i have a little lifter noise and i want to change cams. its a stock 327, on a 10k rebuild, 600 ed carb,headders,2 1/2 pipes. i think i need to know how big can i go w/out changing the springs. rob

Why not call a cam company and ask them?

UD HAROLD hangs out in the performance forum off and on. He is a cam guru and there are other folks with great knowledge too. You might try a question there. Try to add a bit more info of the engine combo(compression, pistons, etc). That will help on getting a good answer. good luck.