do you have aftermarket camshafts, like stage 2 or 3??? if you do, do you have the valve train to handle the high lifts on the camshafts??? Cause with stage 2 or 3 camshafts running on stock valvetrain will cause valve float and the valves will be hitting the pistons thus reducing the life of you engine and that may be were the sound is coming from.
Or... Are you idling high even when the car has warmed up?????If your hearing
valve tick your Ignition Timing timing might be off or even having it set to manufacturer specifications on a modify motor can cause problems, you will need to change the igition timing to meet the specs of your mods. Get a timing gun and check the timing by first losenng the dizzy and then attaching the gun to the #1 spark plug wire and the battery then point the gun at the crank pully and pull and hold the triggler, you will notice a pointer in the shape of a triangle on the block, colored marks on the crank pulley. Each mark designates a certain spark advance. The upper single white mark is 0BTC. You will also notice a cluster of three marks that are very close together. The center mark is 16 degrees BTC while the mark closest to the front of the car is 18 deg BTC and the other is 14 degrees BTC. Well now just tap on the dizzy ( you will notice the timing marks on the crank pully are moving, try to keep one of the marks lined up to the pointer on the block) now just time it to you fell the car is running good and idling at about 900-1000 rpm's. If this was the problem the ticking noise should be gone or not as loud as it was, its okay for a built motor to make noise, as long as its not something out of the ordinary. YOU SHOULD ALSO GET THE CAR TUNED EVEN IF ITS DRIVING GOOD AND IDLING GOOD TO YOU, THERE STILL MAY BE SOME TWEEKS THAT COULD DAMAGE YOUR ENGINE OR PARTS AND THUS REDUCING THE LIFE OF EVEN A FULLY BUILT ENGINE.