Issue with Stamped Steel Rockers in BB Chevy

Chris Hill · 06-02-2008, 11:48 PM

In my previous professional life, generally when you had a valvetrain failure, the failure was caused by an impact somewhere in the valvetrain. The impact occurred when unwanted lash occurred in the valvetrain.

The major causes of lash comes from too little valvespring force either from too small valve spring load or a valve spring harmonic issue that causes too small valve spring load (beehive springs help with this). Also, the valvetrain can have another issue with the entire system (not including valve spring stiffness) stiffness and mass and it can be excited into a harmonic issue. To say controlling a valvetrain effectively is difficult is a gross underestimate, especially at the high rpm necessary to make good power.

You say the major wear items are fulcrum area wear, rocker arm stud breakage, piercing of the rocker arm push rod cup. I would believe that when you have lash and impact, the force on each of these areas would increase exponentially and overstress and fail the rockerarm or stud if this happens repeatedly.

The rocker arm failing may be the reliability issue racers have experienced. But more than likely, the proper solution is to have a properly designed valvetrain system that will eliminate unwanted valvetrain lash during engine operation. We have used Chris Padgent at Lunati then Comp Cams for our camshafts for almost 20 years and have good reliability and we’ve always been pretty competitive in the classes we’ve run.

On the last v-6 I put together, I think I had 125 or 135 lbs of force on the seat, nothing very high. This was with a standard lifter face. Dad’s v-6 he built that was stupid fast has Schubeck lifters and around 180 to 200 lbs on the seat. Unfortunately, I can’t remember any of the peak lift force numbers.

SSDiv6, thanks for the points you have presented in the other thread. I have enjoyed reading them.

Thanks,

06-02-2008, 11:48 PM	#4
Chris Hill Senior Member Join Date: Jan 2002 Posts: 655 Likes: 8 Liked 244 Times in 26 Posts	Re: Issue with Stamped Steel Rockers in BB Chevy In my previous professional life, generally when you had a valvetrain failure, the failure was caused by an impact somewhere in the valvetrain. The impact occurred when unwanted lash occurred in the valvetrain. The major causes of lash comes from too little valvespring force either from too small valve spring load or a valve spring harmonic issue that causes too small valve spring load (beehive springs help with this). Also, the valvetrain can have another issue with the entire system (not including valve spring stiffness) stiffness and mass and it can be excited into a harmonic issue. To say controlling a valvetrain effectively is difficult is a gross underestimate, especially at the high rpm necessary to make good power. You say the major wear items are fulcrum area wear, rocker arm stud breakage, piercing of the rocker arm push rod cup. I would believe that when you have lash and impact, the force on each of these areas would increase exponentially and overstress and fail the rockerarm or stud if this happens repeatedly. The rocker arm failing may be the reliability issue racers have experienced. But more than likely, the proper solution is to have a properly designed valvetrain system that will eliminate unwanted valvetrain lash during engine operation. We have used Chris Padgent at Lunati then Comp Cams for our camshafts for almost 20 years and have good reliability and we’ve always been pretty competitive in the classes we’ve run. On the last v-6 I put together, I think I had 125 or 135 lbs of force on the seat, nothing very high. This was with a standard lifter face. Dad’s v-6 he built that was stupid fast has Schubeck lifters and around 180 to 200 lbs on the seat. Unfortunately, I can’t remember any of the peak lift force numbers. SSDiv6, thanks for the points you have presented in the other thread. I have enjoyed reading them. Thanks, __________________ Chris Hill https://ihmusedparts.com