stud upgrade for factory rockers

[MidnightriderZ24]

i would like to run some studs to replace the factory bolts, has anyone tried this to help prevent the rockers from pulling out of the head for high rpm??

[Google Adsense]

[betterthanyou]

Drill and tap it for M10 bolts like the old heads had. If the bolt is just straight ripping the metal out of the heads then studs vs bolts wont make a difference.

[Mars]

this may also be caused by over-torquin'....

[Superdave]

I just use Loctite red and a prayer to the 60v6 gods.

[bob442]

I've had my rockers on and off 5 times now, no problems-yet, how ever I am following the torque specs to a T with the torque wheel, And you can positively feel where the fastener is at its limits right when you get to 28-30*

[MidnightriderZ24]

guys that isnt the point. ive seen a few 10mm and 8mm rockers pull out of heads under daily conditions. i just want to ensure i wont at 8000 maybe higher rpms. torquing the rockers inst an issue, i trust my snap on tech-wrench. wanted an opinion on a stud versus a traditional bolt. im pretty sure i have it solved by drilling to a 10mm, with a stud.

[bob442]

is the fastener stripping or the head?

[NateD4]

Are you having issues with the bolts loosening up or are you just afraid they will at high RPM?

If the former you may have some thread issues in the heads (I'm assuming they are aluminum??). If that is the case there are a few fixes.

In the case of the later (which I am dealing with on my build as well) the issue is concern for seating forces.

On Genn III and later heads (to my knowledge) the rockers contain a square looking, boss that is part of the rocker/bolt assembly. This is intended to help reduce stress on the bolt. It primarily helps with the back and forth bending force applied to the bolt and aids in eliminating some of the tendancy for the bolt holes to elongate under extreme wear.

To my knowledge I have never personally seen or heard of a stock engine with an issue where the bolt hole was elongated or pulled out (anyone else have any input on that?).

The 'easiest' way to assure the rockers you have will run to higher RPM without bolt failure is to carefully examine the following options:

1) Drill the thread longer (may be tough, or weaken the head depending on where and how you drill).
2) Use the GM square pedistals or similar when possible (making their base larger may help depending on whether there is room or a spot face on the head that accomodates larger than stock).
3) Consider using a threaded insert. This option increases the shear stress area and thus available force on the bolt. However you could weaken the surrounding metal.


The last more expensive option (assuming you area already running aftermarket rockers) is to make a girdle for them... not sure how easy or good this will be... but I'm looking into it for my build....

Anyone else have any additional comments?

[veekuusi]

- stock 3400 = bottom M10 , top M10

- aftermarket roller rockers = bottom M10 , top 3/8

- my project = bottom 7/16 , top 3/8 (ARP)

I am updating my rocker arm studs to longer ones .
Because probably need longer valve springs and therefore longer valves.
Have to drill the hole in the head larger and put a helicoil insert.
I can not do the job in my garage , my friend is doing that job.
That is why no pictures yet.
Most difficult is to drill the new larger hole downright.

There is not much material round the hole.
The helicoil insert makes it stronger , but it can still break down , because the aluminum
fall to pieces.

I understund there is not problem with the studs in normal usage.
But when you have high revving engine with heavy valve spring loads, that is
when this maybe an issue.

I am working on a stud girdle also.
That is not brought to the desired final state yet.

[mfuller]

Well, if/when my 8mm rocker arms fail when spinning the motor to 7000rpm with PAC 1518 springs and a WOT Race cam, I'll let you know.

A few numbers:

At a 1.76" install height, the PAC 1518 spring has a spring pressure of 142.53#.
At maximum intake valve lift of .570", the spring pressure is 321.13#.
At maximum exhaust valve lift of .555", the spring pressure is 318#.

That makes the PAC 1518 a bit stiffer than Superdave's Comp 26915 springs.
So basically I'm in the same boat praying to the 660 gods.