designed to withstand 600°f specially formulated silicone developed to be compatible ... in a performance street racing engine application part no 5820 5821 5822 5812 ... 1.31w x 2.31h lg race port 86-91 350 v8 w/tpi all 396-454 1/16 thick cork ... use w/manifolds w/o upper bolt holes ford 65-67 289-302 exc factory hp 1/16 ... 1/16 thick 1.25w x 2.11h 86-95 302 v8 efi 70-74 351c-v8 4 bbl chrysler/dodge/ ... extra large square port 2.09 x 2.09 ford/mercury all 302 oval port 62-90 221- ... 400 oval port 1.58w x 1.96h 70-74 351c-v8 68-88 429-460 oval port 1.25w x 2.08h ... 07-up 5.4l dohc round port chrysler/dodge/plymouth 67-74 273-318 stock port 1.34w ... rubber material combination compensates for surface irregularities and resists high ... temperature incorporates steel carrier for stability and proper gasket alignment ...