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The Severe Duty® series of valves is the Manley signature in the performance and racing industry. Exhaust material XH-428 and intake material NK-844 is offered by no competitor in the world. And no pair of materials show such clear dominance over all others. Ultimate tensile strength of XH-428 at 1500°F is nearly double the competitors’ EV-8. At 1000°F the Manley NK-844 displays more than four times the ultimate tensile of the competition’s best intake material.
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Manley 11661-8 Severe Duty Valves Manley 11661-8 - 1.590" Exhaust - Severe Duty Stainless Steel Valves

Manley 11661-8  LS3, L92 and L99 Severe Duty Stainless Steel Exhaust Valves

Our Price: $218.99
Manley 11673-8 Severe Duty Valves Manley 11673-8 - 1.550" Exhaust - Severe Duty Stainless Steel Valves

Manley 11673-8  LS1, LS2 and LS6 Severe Duty Stainless Steel Exhaust Valves

Our Price: $218.99
Manley 11675-8 Severe Duty Valves Manley 11675-8 - 1.575" Exhaust - Severe Duty Stainless Steel Valves

Manley 11675-8  LS1, LS2 and LS6 Severe Duty Stainless Steel Exhaust Valves

Our Price: $218.99
Manley 11677-8 Severe Duty Valves Manley 11677-8 - 1.600" Exhaust - Severe Duty Stainless Steel Valves

Manley 11677-8  LS1, LS2 and LS6 Severe Duty Stainless Steel Exhaust Valves

Our Price: $218.99
Manley 11679-8 Severe Duty Valves Manley 11679-8 - 1.615" Exhaust - Severe Duty Stainless Steel Valves

Manley 11679-8  LS7 Severe Duty Stainless Steel Valves Exhaust Valves

Our Price: $218.99
Manley 11680-8 Severe Duty Valves Manley 11680-8 - 2.055" Intake - Severe Duty Stainless Steel Valves

Manley 11680-8  LS1, LS2 and LS6 Severe Duty Stainless Steel Intake Pro Flo Valves

Our Price: $218.99
Manley 11682-8 Severe Duty Valves Manley 11682-8 - 2.080" Intake - Severe Duty Stainless Steel Valves

Manley 11682-8  LS1, LS2 and LS6 Severe Duty Stainless Steel Intake Pro Flo Valves

Our Price: $218.99
Manley 11684-8 Severe Duty Valves Manley 11684-8 - 2.100" Intake - Severe Duty Stainless Steel Valves

Manley 11684-8  LS1, LS2 and LS6 Severe Duty Stainless Steel Intake Pro Flo Valves

Our Price: $218.99
Manley 12347-8 Severe Duty Valves Manley 12347-8 - 1.590" Exhaust - Severe Duty Stainless Steel Valves

Manley 12347-8  LT1 Severe Duty Stainless Steel Valves Exhaust Valves

Our Price: $227.99
Manley 11688-8 Severe Duty Valves Manley 11688-8 - 2.205" Intake - Severe Duty Stainless Steel Valves

Manley 11688-8  LS7 Severe Duty Stainless Steel Valves Intake Pro Flo Valves

Our Price: $237.99
Manley 12352-8 Severe Duty Valves Manley 12352-8 -2.120" Intake - Severe Duty Stainless Steel Valves

Manley 12352-8  LT1 Severe Duty Stainless Steel Valves Intake Pro Flo Valves

Our Price: $244.99
Manley 11686-8 Severe Duty Valves Manley 11686-8 - 2.165" Intake - Severe Duty Stainless Steel Valves

Manley 11686-8  LS3, L92 and L99 Severe Duty Stainless Steel Intake Pro Flo Valves

Our Price: $254.99
Manley 12354-8 Severe Duty Valves Manley 12354-8 - 2.165" Intake - Severe Duty Stainless Steel Valves

Manley 12354-8  LS3, L92 and L99 Severe Duty Stainless Steel Intake Pro Flo Valves

Our Price: $254.99
Manley 12355-8 Severe Duty Valves Manley 12355-8 - 1.600" Exhaust - Severe Duty Stainless Steel Valves

Manley 12355-8  LS3, L92 and L99 Severe Duty Stainless Steel Exhaust Valves

Our Price: $259.99
Manley 11680H-8 Severe Duty Hollow Stem Valves Manley 11680H-8 - 2.055" Intake - Severe Duty Hollow Stem Stainless Steel Valves

Manley 11680H-8  LS1, LS2 and LS6 Severe Duty Hollow Stem Stainless Steel Intake Pro Flo Valves

Our Price: $479.99
Manley 11682H-8 Severe Duty Hollow Stem Valves Manley 11682H-8 - 2.080" Intake - Severe Duty Hollow Stem Stainless Steel Valves

Manley 11682H-8  LS1, LS2 and LS6 Severe Duty Hollow Stem Stainless Steel Intake Pro Flo Valves

Our Price: $479.99
Manley 11684H-8 Severe Duty Hollow Stem Valves Manley 11684H-8 - 2.100" Intake - Severe Duty Hollow Stem Stainless Steel Valves

Manley 11684H-8  LS1, LS2 and LS6 Severe Duty Hollow Stem Stainless Steel Intake Pro Flo Valves

Our Price: $479.99
Manley 11686H-8 Severe Duty Hollow Stem Valves Manley 11686H-8 - 2.165" Intake - Severe Duty Hollow Stem Stainless Steel Valves

Manley 11686H-8  LS3, L92 and L99 Severe Duty Hollow Stem Stainless Steel Intake Pro Flo Valves

Our Price: $479.99
Manley 11688H-8 Severe Duty Hollow Stem Valves Manley 11688H-8 - 2.205" Intake - Severe Duty Hollow Stem Stainless Steel Valves

Manley 11688H-8  LS7 Severe Duty Hollow Stem Stainless Steel  Intake Pro Flo Valves

Our Price: $579.99
Manley 12354H-8 Severe Duty Hollow Stem Valves Manley 12354H-8 - 2.165" Intake - Severe Duty Hollow Stem Stainless Steel Valves

Manley 12354H-8  LS3, L92 and L99 Severe Duty Hollow Stem Stainless Steel Intake Pro Flo Valves

Our Price: $579.99