Oldsmobile 12537202 Chain Assembly, Timing

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To replace the timing chain on Chevrolet 305 and 350 engines, first, remove the chain tensioner and spring, followed by the camshaft gear with the chain attached. On all Chevrolet V8 engines, including the 305 and 350, the timing chain replacement procedure involves removing the crankcase front cover to access the timing chain. Crank the engine until the timing marks on both sprockets align closely and are in line between the shaft centers. Remove the three bolts securing the camshaft sprocket to the camshaft; this sprocket is a light press fit and will come off readily as it's also located by a dowel. The chain will come off with the camshaft sprocket. A gear puller is required to remove the crankshaft sprocket. Without disturbing the engine's position, mount the new crank sprocket on the shaft, then place the chain over the camshaft sprocket. Ensure the camshaft sprocket's timing marks align between the shaft centers, and the camshaft locating dowel fits into the dowel hole in the cam sprocket. Position the cam sprocket with the chain over it onto the camshaft and secure it with the three bolts. After installing the sprockets, turn the engine through two full revolutions to confirm the timing marks are correctly aligned between the shaft centers. For Oldsmobile 307, 350, and 403 engines, begin by removing the timing case cover and taking off the camshaft gear. The fuel pump operating cam is bolted to the front of the camshaft sprocket, and the sprocket is located on the camshaft using a dowel. Remove the oil slinger, timing chain, and the camshaft sprocket. If the crankshaft sprocket needs replacement, remove it as well, taking care to remove the crankshaft key before using a puller. If the key can't be removed, align the puller so it doesn't overlap the end of the key, as the keyway is only machined part of the way into the crankshaft gear. To install, reinstall the crankshaft sprocket, ensuring it starts with the keyway perfectly aligned, as correcting misalignment is challenging once the gear is on the shaft. Rotate the timing mark on the crankshaft gear to point toward the center of the camshaft. Place the timing gear over the camshaft gear and start the camshaft gear onto its shaft with the timing marks as close as possible and aligned between the shaft centers. Rotate the camshaft to align the shaft with the new gear and install the fuel pump eccentric with the flat side facing the rear. Drive the key in with a hammer until it bottoms and install the oil slinger. For Oldsmobile 263 Diesel Engines, when replacing the timing chain and gears, it's necessary to retime the engine's injection pump. Remove the front timing chain cover and valve covers, and evenly loosen all rocker arm pivot bolts to create lash between the rocker arms and valves, unless related service is being performed on them. Remove the crankshaft oil slinger and the camshaft sprocket bolt washer. Remove the timing chain, camshaft and crankshaft sprockets. If the crankshaft sprocket is tightly fitted on the crankshaft, use an appropriate puller to remove it. To install, reposition the crankshaft sprocket, ensuring the keyway is perfectly aligned, and rotate the crankshaft gear's timing mark to face the center of the camshaft. Mount the timing gear over the camshaft gear and ensure the timing marks align closely between the shaft centers. Rotate the camshaft to align it with the new gear. Install the fuel pump eccentric with the flat side towards the rear, drive the key in until it bottoms, and reinstall the oil slinger. The remaining installation steps are performed in reverse order, and it's essential to bleed down the valve lifters and check injection timing after completing the process.

When replacing the timing chain and gears on Oldsmobile 263 Diesel Engines, follow these steps:Remove the front timing chain cover and valve covers.Evenly loosen all rocker arm pivot bolts to create lash between the rocker arms and valves.Remove the crankshaft oil slinger and the camshaft sprocket bolt washer.Remove the timing chain, camshaft, and crankshaft sprockets.If the crankshaft sprocket is tightly fitted on the crankshaft, use an appropriate puller to remove it.To install, reposition the crankshaft sprocket, ensuring the keyway is perfectly aligned.Rotate the crankshaft gear's timing mark to face the center of the camshaft.Mount the timing gear over the camshaft gear and ensure the timing marks align closely between the shaft centers.Rotate the camshaft to align it with the new gear.Install the fuel pump eccentric with the flat side towards the rear.Drive the key in until it bottoms and reinstall the oil slinger.Complete the remaining installation steps in reverse order.Bleed down the valve lifters and check injection timing after completing the process.