I tried LT1 tech with no help over two days time. Here is the original post from there:

I am trying to decide on if I need shaft mount rockers for my setup. Here is what I will be running:

fully forged Callies 383 setup
Stage 3 Jordon Musser ported LT4 heads/intake
58mm TB
Longtubes through true duals
solid roller Cam Motions Camshaft (nothing crazy but around .650 lift 240s/250s duration)
300-350 direct port NX setup

I have been told that 1.6 Pro Mags are fine and then I have also been told that I HAVE to run shaft mounts. So, if you state that I need the shaft mounts, please explain to me why I do.

THanks

 

Hi TexasTA,

You'll probably get a few well reasoned replies but my seat of the pants response might clarify your thinking. I have been working up a fairly similar setup and in my mind I drew a line at 7,000 rpm for the cutoff to switch to shaft mounted rocker arms. If you keep that duration down around 240's you won't need to spin that high. If you get to 250+ you'll wish you could spin to 7200-7400.

Rick

 

Usually you run shaft mount rockers because:

1. You are running lots of lift and don't want the flex associated with stud mount rockers
2. You wanna run some serious, and or continuous RPMS
3. You are running RR heads which require offset lifters and shaft mount offset rockers

 

.

 

I know Jordon . I can't stop getting people who hear of the setup I am going with saying, "I sure hope you are running Shaft mounts."

I know you, Shawn, and my damn wallet are telling me to run the 1.6 Pro-Mags.

I guess I am just going to "take my chances" with the Pro-mags.

Oh and I am going to be stopping by the shop to pick up that cam and pushrods around the end of February or very first of March on my way to houston. I will call you when the time comes.

 

You can run a stud girdle. There are millions of people out there with them. I have crane gold rockers on 3/8ths studs and a double bar girdle on my 355. No problems here.
Are shaft rockers better, yep with high spring pressures, high lift, lots of rpm. If you use a girdle just make sure you go over the valve adjustment a few times before you start it as it will pull all of the studs in line, so first time adjustment is a pain. After that your good.