Reply to "Robert Shaw 333-180 Source?"

Nothing new on the subject, the factory that manufactures the thermostats is shut-down for retooling. The 333-180 is out of stock. Production is supposed to resume in March or April (I forget which).

The 351C was designed to employ a Robertshaw high-flow thermostat as standard equipment and it incorporates a unique high-flow warm-up system Ford called a controlled by-pass system. A high volume of coolant was recirculated within the block (bypassing the radiator) during warm-up. This high flow bypass system prevented the formation of hot spots in the cylinder heads while warming the motor to operating temperature more quickly and more evenly.

Diverting a high volume of coolant away from the radiator would lead to over-heating during normal vehicle operation, so coolant recirculation was controlled (shut-off) once the motor reached operating temperature. This was accomplished via a unique 11/16” OD copper “button” on the bottom of the Robertshaw thermostat which extended downward as the thermostat opened and plugged an orifice in a brass plate mounted inside the block immediately below the thermostat. This button is what is missing from the generic Robertshaw thermostat designed for small block Fords, Chevys and Mopars in your link.

The high flow warm-up and controlled bypass aspects of the 351C cooling system were advanced designs for their day, and cannot be improved upon even today. But this unique design makes it imperative to locate and use the proper thermostat, which is unique to the 351 Cleveland engine series. The cooling systems of modern motors have similar functionality, but it is accomplished with a "divorced" thermostat, one that is mounted externally from the engine block. The 351C was unique in accomplishing this functionality internally ... and it was made with only a small modification of the standard Robertshaw thermostat. Unfortunately that small modification became a major stumbling block.

My advice is to use the 333-192 thermostat which IS available.

-G