Originally Posted by 350chevyrob
I do admit i did not have valve springs to match the cam.im thinking of building a new motor.this one was a slap it together and run it engine and i should have known better to do that and expect it to hold up to racing it.next one will be done right and take my time on.i really didn't have that much money in this one just a bunch of parts i had and threw it together
Actually this may well be the answer to the wiped lobe rather than a fault of Comp.
It is always best to go with a kit. The valve train is a place where lots of things can go wrong and often for reasons you don't suspect. When a failure happens it gets to a problem figuring out the old dilemma of which came first the chicken or the egg.
Some examples when mixing a high lift cam and insufficiently strong springs (there's other considerations with the springs but in the interest of keeping things simpler I'll stick to spring pressure) especially where it's a high lift rate the drop back on the closing side can result in the valve bouncing when it hits the seat. This will cause a tick if the lifter does not close the resulting lash and it drives the lifter being hit back into the lobe as the valve comes to seat after the closing ramp has passed the lifter. This condition will be worsened by a lifter that leaks down too quickly either because it's on the leaky end of the acceptable production limits or it's a fast leak down lifter by intent as these tend not to pursue lash in the valve train very quickly.
At the other end is stiff valve springs. These push back on the lifter's plunger with a lot of force. If the lifter is leaking down quickly, again either as a result of being at the fast end of the production tolerance or is designed/selected to be a fast leak down lifter, then in-so-far as the impact with the cam due to unexpected lash is concerned is the same as described above only the cause is different. In this case the valve isn't bouncing but the lifter is not closing the lash that develops fast enough as the lobe moves out from under the lifter on the closing side of a fast executing lobe.
In the old muscle car days the hydraulic cams used a lot of ramp at both the opening and closing ends which is one reason why these old style cams have a lot of duration and not a great deal of lift as it was a technique for keeping the valve train quiet by not letting the lifter get into the problems I describe.
There really isn't a cure for this and that includes adjusting the lifter plunger deeper into the body, it is rather the nature of the beast. If you're going to run cams like Comp's XE or Lunati's Voodoo then you're going have this problem to some extent. It will sound worse with a fast leak down (anti-pump up) lifter.
The solutions such as they are runs in two schools of thought:
1) Fully collapse a fast leak down lifter which of course requires a longer push rod to put the rocker and valve stem travel back into alignment. This wipes out any variable timing based on lifter leakdown rates from things such as the Rhoads lifter.
2) Using lifters with slow leakdown rates and running them with the plunger/pushrod cup nearly against the top end retainer so they can't pump up to a point that unseats the valve. This requires using a Circlip to retain the plunger if the lifter has a the wire retainer to insure enough retainer strength to keep the plunger/push-rod cup from popping out the top.
In the end you should always use the valve train components, especially valve springs, retainers, and lifters recommended or kitted by the camshaft manufacturer as you can be pretty assured that they have tested this combination across the operating range and know it's successful as a combination of parts.