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Intake runner volume 246cc-278cc 18 deg. Valve angle 58/107 Valve spacing (same center lines as GM heads) Exhuast Valve 1.625 dia. x 5.550 length* Serdi #'s 1st cut: H1X1-A1 2nd cut: H1X2-B2 Raised Intake runners 5 deg. intake flange (with GM bolt pattern) Spread port exhaust Offset lifters required Pushrods cleared for .550 offest Intake gasket FP 1282 Exhaust gasket FP 52464 HUT 921A Intake runner volume 246cc Combustion chamber volume 56cc Intake Valve 2.150 dia. x 5.550 length* Serdi #'s 1st cut: H1.1N1 2nd cut: H1.1N2 Intake port opening at gasket 2.16H x 1.3W Distance from floor to deck at gasket 1.2 Intake min. cross sectional dim. 2.637 sq. in. HUT 921.1A Intake runner volume 249cc Combustion chamber volume 53cc Intake Valve 2.150 dia. x 5.550 length* Serdi #'s 1st cut: H1.1N1 2nd cut: H1.1N2 Intake port opening at gasket 2.15H x 1.3W Distance from floor to deck at gasket 1.2 Intake min. cross sectional dim. 2.519 sq. in. HUT 921.2A Intake runner volume 254cc Combustion chamber volume 53cc Intake Valve 2.150 dia. x 5.550 length* Serdi #'s 1st cut: H1.1N1 2nd cut: H1.1N2 Intake port opening at gasket 2.16H x 1.32W Distance from floor to deck at gasket 1.2 Intake min. cross sectional dim. 2.642 sq. in. HUT 921.4A Intake runner volume 254cc Combustion chamber volume 56cc Intake Valve 2.180 dia. x 5.550 length* Serdi #'s 1st cut: 2353-B1 2nd cut: H1.1N2-B1 Intake port opening at gasket 2.1H x 1.295W Distance from floor to deck at gasket 1.265 Intake min. cross sectional dim. 2.58 sq. in. * Valve length with 2" installed spring height Generally, smaller bore sizes & lower chamber volumes will cause lower air flow numbers but not necessarily less horsepower. All programs can be reduced in volume approximately 7cc which will reduce air flow above .5 lift approximately 5 CFM. |
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