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Dart PRO 1 CNC heads are professional quality competition cylinder heads. Every intake port, exhaust runner, valve bowl, and combustion chamber is 100% CNC machined on special dedicated PRO 1 castings. CNC machined 227cc intake ports give you optimized flow characteristics out of the box. Our 5-axis machining centers precisely duplicate the port profiles so that every head delivers awesome performance. CNC machined combustion chambers ensure that every chamber has the same volume so that every cylinder has equal compression.The valve seats are machined, not ground, to produce precise angles and radiuses for maximum airflow.

Cylinder Head Style: Assembled

Cylinder Head Material: Aluminum

Cylinder Head Finish: Natural

Combustion Chamber Volume (cc): 64

CNC-Machined Combustion Chamber: Yes

Intake Runner Volume (cc): 227cc

Exhaust Runner Volume (cc): 85cc

CNC-Machined Intake Runner: Yes

CNC-Machined Exhaust Runner: Yes

Combustion Chamber Style: Heart

Intake Port Location: Standard

Exhaust Port Shape: Square

Exhaust Port Location: Standard

Spark Plug Style: Angle

Intake Valves Included: Yes

Intake Valve Diameter (in): 2.080 in.

Exhaust Valves Included: Yes

Exhaust Valve Diameter (in): 1.600 in.

Valve Springs Included: Yes

Maximum Valve Lift (in): 0.690 in.

Outside Diameter of Outer Spring (in): 1.550 in.

Damper Spring Included: Yes

Number of Springs Per Valve: Dual

Retainers Included: Yes

Retainer Material: Titanium

Locks Included: Yes

Lock Style: 10 degree

Valve Stem Seals Included: Yes

Valve Stem Seal Style: Positive stop

Rocker Arm Studs Included: Yes

Rocker Arm Nut Thread Size: 7/16-20 in.

Rocker Arms Included: No

Rocker Arm Nuts Included: No

Guideplates Included: Yes

Guideplate Pushrod Size: 5/16 in.

Valve Cover Mounting Style: Center and perimeter bolt

Accessory Bolt Holes Drilled: Yes

Intake Valve Angle: 24

Exhaust Valve Angle: 15

Valve Guides Included: Yes

Valve Guide Material: Manganese bronze

Valve Seats Machined: Yes

Valve Seat Machine Style: 4-angle intake/3-angle exhaust

Valve Seat Material: Ductile iron

Steam Holes Drilled: No

Oiling Style: Through pushrod

Machined for O-Ring: No

Heat Crossover: No

Quantity: Sold individually.