My 77 highboy has a 351M, and it has a slight valve clatter nothing serious just annoying. I checked the torque on all rocker studs and they are good and the push rods don't have any play. Could it be worn out lifters? Or do 351M always have a little noise. My Dad's 78 Bronco is having the same problem with his 351.
Any help is appreciated, Thanks

1977 F-250 Highboy, 351M, NP435, NP205, 44 6CF front, 60 HD outback, hydro-assist, custom front bumper, 33x12.5x16.5 Mudrovers