GM 990

No longer available, the 188 head has replaced this one, but that's not to say they can not be found..

• PORT SIZE: 318
• CHAMBER: 118cc
• VALVE SIZE: 2.19 / 1.88
• PRICE: N/A
• FLOW@.100: 69 / 53
• FLOW@.200: 125 / 103
• FLOW@.300: 183 / 140
• FLOW@.400: 233 / 176
• FLOW@.500: 264 / 198
• FLOW@.600: 292 / 204