cosworth knocking noise. when on start up from cold the engine sounds mint. until after 2 / 3 minutes then when you up the revs and drop em off again theres a knocking noise. sounds quite heavy. when engines warm it dosent do it, but sounds very cami. its had new block, pistons, crank, shells, tappets, the only thing i didnt change is little end bearings, and cams, it was timmed up the other day by a cozi specialist thinking it was that. but still the same the following day, please help;