Ok, so i have this damned tapping in my valvetrain and i want to get rid of it. I dont know the base circle of my cam but i know that its probly a smaller one since i do have a fairly good size lift on it. I know that tapping indicates a clearance problem as well. I tried the old, screwdriver stethescope trick and i concluded that it is indeed the valvetrain. Got me some 7.425" pushrods, if i had too much preload on the lifter what would happen? Would i kill the lifters or would i be hanging valves? Basically i want know, will i fubar anything if i go to a 7.425 from a 7.4. I just wanna get rid of this ticking and not have to pull the heads off.

Im too fed up with the truck to check the pr length so

 

i dont know what brand cam you have but with my FMS i have the lift stated below and its got the stock size base circle. but i dont know your lift so that may not matter

 

I'd contact whomever made your cam and ask them if it is a smaller base circle than stock. If it's .050" smaller, you need a .025" longer than stock pushrod. Stock is supposed to be 7.400" long.