Need some help, I have had issues with my valve train. It's been ticking, so I pulled the valve covers and found the pushrods were to short. I used a pushrod length checker and found that the ones in it were 6.243", the checker had me at 6.252. I ordered 6.272, I installed them and they still tick. I installed new 1.6 roller rockers also, it did quiet down some but not completely. I read that u are suppose to add .20-.40 for preload, but I measured them when the lifter was all the way down. After putting the rocker in and new pr I torque them to 20ftlbs. So now nothing is loose now and the pushrods are all still at zero lash even after I ran the hell out of it. So where is the ticking coming from, checked for exhaust leaks and found none. So any advice would help, it has to be simple. One thing is I did not build this engine I bought the car like it is. 306 gt40 heads intake and comp cam 270. 24lb injectors, and bbk cold air intake. Is it possible that it has timing gears? Would they make this racket, is there anyway to find out without tearing down the front?