I have a set of untouched close chambered 1967-1969 Buick 430 "Tall Port" heads casting #1382983. Does anyone know what size the combustion chamber is? What would the compression be on a 1970 455 with flat top pistons? Thanks... Justin 72buickgs@myway.com
Justin, Untouched, that 983 head is typically around 68 CC with small valves, 65-66 cc with Stg valves. Your compression question is a little vauge, as factors such a type of gasket, deck height, piston notch CC and bore size all figure into the equation. But, with a .040 gasket, the pistons at zero, and 9 cc valve reliefs, you would be at 11.75 with the 68 cc chambers. JW
