston ring expander is available use a piece of thin steel such as a smoothly ground
hacksaw blade or a disused .020 in. (-50 mm.) feeler gauge.
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