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GM 10134364 / 24502580 / 12370855 Casting The 364 & 580 are the same cylinder head with exception of .080" material added to the deck and .055" material added to the intake flange on the 580. Additional deck material is to increase combustion chamber volumes. The 855 is a hipped 580. To provide a common reference, all flow numbers are based on a 364 casting. 58/107 Valve spacing 5 deg. Intake flange HUT 921 Intake runner volume 246cc Combustion chamber volume 56cc/65cc Intake Valve 2.150 dia. x 5.550 length* Serdi #'s 1st cut: H1.1N1 2nd cut: H1.1N2 Exhaust Valve 1.625 dia. x 5.550 length* Serdi #'s 1st cut: H1X1 2nd cut: H1X2 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. GM PART # 24502582 HUT 921.1 Intake runner volume 249cc Combustion chamber volume 53cc/64cc Intake Valve 2.150 dia. x 5.550 length* Serdi #'s 1st cut: H1.1N1 2nd cut: H1.1N2 Exhaust Valve 1.625 dia. x 5.550 length* Serdi #'s 1st cut: H1X1 2nd cut: H1X2 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 921.2 Intake runner volume 254cc Combustion chamber volume 53cc/64cc Intake Valve 2.150 dia. x 5.550 length* Serdi #'s 1st cut: H1.1N1 2nd cut: H1.1N2 Exhaust Valve 1.625 dia. x 5.550 length* Serdi #'s 1st cut: H1X1 2nd cut: H1X2 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. *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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