In my 1936-1942 Plymouth service manual: Tighten all cap screws (bolts) or nuts in the sequence shown, drawing all cap screws or nuts down evenly, repeating until they are tight. A final tightening should be made on engines with cast iron heads when the engine has been run sufficiently long to bring all parts to operating temperature. For engines with aluminum heads, check the tension after the engine has been run and cooled and while it is still cool. Using a torque wrench, tighten cap screws to 65-70 foot pounds, nuts to 55-60 foot pounds. Hopefully you have a service manual to confirm this, also, to show the sequence, which is critical.