Re: 1947 356 valve clearance

Posted by HH56 On 2024/4/23 14:18:54

I don't find those particular numbers in Packard literature unless they were published as a later service change from the original specs and one followup change in a service counselor which I did find. Those specs were for mechanical lifters though.

As was mentioned, the 356 has hydraulic lifters so 0 clearance during operation. The only 356 spec I see is used during initial valve installation when substituting the plug tool in place of the hydraulic lifters. That spec is used when setting the maximum length of the stem if installing new valves or even after a seat regrind and remained unchanged on all years of the 356 at between .030 and .070. As I understand it that clearance is to ensure when the lifter is pumped up it is kept in the optimal working range and valve can still close.

Original spec for mechanical lifters was .007 on intake and .010 on exhaust which was later reduced to .006 and .008 to cut down on noise. With expansion to contend with it would seem to me the Motors specs would be a bit tight..