A neat trick GM did on my 37 Buick was to coat the inside of the rocker cover with about 1/4" of very dense asphalt like substance plus add a 1/2" felt pad on top the rockers. I guess Buick's weren't supposed to click away like chevies. I say GM did it because I've had two 37's and both were like this. With the cover off they sound the same only the Buick has two more sets of rockers to click away.
A Noisy Valve Is A HAPPY Valve ! Harley-Davidson " PanHead " engines also had this feature.... Unless your rocker shafts are all worn out , it should sound like a well oiled sewing machine , like Grammaw's old Singer .
My old 51 I used for hunting back in the late 60s got real quiet when I stuffed fiberglass insulation under the dash and under the seat and behind the seat. My mother drove an LTD then and my old truck ( old at only 17 yrs ) was every bit as quiet as that LTD.
