World Products 042670 - Cylinder Head Cast Iron Chevy Small Block S/R Torquer 170cc 76cc 23Degree 2.020" x 1.600" Straight Plug, Bare CastingWorld Products 042670 Cylinder Head Cast Iron Chevy Small Block S R Torquer 170cc 76cc 23Degree 2. 020" x 1. 600" Straight Plug, Bare Casting World's SR TORQUER provides up to 30HP over stock Head. The S R Tourquer cylinder head is the preferred performance alternative to expensive OEM castings or junkyard rebuilds. These Head are designed with extra thick decks and walls for improved reliability as well as equipped with hardened steel exhaust seats