they don't have lifters.
sitting atop the valve stems is a cam follower, shaped like the cap on an aerosol can, only smaller.
its upside down, the opening faces down, it goes over the spring. the cam lobes ride on the "bottom" of the cam. the cam followers come with differing thickness' of the bottom plates. you replace the follower with one of a different thickness to adjust the "valves", actually the gap between the cam lobe and the follower.
the camshaft has to be removed to access the cam followers.
adjustment procedure is to measure the existing gap, then remove cam and follower, measure thickness of existing follower, then calculate the required thickness. then go buy new follower of correct thickness. these are purely mechanical, no hydraulics.
I have 338,000 miles on my 2005 2.3 Duratec. have not touched the valves yet.
if there was a valve grind done on it, all the followers should have been replaced because the gaps would have gotten smaller.
maybe the pistons are hitting the valves as the metal expands. that's not a good thing.
are you sure the noise isn't the intake flapper?
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