A "valve train very slight adjustment" will not propagate to specific plugs and more random ,the number.
If the "very slight adjustment" fouled the plugs that bad and that fast, his push rods would have fallen out or bent. A slight adjustment would not foul the plugs and you would have definitely heard a noise where the valve lash would have needed attention.
The motor was professionally built correct?
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
