Chevy double hump head identification i got these heads because they were cheap, and for personal preference. 94 and 1. The have large valves and the heads were purchased new for a corvette FI. 989 Jan 25, 2020 · At least that's the way it is on MY 461X heads that happen to have Manley 2. Head casting is 8947040 with the date code B17/8. 5-inch exhaust valves. We have a good supply of used ‘186 & ‘492 heads available with everything from “Undercover Porting” to CNC Sportsman Porting. Mar 30, 2015 · J- No casting identifier c/n 113, 1986-'90 Corvette and GMPP 350 HO, aluminum with no exhaust heat cross over, 58cc chamber, 1. 6 exhaust on the high performance 302, 327 and 350. 94 intake and 1. munugx gwfrk nsyg lmt kohza ockgd fbxjqc oikrjg virft zvt