Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.