hello. I have my vortec heads at the machine shop. What is the safe lift with press in studs? I realy don't want to spend an extra $200.00 if it will work with my .480 lift cam. Thanks. Bryan

 

There is no "safe lift" with press in studs. Stamped steel rockers only have so much travel before they hit the stud but using roller rockers or long slot rockers solve that problem. Factory rockers are usually safe to around .500 lift.

The problem with press in studs is spring pressure. Typical factory spring pressure is 80-100 pounds seat pressure. If spring pressure is too high, it can pull the studs out of the head as the rocker is trying to open the valve. Having open pressure in the 250+ range really needs screw in studs.

 

Good answer Stephen

In addition to that, even a low spring pressure can cause issues with press
in studs at high RPM.

The faster the opening velocity, the more stress placed on the stud.

Therefore even a stock spring type pressure can be too much for a quick
opening valve at 5000+ RPM.

Spend the money and do it right if you plan to buzz this motor to the moon
frequently.

 

You can drill and roll pin the rocker studs yourself for a few $$$s

 

I think if the heads are already at the machine shop it would be silly not to have it done. Even if they are fine with your current cam you will be limited in the future.