PISTONS AND CONNECTING RODS-F.2 !nspection 1. Examine the pistons for scoring and any signs of groove damage. 2. Check the clearance of the piston rings in their respective grooves by placing the ring outer face into the groove and a suitable sized feeler between the ring and groove face. NOTE: All ring gaps, ring groove clearances etc., are given in the Technical Data Section on Page B.4. 3. Check the fitted gaps of the piston rings, bearing in mind that in worn cylinder bores these gaps should be checked at the bottom of the bore. 4. Check the fit of the gudgeon pin in the small end bush, if excessive, replace the small end bush. 5.
To renew the small end bush, remove the old one by means of a suitable press and 'dolly'. Press in the new bush, ensuring that the oil holes coincide when fitted. Ream out the new bush to suit the gudgeon pin, then check the rod for parallelism and twist. (Refer Page B.5). 6. Examine the big end bearing shells for any signs of wear or pitting. To Refit the Pistons to the Connecting Rods If the original pistons are to be refitted they must be re-assembled to the same connecting rods, i.e. No. 1 piston to No.1 connecting rod assembly. Refer to Figs. F.4 and F.5 for location of piston and rod numbering. Any new components fitted should be numbered the same as those which they replace. F4 Note:
Where controlled expansion pistons are fitted, these have a 0.020 in (0,51 mm) off-set gudgeon pin towards the camshaft side of the engine and when replacing these pistons, they must be fitted the correct way round, i.e., the word "FRONT" or arrow on the piston crown to the front of the engine. If these marks have been removed by machining the crown, then the small round recess in the gudgeon pin bore 'A' Fig. F.6, must face the front of the engine. Where controlled expansion pistons with off-set pins are fitted, the latest phosphated crankshaft pulley setscrew must be used. 2. Place No. 1 piston onto its head, noting the posi- tion of the mark previously made to indicate the "FRONT". 3.
Hold No. 1 connecting rod with the small end between the gudgeon pin bores so that the word "FRONT" cast on the rod is towards the same side. 4. Push the gudgeon pin into the piston thus locating the connecting rod in position. 5. Fit the two retaining circlips ensuring that they locate correctly in their recesses. (Refer to Fig. F.7). NOTE: If the engine has been in service for some considerable time it is advisable to fit new circlips, even if the old ones do not appear to be strained or damaged. 6. Repeat this procedure for the three remaining pistons and connecting rods. 1.
Warm the piston in a suitable clean liquid to a temperature of 100 - 120'F (40 - 50"C) which will enable the gudgeon pin to be easily pushed into the piston bore when the piston and rod have been correctly aligned F5