After viewing the dyno sheets, Brulé determined the big-block was still suffering from valve float above 6,000 rpm. Our next bout of business was to replace the roller lifters. Initially we had installed a set of hydraulic roller lifters (PN 854-16) because of their ease of use and specific match to the Thumpr roller camshaft. However, Brulé had felt the lifters weren't able to keep up with the camshaft at higher engine speeds. In theory, installing a higher tolerance lifter should help with the upper rpm flogging.