They're 'bolted' down factory. No nut. No adjustment aside from the push rods or washers under the rockers to raise them which many do. Something like "raise it .050 for every .100 more lift over stock" 'pertaining to stock stem height* So with that thinking you'd raise the rockers .050 when using .100 longer valves then another .050 per hundred more lift if that were the case. -pertaining to stock rocker arms*