Why do i need adjustable pushrods?

Guys, this might sem a stupid question, but bear with me.
when I built my 360 two years back, my standard pushrods were too short. I have used adjustable pushrods ever since and have to set the preload manually. My simple question is why did this situation occur?

Engine spec
360 block-standard height, not decked
Comp Cams XE262 grind. 47 lift.
Smog heads completely rebuilt inc new seats and back cut. Lightly cut/skimmed to true the gasket face
Not a radical set up.
ANy ideas? I would really like to just use fit n, forget pushrods.

This is interesting: First I replied to your question about the possible lifter/cam damage (another posting...) like I had and now you mention the same situation I had with my pushrods! I'm running a 360 block with a Comp Cam .488/.491 and Edelbrock heads and Crame roller rockers. Sounds EXACTLY like MY engine!



I had Smith Brothers http://www.pushrods.net/ make me a set of 7.00" push rods so I could get a correct adjustment on my rockers.