Quote Originally Posted by collins
if thats the case how do ls7 engines run big aftermarket cams with no problem? i think the greater issue is piston/valve clearance. the only rockers i've really heard of breaking are the harland sharps, and even those were teh factory ratio 1.7:1... now valve springs... i've seen a few. mainly that batch comp 918's.


and hey sus, stock valve springs are good to about .575 lift and thats right about where the 1.8:1 rockers put it, so there's really no need for new springs unless you're doing a baby cam along with it.
comp xer lobes are very harsh on valve springs because they open and close the valve much faster than normal lobes. take a xer lobed cam the advertised duration is say 284 intake 286 exhaust the @.50 duration will be 235 intake 237 exhaust. use the same advertised specs on a regular lobed cam the @.50 duration would be 232 intake 234 exhaust. the reasoning is the xer lobes open the valve quicker than regular lobes and this combined with 1.8 rockers is a no-no