Measuring Timing Chain Stretch

Check timing chain and sprocket for wear. If either side has excessive wear, replace timing chains, sprockets, guide shoes and tensions for both sides.
1. Remove valve head cover, refer to Valve Cover/Service and Repair. Service and Repair

Fig. 5 Timing Chain Gap:

Fig. 6 Travel Of Tensioner Plunger:

2. Pull up on top of timing chain Fig. 5. This produces a gap between the bottom of the timing chain and the bottom area between two sprocket teeth. A maximum clearance of .067 inch must be maintained. A gap of .067 inch corresponds to a travel of .866 inch by the timing chain tensioner plunger Fig. 6.

Fig. 7 Use Of Drill Bit As Gauge:

3. Insert the solid end of a number 51 drill bit (.067 inch diameter) to gauge size of gap Fig. 7. If drill bit does not fit into gap, wear is not excessive and components can be reused. If drill bit fits into gap between timing chain and sprocket teeth the following components must be replaced: timing chain shoes, tensioners, guides, sprockets and tensioner shoes.