Installing an Intake Manifold

Whether you’re changing the intake manifold to simply replace the gaskets or to change the performance of your ride, Mark Simpson demonstrates that with the proper planning the process can go smoothly every time. We’ll be installing a new Edelbrock Vortec intake manifold on a GM ZZ383 engine in our project 1935 Chevrolet Master Street Rod, and begin with thoroughly cleaning the cylinder head intake surfaces after the old manifold has been removed. All gasket material, RTV sealant, and oil residue must be removed without damaging the machined surfaces. Clean the intake bolt holes with compressed air and inspect the threads for damage. Simpson points out it’s best to install plugs in any unused ports before installing the intake manifold.

Position new Vortec-specific intake manifold gaskets on the cylinder heads, ensuring they are correctly aligned with the coolant passages and intake ports. Rather than using the factory-style end seals, apply a continuous 1/4-inch bead of high-quality RTV silicone across the front and rear block rails, extending the bead slightly up each cylinder head to prevent oil leaks.

With the help of another person if necessary, carefully lower the intake manifold straight onto the engine without disturbing the gaskets or RTV. Install all eight intake manifold bolts finger-tight. Because Vortec cylinder heads use a vertical bolt pattern, verify that the correct bolts and hardened washers are used.

Using a calibrated torque wrench, tighten the intake manifold bolts in the manufacturer's recommended crisscross sequence, beginning at the center and working outward in several stages until the final torque specification of 11 ft-lbs (132 in-lbs) is reached. Over-tightening can distort the manifold or damage the gaskets, so following the specified torque is critical. Note: Mark recommends taping any opening closed at this point to prevent any accidental debris from entering any of the open passages, then un-taping them as each component is installed.

Allow the RTV sealant to cure according to the manufacturer's recommendations before adding coolant. Reinstall the thermostat housing, distributor, carburetor, fuel lines, vacuum hoses, throttle linkage, and all electrical connections. Refill the cooling system, reconnect the battery, and carefully inspect for coolant, oil, or vacuum leaks during initial startup. Once the engine reaches operating temperature, verify ignition timing, idle quality, and carburetor adjustment. A properly installed intake manifold improves airflow, throttle response, and overall performance while providing years of reliable service on a high-performance ZZ383-powered street rod.