....so if I need rockers and studs...why would I NOT go 7/16? Looking at the Comp Ultra Golds, and the price is the same. Are there clearance issue? I shouldn't "need" 7/16...but I mean....why not, right?

 

Stock press in studs are only 3/8s. You would have to drill, mill and tap the heads for larger studs.

 

BBC screw in rocker studs are 7/16" on the top and 7/16" on the bottom. SBC are generally 3/8-3/8. When switching to a larger stud, the threaded hole in the SBC head doesn't change so even though the top of the stud is 7/16", it's still held onto the head with a 3/8". If your current heads do not have screw in studs then switching to a 7/16" rocker is still going to cost you more money because of all the extra machine work required.

Advantage of a 7/16" stud is with very heavy spring pressures. The 7/16" stud will flex a lot less than a 3/8" stud. If you're not using double or triple valve springs that have over 600 pounds of open force then a 3/8" stud is fine.

My BBC triple valve springs are well over 800 pounds pressure when open. I stopped using stud mounted rockers and now use shaft mounted rockers. I was using a stud girdle with the stud mounted rockers to eliminate stud flexing but wanted to use lower valve covers. The girdle on top of the rocker means needing very tall valve covers. The shaft mounted rockers work wonderful and they're as low as regular rockers but I don't think you would like to see the price of T&D rockers.

 

I have a set of RHS pro action heads, and I don't have studs or rockers. ...but still......7/16 may be way overkill.

 

[When switching to a larger stud, the threaded hole in the SBC head doesn't change so even though the top of the stud is 7/16", it's still held onto the head with a 3/8".]

Not true on most after market heads with screw in studs.
I always use 7/16th.

 

The SBC uses a 7/16-14 thread in the head for all screw in rocker studs.

The top threads or rocker portion is a 3/8" or 7/16"

If you have to buy rocker arms, and studs then make the move over to 7/16" rocker studs.

 

Not overkill at all. More valvetrain stability is always a nice ins policy.

 

If you're buying new rockers and will run guideplates, it's a no-brainer to go with 7/16".
As Night said, factory and aftermarket SBC heads with screw-in studs will have the 7/16-14 thread in the stud boss. Only the top of the stud varies between 3/8 and 7/16.
IMO, the only reason you would want 3/8 is if you want to run self-aligning rockers rather than guideplates. I'm not aware of any SA rockers available in 7/16.
The top of the stud is what flexes above the hex wrenching "nut", never the bottom EVEN IF it were only 3/8.
This is a case where bigger is better, no downside. And not just for SR cams and huge spring pressure either. Valvetrain stability not only adds durability, but power as well, even on little bitty SBC HR setups like my 7100 rpm LT1

 

Agreed- if you are buying rockers and studs anyway there is no reason to stick with the smaller 3/8" (stock) size. Go up to 7/16". They're stronger and they probably keep the valvetrain more accurate and stable at higher RPMs.

If I'm running a solid lifter cam I almost always use the larger 7/16" studs and rockers.

 

Yep, even the mildest SR springs would require that.
If I were to step up to a SR cam, it would be stout enough where shaft rockers would be the prudent option.