When searching for the torque specifications for the bolts on intake manifolds, it is necessary to find the specs for the exact make and model rather than simply the model year. The torque specs for bolts are highly individualized. Since most manufacturers use different bolts for different engines, the specs for bolts on one intake manifold will rarely correspond to those of another intake manifold. Relying on inaccurate or imprecise torque specs can lead to serious problems. Not tightening a bolt enough can fail to ensure the proper seal, and tightening a bolt too much can cause it to break, either immediately or during times of increased stress.
An intake manifold is a primary part of the fuel-induction system and serves as the conduit between the carburetor and the ports in the cylinder head. Manifolds come in several types and designs. For instance, Edelbrock manufacturers and sells eight series of aluminum intake manifolds for various engine types. Ensuring that the airflow specs of the intake manifold match the requirements of the camshaft, cylinder and engine helps to guarantee peak performance, and making certain that the bolts on the intake manifold are tightened to the right torque specs helps create the necessary air pressure.
Torque is basically the amount of force applied to an object in order to twist or turn it. It is usually given in foot-pounds or inch-pounds, with one foot-pound equivalent to one pound of force applied to the end of a lever (such as a wrench) that is 1 foot long. Bolt torque specs for vehicle maintenance are often based on the bolts being clean or perhaps even lightly lubricated with clean motor oil. It is common to tighten the bolts on engine components in separate cycles. Tightening all the bolts to a given torque, and then returning to the first bolt and tightening each of them to a second, and then perhaps even a third, specification.
Here are some examples of bolt-torque specs for 1997 intake manifolds. These specs should not be applied to any intake manifolds other than the ones cited. For the intake manifold of the 1997 Ford Mustang 3.8-liter engine, first tighten each bolt to 96 inch-lbs of torque, then tighten each bolt to 15 ft-lbs and, finally, tighten each bolt to 24 ft-lbs. For the intake manifold on the 1997 Chevrolet Corvette 5.7-liter engine, tighten each bolt to 44 inch-lbs and then go back and tighten each bolt to 89 inch-lbs. For the 1997 Pontiac Firebird 5.7-liter engine, tighten each bolt to 44 inch-lbs and then go back and tighten each bolt to 7.5 ft-lbs.
