3/8” or 7/16” rocker studs?

[travis]

At what point do you “need” the bigger studs? What dictates this...rpm, spring pressure, or ???

[n2xlr8n]

...Lobe design, etc.

I've always looked at it like if the application would allow 7/16", that's what I used.

Having dropped a few valves in my younger years, I prefer stable valvetrain.

[sanfordandson]

Bigger is never worse in this case. 7/16 all the way.

[Pro-SeriesFab]

Bigger is never worse in this case. 7/16 all the way.

Exactly.

The bigger the workholding, usually the better.

Unless you already had the studs and rocker arms, I can't think of a reason why you would take the 3/8 over the 7/16

[Mikej26]

I just switched over to shaft rockers. Not because I needed to, but why not?

I figured they’ll be good To give me room to grow in the future

[GARY C]

I plan 7/16 for everything, if I had a 3/8 application I would make sure it had a stud girdle, it is still possible to break a stud but you have something to hold it together... I have even seen 7/16 with a girdle break a stud so anything is possible.

[travis]

I’m not using a large cam or high rpms, but it appears to me to be pretty aggressive...264/268@.006, .544/.544 lift hydraulic roller.

Thanks guys. Now time to order heads

[Mark O'Neal]

Bigger is never worse in this case. 7/16 all the way.

I don't know anything over about 5'6" and 125 lbs.........

If the rocker stud is larger, then the wall on the polylocks are smaller. So...wouldn't a 3/8 stud with a stud girdle be the best compromise?

Outside of shaft rockers, of course.

[Geoff2]

The rocker studs flex. The flexing causes a loss of lift & duration. If the flexing is bad enough &/or the stud quality poor, the studs can & do break....

So use the thickest studs you can, made of the best steel.

I often fit washers under the studs where practical, between the stud's hex & the stud boss on the head. This places the rocker closer to the stud mount, reducing stud flex. You need to make sure nothing binds & that there is sufficient thread engagement in the head.

[SupStk]

Bigger is never worse in this case. 7/16 all the way.

If the rocker stud is larger, then the wall on the polylocks are smaller. So...wouldn't a 3/8 stud with a stud girdle be the best compromise?

I don't think so. I've seen 3/8" studs with a stud girdle break. Haven't seen but one 7/16 polylock break and it was in a stud girdle.

[sanfordandson]

Bigger is never worse in this case. 7/16 all the way.

If the rocker stud is larger, then the wall on the polylocks are smaller. So...wouldn't a 3/8 stud with a stud girdle be the best compromise?

Absolutely not. The 7/16 polylocks i have are the same wall thickness as the 3/8. OD is increased of course.

[Mark O'Neal]

Bigger is never worse in this case. 7/16 all the way.

If the rocker stud is larger, then the wall on the polylocks are smaller. So...wouldn't a 3/8 stud with a stud girdle be the best compromise?

Absolutely not. The 7/16 polylocks i have are the same wall thickness as the 3/8. OD is increased of course.

If they have a "standard" .550 od yo fit most rocker arms.....how can that be?

[The Badger]

The rocker studs flex. The flexing causes a loss of lift & duration. If the flexing is bad enough &/or the stud quality poor, the studs can & do break....

So use the thickest studs you can, made of the best steel.

I often fit washers under the studs where practical, between the stud's hex & the stud boss on the head. This places the rocker closer to the stud mount, reducing stud flex. You need to make sure nothing binds & that there is sufficient thread engagement in the head.

Not trying to be a smart a**, but have you measured flex before and after? Sure it makes a change just curious as to how much?

[sanfordandson]

If the rocker stud is larger, then the wall on the polylocks are smaller. So...wouldn't a 3/8 stud with a stud girdle be the best compromise?

Absolutely not. The 7/16 polylocks i have are the same wall thickness as the 3/8. OD is increased of course.

If they have a "standard" .550 od yo fit most rocker arms.....how can that be?

They don't have the standard .550 OD...

[Ken_Parkman]

I once chased valvetrain deflections and found (much to my shock) that the stud deflections increased lift. The 7/16" studs reduced lift from 3/8"