Highest lift with pressed-in studs??

[calpolymustang]

This is on the same topic as the thread about me wiping out a cam lobe.

Whats the max lift I should use in an engine with pressed-in studs?

My valve spring specs:

Max Net Lift w/.060'' Clearance: 0.560''
Seat Pressure: 98 lbs. @ 1.700'' seat, 260 lbs @ 1.200'' open
Coil Bind: @ 1.080''
Rate (lbs/in): 328 lbs/in

These springs were used with my old 484/484" lift cam (218/218 dur. @ 50, 110) and original style rocker arms.

Im trying to decide between the CompCams XE256 (477/484) and XE262 (493/500).
The 262 looks nice, but I'm worried about 500 lift with my studs.

Any thoughts?

 

[htwheelz67]

I think anything over the xe 256 is pushing it, the extreme cams really need matching springs to work as designed. I'm not a cam expert but have lots of experience with cams. With stock studs stay smaller, I still love the old "high energy" comp grinds, the 260h and 268H are very close in power to the xtreme grinds, depending on combo will match or beat them. They are very easy on the valvetrain compared to the xtreme grinds, I wouldn't be surprised at all if the high energy 268h made more power than your old cam did, duration @0.50 and lift means little, the ramps, duration and lift throughout the "curve" is what matters in relationship to your combo, I've many times went faster with a smaller cam matching my engine than with a bigger one that didn't. if you want some "lope" go the 268h if just a little "burble" go the 260h, they are both about the same to 4500 rpm but the 268 will give about 15 more hp above that, they are both ground advanced so low end isnt mushy. I didn't know about the pressed in studs on my other post...........the nostalgia cam would work in the lift department.

 

[ratio411]

I run .488" lift.
I am worried a stud might pull.
I know folks that ran .500" and never pulled a stud, but I know folks that pulled studs in the .470"s.

I think spring pressure, RPMs, and how fast it can rev all play into the stud pullin'.

 

[htwheelz67]

absolutely right.........but better safe than sorry

 

[D.Hearne]

Comp recommends screw in studs with all the XE grinds. It's the springs, ramp rates in addition to total lift that come into play.

 

[rbohm]

as noteed it isnt the amount of lift a cam has, it is the spring rates, ramp rates, and rpms that cause the problems. invest the time and money in screw in studs.