K-F manifolds are prone to crack if not properly installed.  Use only hardened brass nuts on ALL manifold studs - do not use steel - and tighten only to spec torque.  This includes manifold mating studs, exhaust pipe studs, carburetor studs and engine manifold studs.  Do not use lock washers, use only flat washers.  Use new gaskets only, do not re-use old gaskets.  The following instructions have worked well for us but we cannot guarantee your manifold will not crack even if these steps are followed.  Refer to the appropriate year K-F Factory Service Manual for additional information.

When installing manifold be sure to follow these steps:

1. Fasten intake and exhaust manifold together and run hardened brass nuts up just enough to secure the units tightly together.  Do not compress gasket  - do not torque at this time.

2. Install manifold onto engine using factory-type retainer rings (thick special washers) and hardened brass nuts.  Run nuts up sufficiently to secure manifold tightly to engine without compressing gasket - do not torque at this time.

3. Tighten mating nuts that hold the intake and exhaust manifolds together to proper torque (18 to 23 foot pounds per manual), we suggest no more than 12 to 18 foot pounds.

4. Tighten manifold to engine nuts to proper torque (30 to 35 foot pounds per manual), we suggest no more  25 to 30 foot pounds.

Failure to follow these steps may result in a cracked manifold after being heated to operating temperature and normal cool-down.

5. Re-torque all nuts after 2 operating hours and a complete cool-down.