Classic/Antique Car Repair: !969 Cadillac Deville, hydraulic valve lifters, gm cars

Question
Are the lifters on the 472 engine adjustable ?

Answer
Cadillac has used hydraulic valve lifters since the mid 1930's. As such they are not adjustable. Some of the GM cars had adjusting screws on the rocker arms for an an initial centering adjustment. But Cadillac has no adjustment what so ever. If they are noisy then remove the valve cover and check for work rockers, bent push rods or worn rocker shafts.