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ATK High Performance 250cc LS1/LS6 Aluminum Cylinder Heads HPLS1250
Part Number: HPE-HPLS1250
ATK High Performance 250cc LS1/LS6 Aluminum Cylinder Heads
Cylinder Head, 250cc LS1/LS6, Aluminum, 61cc Chamber, 250cc Runner, 2.080 in. Intake Valve, 1.600 in. Exhaust Valve, 0.650 in. Max Lift, Chevy, Each
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Estimated Ship Date: Nov 13, 2026 Would you rather pick it up?
Overview
Brand:
Manufacturer's Part Number:
HPLS1250
Part Type:
Product Line:
Summit Racing Part Number:
HPE-HPLS1250
UPC:
00653517731853
Combustion Chamber Volume (cc):
61
Intake Runner Volume (cc):
250cc
Exhaust Runner Volume (cc):
105cc
Cylinder Head Style:
Assembled
Cylinder Head Material:
Cast aluminum
Camshaft Style:
Hydraulic roller
Intake Port Shape:
Cathedral
Intake Valve Diameter (in.):
2.080 in.
CNC-Machined Combustion Chamber:
No
CNC-Machined Intake Runner:
No
CNC-Machined Exhaust Runner:
No
Combustion Chamber Style:
Heart
Intake Port Location:
Standard
Exhaust Port Shape:
Round
Exhaust Port Location:
Raised
Spark Plug Style:
Angle
Intake Valves Included:
Yes
Exhaust Valves Included:
Yes
Exhaust Valve Diameter (in.):
1.600 in.
Valve Springs Included:
Yes
Maximum Valve Lift (in.):
0.650 in.
Outside Diameter of Outer Spring (in.):
1.304 in.
Damper Spring Included:
No
Number of Springs Per Valve:
Dual
Retainers Included:
Yes
Retainer Material:
Titanium
Locks Included:
Yes
Lock Style:
7 degree
Valve Stem Seals Included:
Yes
Valve Stem Seal Style:
Positive stop
Rocker Arm Studs Included:
No
Rocker Arm Nut Thread Size:
M8 x 1.25
Rocker Arms Included:
No
Rocker Arm Nuts Included:
No
Guideplates Included:
No
Guideplate Pushrod Size:
3/8 in.
Valve Cover Mounting Style:
Centerbolt
Accessory Bolt Holes Drilled:
Yes
Intake Valve Angle:
11
Exhaust Valve Angle:
11
Valve Guides Included:
Yes
Valve Guide Material:
Manganese bronze
Valve Seats Machined:
Yes
Valve Seat Material:
Powdered metal
Cylinder Head Color:
Natural
Finish:
Natural
Steam Holes Drilled:
Yes
Oiling Style:
Through pushrod
Machined for O-Ring:
No
Heat Crossover:
No
Remanufactured:
No
Quantity:
Sold individually.
Notes:
Six bolt cylinder head. Includes rocker stands. Will not fit bore size under 3.900 in. Viton valve stem seals. Exhaust port raised 0.086 in. 14mm x 0.708 in. reach tapered seat spark plug recommended.
ATK High Performance 250cc LS1/LS6 Aluminum Cylinder Heads
ATK High Performance 250cc LS1/LS6 aluminum assembled engine cylinder heads are complete new builds. They include valves, valve springs, valve spring retainers, valve stem seals, and soft plugs. All threads are checked and repaired, if necessary; and all passages and part interfaces are pressure checked.
Product specifications:
* Material: A356 aluminum
* Bolt count: 6-bolt head
* Intake port volume: 250cc
* Intake port dimension: 3.227 in. H x 1.119 in. W
* Intake port location: Stock cathedral port
* Intake valve size: 2.080 in.
* Intake valve material: Stainless steel
* Exhaust port volume: 105cc
* Exhaust port dimension: 1.628 in. H x 1.722 in. W
* Exhaust port location: .086 in. raised
* Exhaust valve size: 1.60 in.
* Exhaust valve material: Stainless steel
* Combustion chamber size: 61cc
* Valve cover bolt pattern: Perimeter bolt
* Valve angle: 11 degree
* Valve spring pocket diameter: 1.610 in. O.D.
* Valve spring pac: 1905 dual spring (hydraulic roller)
* Valve spring setup height: 1.800 in.
* Valve spring closed pressure: 160 lbs. (with retainer)
* Valve spring open pressure: 1.200 in., .600 in. lift, 425 lbs. / 1.150 in., .650 in., lift 445 lbs. (with retainer)
* Valve spring max lift: .650 in.
* Valve guide material: Manganese bronze
* Valve seal material: Viton©
* Valve seat material: Powder metal
* Retainer material: Titanium
* Deck thickness: .750 in.
* Minimum bore diameter: 3.900 in. (will not fit stock bore 4.8L/5.3L)
* Flat mill: .006 in. per cc
* Spark plug dimensions: 14mm x .708 in. with tapered seat
* Torque specifications per application based on factory or aftermarket bolts/studs
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