Enginetech BC296J / BB253J Main and Rod Bearing Set for 1968-2002 Chevrolet Small Block 5.7L 350 327 307 305 V8 LT1Bearing Material: Bi metal, silicon aluminum Enginetech Rod & Main Bearings Enginetech main & rod bearings the choice of rebuilders for over 25 years. About ten years ago, when aluminum bearings were first being introduced, Enginetech continued to produce the higher quality tri metal 780 bearings. Enginetech stuck firm with the 780 tri metal material for years because it was far superior to the early aluminum bearing technology. Advanced technology in