356 exhuaust valve guides

Posted by Bill Butterworth On 2013/4/22 10:16:04

Anyone have information on the reason the top .400" of the guides were relieved to 3/8" in the 40 through 47 and not in the 48-50 356 engines. This has something to do with sticking exhaust valves but why then did Packard go back to non relieved guides in the 48-50 356 engines? Did other Packard engines also have this change?