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12803-8 1.940" X 5.422" Exhaust Manley Severe Duty Valves Fits: BB Chevy 5/16"

12803-8 1.940" X 5.422" Exhaust Manley Severe Duty Valves Fits: BB Chevy 5/16"
NOTE: Photo is a general representation and NOT the actual product listed
  
These valves are priced as SETS. The last digit in the part number is the qty included.
GoRacingValves Price: $278.12


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PART NUMBER: MAN12803-8
Qty:

Description
 
Manley Severe Duty Valves

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 degrees is nearly double the competitors' EV-8. At 1000 degrees the Manley NK-844 displays more than four times the ultimate tensile strength of the competitors' best intake material. Further proof of the superiority of the Manley Severe Duty valves is evident in Manley's fatigue tests. In normal operation where valve float is non-existant, a valve will experience 20,000 to 25,000 pounds of applied stress. Hoever, when valves bounce on the seat the stress immediately soars to 40,000 plus lbs. Manley exhaust valves ran to 100 million cycles while competitors' offerings failed at 100 thousand cycles. That's a thousand times BETTER fatigue life! Severe Duty Series valves are made from Superior Stainless for high temperature gasoline engines, feature Chrome Stems, Hard Tips, Swirl Polished Heads, and are fully machined.



APPLICATION(S):
CHEVROLET
V8 Big Block 396-454







MANUFACTURER:  Manley

PART NUMBER:  12803-8

INTAKE/EXHAUST:  Exhaust

HEAD DIAMETER:  1.940"

STEM DIAMETER:  5/16"

OVERALL LENGTH:  5.422"

TIP LENGTH:  .250"

MARGIN: .065"

SEAT WIDTH: .080"

STYLE:  12� X 3/8" angle/radius- 7� Dish Top of Head-Stock Length

TECH NOTES:  Requires Use of Bead Loc Valve Locks

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