TIMING CASE AND DRIVE - K.7Adjust the valve clearances to 0.012 in (0,30mm) cold. Refit the rocker cover together with anew joint.7.Remove the engine from the dismantling standand refit to the application.TIMINGGeneralAs timing gears are employed on the 4.236 marineengine, the factory setting remains constant. Thefollowing information is given as a general guide duringan engine overhaul. It is well to remember that theremoval of the cylinder head in no way affects either thefuel pump or valve timing.Timing MarksWhen the engine is originally timed at the factory,certain marks are stamped on the gears, so that if forFig. K.14.Showing Timing Pin located in Crankshaft Pulley.any reason the engine timing has to be disturbed, thento reset to the original timing is quite straight forward.Timing PinA timing pin is fitted at the bottom of the timing casecover on the starboard side. When it is unscrewed itlocates in a hole machined in the rear face of thecrankshaft pulley, when Nos. 1 and 4 pistons are atT.D.C. (see Fig. K.14).Always return this pin. to its normal locationimmediately T.D.C. has been determined and before anyattempt is made to turn or start the engine.To Reset Engine to the Original TimingBefore commencing the retiming procedure it isassumed that (a) the camshaft, fuel pump and idlergears have all been removed, and (b) the camshaft isfree to turn by hand. (If the cylinder head assembly isstill in position, it is advisable to remove the atomisersand rocker shaft to facilitate the retiming operations).1.Turn the engine until the keyway in the front ofthe crankshaft is uppermost as shown in Fig.K.4. (This will bring Nos. 1 and 4 pistons toT.D.C.)2.Fit the camshaft gear by drawing it onto its shaftusing the retaining plate and setscrew. Lock thesetscrew with the tabwasher.3.Fit the fuel pump gear to the fuel pump driveshaft ensuring that the dowel is correctlylocated. Secure with the three setscrews andspring washers.4.Replace the idler gear as previously detailed sothat the timing marks are all correctly aligned asshown in Fig. K.4.5.Check that the backlash between the timinggears is within the limits quoted on Page B.8.NOTE: When the timing has been reset,great care should be exercised when firstturning the engine, for should the timing beincorrectly set, even by only one tooth, thereis the possibility that a valve head will strikethe piston crown.For Checking Fuel Pump Timing, see Page N.6Checking Valve TimingTo check the valve timing proceed as follows:1.Turn the crankshaft until the valves of No. 4cylinder are 'on overlap'.2.In this position set the valve clearance of No. 1inlet valve to 0.047 in (1,2 mm).3.Turn the engine slowly in the normal direction ofrotation until the clearance of No. 1 inlet valve isjust taken up. (In this condition it will just bepossible to rotate No. 1 inlet valve push rodbetween the thumb and the forefinger).
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