A co worker of mine just installed a cam on a 91 chev 5.7. The truck feels very strong but on the upper rpms it misses. The cam is from comp cams and is a 218/224 with a lobe lift .3080/.3130. He installed lifters, rockers and timing gears. Does he need to install spring too? Any help is appreciated. BTW the time was set a 10 degrees and still misses and at 0 also.