ENGINE INSTALLATION INSTRUCTIONS PART NO 3931601 CONT GENERAL INFORMATION CONT 3 When using on powerglide models remove clutch pilot bushing from crankshaft 4 The intake manifold of this engine is equipped with a vacuum fitting for the crankcase ventilation sys tem If desired this vacuum can be used on past models by removing the dust seal and installing connector Part No 3859374 transferring the hose and clamp from the outboard fitting to the connector IMPORTANT If the above source of vacuum is not used plug the opening with 3 8 inch clup plug Part No 838323 If converting to use the added source of vacuum plug previously used opening with pipe plug Part No 9420756 If above is used on vehicles equipped with vacuum power brakes seal previously used source of ventilator vacuum by pinching and soldering tube to prevent leakage 5 Models with optional equipment require transfer or replacement of engine parts special to such options 6 This cylinder block assembly has a composite cylinder and case with two 2 machined oil level gauge bosses A special pin Part No 3848405 is included with this assembly for the purpose ofplugging the oil level gauge tube hole not applicable to the installation 7 This engine is equipped with an aluminum camshaft gear An undesirable noise level may develop when using the aluminum camshaft gear on passenger models It is therefore recommended that the aluminum gear be removed and replaced with the gear from the replaced engine if in usable condition or purchase new bakelite gear 8 A plug is provided in the cylinder head temperature switch hole for models prior to 1967 For 1967 model remove plug to insert temperature switch 9 On closed ventilation modelslremove the center portion of the grommet on the rocker cover in order to assemble the hoses and pipes 10 The crankcase front end cover provided with this assembly does not require the four 4 front attached bolts When transferring the oil pan assembly and maintaining this cover the use of oil pan gasket unit 39309621 is required The four 4 attaching bolts can be discarded wi T i 197O CHEVROLET MOTOR DIVISION GENERAL MOTORS CORPORATlON P A 31S 74