Chevrolet Repair: 350 chevrolet, dirt track car, mile dirt

Question
I have a early 70's block decked.050 It's bored .040 over. It also has a rotating assemble of a eagle crank and eagle 5.7 rods with floating pin. camshaft is a elgin e-920-p specks on cam are as follows lift 320 intake and exh. valve lift intake and exh. 480. I also have a set of keithblack 120  pistons for heads I using vortech #12558060 valves 194-160 I also running aluminum elderbrock intake #1776 I have a top in rattle it sounds to me like a solid lift cam any thoughts on why I am having a rattle. Please let me know. Everything in the engine is brand new. Its a 3/8 mile dirt track car. Several people are running  this setup with no problems. why am I having problems.

Answer
I can't really answer this very well because I have never worked with something like this but just about the only thing that could cause any noise in the top end is the valves or lifters. It may just need some more tweaking. But a rattle would suggest a piston or rod problem but more than likely a piston. I once had an old 383 that had a rattle. I took the heads off and discovered that the top of a piston had stripped about half of the outer lip. Never seen it before and it still ran.