PISTONS AND CONNECTING RODS-F.S The gaps of the remaining rings should be stag- gered alternately along the gudgeon pin axis. Liberally lubricate the rings in their grooves and see that they can move freely in their locations, this does not apply to the laminated type in the fourth groove, which if correctly fitted should not move freely due to the outward pressure of the top and bottom segments on the ring groove walls. When all the rings have been fitted, they should be shown in Fig. F.9. Always ensure that internally stepped or taper faced rings are correctly fitted. They are marked TOP or BTM (bottom) to ensure correct replacement.
The top compression and slotted oil control rings may be fitted either way up. F11 Spring loaded Scraper Ring 7. Fit the two connecting rod securing setscrews and tighten evenly to the torque quoted on Page B.2. NOTE: Locking tabs are not fitted to these set- screws. 8. Repeat this procedure for No. 4 piston and con- necting rod assembly. 9. Rotate the crankshaft to bring numbers 2 and 3 crankpins to bottom dead centre. 10. Repeat procedures 2 - 7 to fit the two remaining assemblies. 11. Refit the lubricating oil sump. (Refer Page L.4). 12. Refit the cylinder head assembly. (Refer Page E.7). When fitting the chrome plated spring loaded scraper ring. (see Fig. F.1 0).
the following procedure should be adopted:- 1. Fit internal expander (1). 2. Fit two rail rings (2) at the bottom of the groove. 3. Fit spiral ring (3). 4. Fit two top rail rings (2). When fitting rail rings, the gaps should be staggered. To Fit Piston and Connecting Rod Assemblies Fitting New Pistons Before fitting the piston and connecting rod assemblies to their respective cylinder bores, thoroughly clean and liberally coat each bore with clean engine oil. 1. Turn the engine until the crankpins of numbers 1 and 4 cylinders are at the bottom dead centre. 2. Using a suitable ring clamp of the type shown in Fig. F.11, carefully compress the rings of No. 1 piston and hold in this position. 3.
With the word 'FRONT' on the connecting rod facing the front ot the engine, insert the rod care- fully into No.1 cylinder bore. NOTE: The cylinders are numbered 1, 2, 3, 4 starting from the front (water pump) end of the engine. It is extremely important that these com- ponents (marked as shown in Figs. F.4 and F.5), are returned to their original locations. 4. The piston head may be gently tapped with the shaft of a hammer as shown in Fig. F.11 until all the rings have entered the cylinder bore. 5. Draw the rod towards the crankpin, place the top half bearing shell in position locating the tag in the machined slot and liberally oil, draw the rod onto the crankpin. 6.
Fit the lower half bearing shell to the connecting rod cap, locating the tag in the machined slot, liberally oil and fit the cap to the crankpin, ensur- ing that the numbers on the rod and cap coincide as shown in Fig. F.4. With new 4.108 and 4.107 pistons a machining allow- ance is provided on the crown of the piston to enable the necessary material to be removed by means of a lathe so that when fitted the piston height above the cylinder block top face will be within the limits quoted on Page B.3.
To determine the exact amount to be removed from the piston crown, the piston, connecting rod and bear- ing assembly will have to be fitted to its respective cylinder bore as previously described, and the piston height above the cylinder block top face measured with the particular piston at top dead centre. This piston height can be measured by means of a piston height gauge of the type shown in Fig. F.12. Repeat for each new piston to be fitted and mark each piston with the number of the cylinder bore it will belong to, (not on the top as any marking here will be removed by the machining).
When each piston has been skimmed it should be checked again when finally re- fitted to ensure that any new piston fitted is now within the limits quoted. Once the piston height is correct mark any such piston on the crown with the number of its respective bore. (Refer to Fig. F.5). Pretopped pistons are available for fitting to 4.108 vehicle engines and all 4.99 engines and are available in three grades (see separate tables). For identification purposes, the grade letter is stamped on the piston crown.