SUBJECT: Camshaft End Float Restraint

MODEL: All 'D' Engine Equipped Vehicles
 

Since the introduction of the 'D' series 'Hemi' engine,  there have been occasional reports received of a 'clunking' noise emanating from the camshaft/timing cover area.  This noise is normally only evident at engine idle speed on engines that have covered relatively high kilometreage,  and in most instances disappears immediately the engine R.P.M. is increased.. 

This condition does not detrimentally affect the in-service operation of the engine,  however there remains the need to eliminate this undesirable noise in order to retain owner confidence in the durability of the engine. 

The referred to noise is usually due to axial end float 'cycling' of the camshaft,  causing the camshaft sprocket and/or timing chain link pins to strike the front of the engine block.  Immediately engine speed is increased,  oil pressure delivered to the rear main bearing area of the camshaft forces the camshaft forward, thus preventing the camshaft sprocket from striking the front of the engine block. 

In order to correct this condition at minimum cost from an owner point of view,  the following rework procedure is recommended: 
 
 

1.	Remove radiator,  fan,  vibration damper and timing cover.
2.	Locate on the timing cover the centreline of the camshaft.  (Refer to figure 1.)
	Figure 1.
3.	Drill a 5/16" hole through the timing cover to align with the centreline of the camshaft.  Braze a 5/16 U.N.F. nut to the outer side of the timing cover  (it is recommended that a 5/16" U.N.F. bolt and nut be used to positively locate the nut being brazed to the outer side in the timing cover,  to ensure correct alignment with the centreline of the camshaft.)
4.	Modify a 5/16" x 2" U.N.F. setscrew,  by drilling the centre of the bolt sufficiently to accommodate a 1/4" diameter steel ball bearing.  (Refer to figure 2.)
	Figure 2.
5.	Refit timing cover to engine.
6.	Screw lock nut (5/16" U.N.F.) over full length of setscrew,  then thread setscrew with ball bearing positioned (smeared with grease to temporarily secure) through nut brazed to timing cover.  Ensure steel ball bearing does not dislodge from counter bored setscrew.
7.	Adjust setscrew to eliminate end float of camshaft,  then back off 1/4 turn.  Lock up setscrew with lock nut.  (Refer to figure 3 for assembly condition).
	Figure 3.
8.	Refit vibration damper,  fan and radiator,  refill cooling system.
9.	Road test vehicle, ensure there are no oil or cooling system leaks.  IMPORTANT:  Ensure that the end float adjustment screw is backed off 1/4 turn minimum,  and that there is sufficient clearance between setscrew and fan belt.