Rocker arms for 408 build

Hughes take on this issue.
Note that .580 is referring to the stud, not the stock rocker.

#2---Magnum & LA Heads

We believe the 5/16" stud is strong enough for all hydraulic roller cam with lifts up to 0.580". The heads can be removed, drilled and tapped for the larger studs. Here again you will need one with a thinner hex to clear the rocker as mentioned previously; we'll have them when you need them, part number 7601(call). If you are running a flat tappet or a solid roller cam with more than 0.600" lift we suggest a stud girdle P/N JPP 1194. We don't think the practice of installing 7/16" studs is a safe modification. Look at the boss for the exhaust studs, even the reinforced ones on the R/T heads. We are not comfortable with putting a stud that size in a boss that small. It won't strip out; it may just break off causing you to have to start over with a new head. The stud girdle can be used with the 5/16" bottom stud set-up too because it is 3/8" on top. The stud girdle will allow will you to run any spring pressure you want.