Just purchased a 1940 Lincoln Zephyr. I noticed a distinct light knocking in the engine. I contacted the machine shop that performed a 6.6K rebuild for the previous owner, only 4K miles ago. I discovered the hydrolic lifters were converted to solid adjustable, he did not have very much additional information on the rebuild. This weekend I pulled the Edmunds Custom intake and took a look, nothing broken, one of the solid lifter adjusters was very loose and far too easy to adjust, I plan to use green locktite to resolve, recommendation from other post. I adjusted the lifters to intake .010-