1952

When working on intake and exhaust manifolds it must be understood that both manifolds must be attached to the valve body and to the cylinder head in such manner that slippage can take place at the joints to compensate for differences in rate of expansion and contraction of the several parts due to heat. This is necissary because the parts do not have the same temperature under all operating conditions.

The assembly and method of attachment of these parts have been designed to avoid leakage of joints while permitting the required slippage. If attaching bolts and nuts are not tightened in proper sequence or are tightened excessively, warpage, leaking joints or cracked manifolds will result.

When Leakage occurs at a manifold joint the condition can usually be corrected by proper adjustment of bolts and stud nuts without removing or replacing parts. Do not attempt correction by simply tightening bolts or nuts at pint of leakage. Instead, loosen all manifold to valve body and cylinder head bolts and nuts, allow parts to cool to shop temperature, then tighten bolts and nuts to specified torque in the sequence given in step 5 below.

The folllowing assembly and installation procedure should be used when replacing either manifold or the valve body. Manifolds should never be removed while engine is hot because warpage is liable to occur.

1. On Series 40-50, install the valve body on the exhaust manifold with a new ring gasket in pilt ring recess in body and a new gasket between body and manifold; make sure that pilot ring is in place. See figure 3-11. Leave attaching stud nuts snug but not tight.
   
2. Coat joint surfaces with graphite lubricant, then install intake manifold on exhaust manifold valve body leaving attaching bolts snug but not tight.
3. Install intake and exhaust manifold assembly on engine with new intake manifold gaskets. The individual intake manifold gaskets are centered and the branches of the intake manifold are aligned with the intake prots in cylinder head by pilot rings installed at each joint.
4. Exhaust manifold gaskets are not used. In production, a special compoind is used at joints between manifold and cylinder head, and original manifold may be reinstalled without using additional compound. When a new manifold is installed, however, coat the joint surfaces with a thin fluid mixture of graphite and oil.
5. Tighten bolts and nuts in the following sequence, using a torque wrench;avoid excessive tightening.
   1. Tighten manifold to cylinder head stud nuts to 25-30 ft. lbs. torque.
   2. Tighten exhaust manifold to valve body stud nuts to 25-30 ft. lbs. torque.
   3. Tighten intake manifold to valve body bolts to 15-20 ft. lbs. torque.