The HiPo engine was engineered to increase performance and high-RPM reliability over standard 289. It had solid lifters with hotter cam timing; 10.5:1 compression; a dual point, centrifugal advance distributor; smaller combustion chamber heads with cast spring cups and screw-in studs; low restriction exhaust manifolds; and a bigger 595 CFM carburetor vs. the standard 289 which had a 480 CFM carburator. The water pump, fuel pump, and alternator/generator pulley were altered; fewer vanes, extra spring, and larger diameter respectively; to help handle the higher RPMs. Even the HiPo’s fan was unique. Bottom end improvements included thicker main bearing caps and balancer, larger diameter rod bolts, and a hardness tested and counterweighted crankshaft, all for high-rpm reliability.

Compare the bottem end components of a 289 and a 289 HiPo, then compare those to yours.