[WYT VNM]

Adjustable rockers will allow you to more precisely set the "preload" on the lifter......especially if there has been any machine work to the heads or block. With 35 year old stuff, mixed with new lifters, cam etc., non-adjustables require close attention to the pushrod length. It is my understanding that adjustables have a higher lift ratio than non at 1.73??? When if you change to ball/cup pushrods, make sure the new ones clear the passage thru the intake.