Well I finally put new rockers on it, here is the pic of what the cracked one looks like. Look like it might have too much lift? Or maybe it wasnt adjusted right?

Anyway, just thought I would share the pic.
Pic Here

 

Cute . Hope that was the cause, not a symptom. Any piston slap? Valvetrain clacking before it let go? Id make sure things are getting oil as well. Ive had a few stamped rockers break on me. Fired a pushrod through one and stuck in the valve cover once. Thing to watch for if your using stock spec parts is the lack of consistancy. Ive seen them be pretty far off in ratio and thickness.
Good Luck.
CoryM

 

What was your spring seat/open pressure? Stock rockers fail right where yours did from too much spring pressure. Any more pressure than about 110 on the seat will cause the fulcrum area to burn and crack.

Dave

 

seen that happen befor

 

did you put long slots on this time? moderate lift with stock rockers will do that too

 

No.. If this does not do the trick I will go with long slots. I adjusted the valve lash on both sides so hopefully this might fix the problem, if not, long slots it is

 

That looks EXACTLY like you ran out of slot before the cam got to max lift. Front of the rocker slot grabs on the rocker stud, the pushrod keeps pushing up and the bottom breaks outta the rocker. Not usually in one shot- over time. Did you bend a pushrod on this deal? If so I'll lay money on it.

I HIGHLY recommend you check your pushrod length. I'll bet it's too long. Pushrod length and the slot in the bottom of the rocker are tied to eachother. If the pushrod is too long the rocker will already start out nose-forward and then get more and more so as the cam reaches max lift. I have taken standard length slot rockers to well over .500" lift with no problems IF THE PUSHRODS ARE THE RIGHT LENGTH.

If you are up over .500" then you might wish to also upgrade the lubrication to the rocker arm *****. A set of Crane Cool Nuts will allow easy adjustment and also grab oil shot out of the pushrod squirter hole and direct it down to the rocker ball, instead of shooting over the rocker like it normally does. THis aids lubrication and cooling of the rocker.

 

Damon, since we're talking about stock rockers; I'm going to be running a .488"/.510" lift hyd. flat-tappet cam in my 413 small block. With stock length hardened pushrods and the stock stamped-steel guided rocker arms on my Vortec heads (with uncut deck and heads), do you think I'll be okay for valve lift? I'm okay for retainer to guide clearance, but I was curious about the rocker issue and stock vs. long-slots.

Thanks for any info.
Dave

 

No pushrods were bent.

The length may just be too long. I do not know tho. When I talked to the previous owner he told me he cracked one every 1 - 2 months. ( Failed to tell me this until AFTER I bought the car ) Like I said, I re-adjusted the lash on all of them and if this does not work, I will start digging deeper. Im only out $4 on a new rocker arm so...

 

Dirt- no. The Vortecs are all pooped out at about .470" both intake and exhaust. It's not just the springs- the retainers actually hit the valve guides beyond that. Machine work and an appropriate set of springs to go with that cam are called for.

Pacesetter- get a cheap plastic Moroso valve length checker tool and slide it over the rocker stud. You'll know quickly if you're within the realm of sanity or not.

 

Dirt- no. The Vortecs are all pooped out at about .470" both intake and exhaust. It's not just the springs- the retainers actually hit the valve guides beyond that. Machine work and an appropriate set of springs to go with that cam are called for.


Thanks, but I knew all of this already. I have the springs, and the retainer bottoms will be machined. What I wondered about was using the above mentioned cam with stock stamped steel rockers that came on the Vortecs.

Dave