Engine knock 1948 Flathead V/8 59 A

[Ken/Alabama]

59A should have floating rod bearings so a spun bearing isn’t going to be your problem. The only way you’re going to know what the issue is is to pull the pan and remove the bearing that serves the front two rods. Carefully measure the crankshaft journal for wear . If it’s with specs you’ll need to remove the pistons and rods and have the rods checked to be sure they’re in spec before just replacing the bearing.

[L-head]

A 59A engine could have an 8BA or Merc crank in it if it has been "worked on." It could have the late model rods and rod brgs. The pan needs to come off. Better safe than sorry.