Re: ‘56 400 vapor lock

Posted by HH56 On 2022/5/22 10:40:43
They do get stuck on occasion but if you are able to grasp the weight and rotate the flapper assy that part is OK. Do take care not to use a great amount of force and on the 55-6 assys I would avoid hitting the assy with a hammer. If the movement is stiff do not try to lube with ordinary petroleum products as oil or grease will degrade from the heat and make the problem worse. Here is a procedure Packard recommended to lube earlier valves. The valve layout is different but the principle will be the same. There may be a commercial product that is graphite based and will effectively be the same as the kerosene and graphite.


55-6 valves are contained in a small cast cylindrical assy that is held in position by casting flanges that fit into respective openings in the manifold and exhaust pipe. Those flanges along with gaskets and the exhaust pipe attaching bolts that fit in sort of semicircular depressions in the cast assy provide a solid leak proof section. Aftermarket replacements from a parts store that fit the Packard manifold and mounting method have proven hard to find but NOS are still available from some of our vendors at a significantly higher price.

The original assy valve position flanges are prone to cracking or breaking off so do be gentle with the assy so as not to do damage. If enough flange is broken it will no longer stay in position and vibration can move it enough the missing flange parts will provide a good spot for an exhaust leak.

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