Engine Notes

1968 BUICK 350" V8 ENGINE REAR MAIN BEARING SEAL INSTALLATION NOTE - This engine has laminated neoprene asbestos composition seals installed in grooves in sides of rear main bearing cap. Due to variations, groove in bearing cap could be oversize. To insure proper sealing, dip seals in penetrating oil or kerosene and install immediately. This will cause seal to swell, sealing any oversize condition.

1968 BUICK 350", 400" & 430" V8 ENGINES CYLINDER HEAD GASKET INSTALLATION & GASKET REPLACEMENT CAUTION: On these engines with series code PD-600, 700, 800 or 900, a.045" composition head gasket was installed on both banks. Composition gaskets must be used for replacement on these engines. Head bolts must be torqued to 80 ft. lbs. (350"), 115 ft. lbs. (400" & 430") in sequence shown.

NOTE: When replacing steel head gasket on these engines, to correct a coolant leak, install composition gasket, Part No. 1385204 (350"), No. 1384094 (400" & 430"). Replace only the leaking gasket, it is not necessary to replace both gaskets.

Fig 1: Buick V8 Engines Cylinder Head Tightening Sequence (Composition Gasket)

Courtesy of GENERAL MOTORS COMPANY

1969 BUICK 350", 400 & 430" ENGINES IN HEAVY DUTY OPERATION OIL PRESSURE CHANGE: Engines used for sustained high speeds, trailer towing, police use, etc., should have new oil pump relief valve spring (Part No. 1233892) installed. Spring raises oil pressure from 50 psi to 60 psi. Manufacturer advises that increased oil viscosity is necessary to maintain adequate engine oil pressure at high engine operating temperatures due to heavy duty service.

1970-77 BUICK-ALL MODELS SEMI-CLOSED ENGINE COOLING SYSTEM: Coolant is checked and added to a separate reservoir bottle (at operating temperature) and not at the radiator. However, if a quantity of coolant is needed, coolant should be added directly to the radiator to insure system is filled.