Remove the cable from the negative terminal on the battery if at all the unit has an anti theft code then make sure you have the correct entry code for the radio. Sit the number six piston on the Top Dead Center (TDC) on the compression stroke by first positioning the No. 1 piston at TDC, followed by a 360 degree rotation of the crankshaft. Pull off the radiator and for certain models, unscrew the compressor and put it aside but don't discharge the AC lines. For the models with carburetor should eliminate the fuel pump. The components that need to be removed include the distributor, and labeling the rotor and the position of the base before their removal, the valve cover, the rocker arm assembly, the push rods, the valve lifters, and the timing gear cover. Inspect the timing gear backlash and adjust/replace the crankshaft and camshaft gears if the timing is off. Disconnect the thrust washer bolts on the engine block, and ease out the camshaft across the bearings while supporting it near the block. Check the gap of the thrust plate using a feeler gauge and if the gap is large then replace the thrust plate. If needed, unclip the snap-ring and push off the camshaft timing gear, or hand over it to a machine shop in case of absence of a press. Take out the crankshaft pulley key, and pull off the crankshaft gear with the aid of a puller. All exterior and interior surfaces must be clean, and the gears and other components have to be checked for wear and signs of damage; timing gears should be changed in pairs. Position a timing gear outward, match the 'mark' with the crankshaft 'key', and the 'key groove' should be upwards. Before the installation of the camshaft it is important to lubricate the camshaft bearing journals and lobes and then place the camera shaft on the engine block without scratching the bearings. Push the camshaft gear over the crankshaft gear to match the 'zero' indicators on your timer. Replace the screws of thrust washer by varying the torque of the washer bolts then fit the crankshaft pulley key. Should it be removed, reintroduce the oil nozzle with the hole facing the gears whilst also being clean. Intially, reinstall the other components in the reverse order, and in the case of reusing the original camshaft and lifters, ensure they are fitted back in the original positions if not then new lifters should be fitted in case a new cam shaft is fitted. Check for leakage and unusual sound then add the coolant,change the oil and oil filter if necessary then start the engine and check for the ignation timing.