no - with typical performance cams. - Super high lift cam - different story. Kif it makes a difference to you, full roller rockers will not fit under stock valve covers, but roller tipped rockers will.
What i am doing is racing the car on a circle track. Rpms are 6200 cam lift is only .425 at valve i have a set of tall valve covers i used on a set of world product heads i am changing engines and wanted to be able to just change rockers not the heads. Just to leave the engines together.
FYI, its not true that full roller rockers wont fit under stock valve covers. i have a set of comp pro magnum rollers, 7/16 studs, and a cam w/ .610 gross lift, and i'm running the factory z28 style valve covers. i did have to grind off the factory oil drippers in the valve covers, but that was just a slight interference. a valve girdle would obviously cause a problem, but as of yet i have not needed one. in the future i likely will run a set of jesel shaft mount retrofit rockers if i have any valve train stability problems, and they too should fit under a factory valve cover. what can i say, i like to look stock and carry a big stick
Chicayne67 - The TFS heads have a raised valve cover rail, so you gain clearance just by using the TFS heads whether you use factory valve covers or not.
I agree with 68RS406, they are not really that much taller than stock stamped rockers. IMO You especially want to watch for interference on AFTERMARKET CAST ALUMINUM valve covers because they have thicker side walls and could hit on the side by the push rods.
You dont really want the cheap rockers either. Like the summits or the proform. I think eric has energizers and he said 20000 miles tops, I have heard the gold/ pro magums or the H-sharp ones are good. I guess a race motor is lucky to see 5000 so energizers should be fine.