Dart Machinery, LTD. stands behind each product we manufacture 100%. Each component undergoes a detailed manufacturing process that involves the hundreds of calculated and precision steps to ensure the finest quality possible.

Warning This product contains chemicals known to the State of California to cause cancer and reproductive harm. www.P65Warnings.ca.gov
PRO1 23 227cc CNC

PRO1 23° 227cc CNC



Maximum performance/full competition, unlimited oval and super classes. 7,000+ RPM, 400+ cubic inch engines.

Dart PRO1 23° 227cc CNC heads are professional quality competition cylinder heads. We applied the airflow technology developed in our championship winning Pro Stock engine program to produce these state of the art heads.

Every intake port, every exhaust runner, every valve bowl and every combustion chamber is 100% CNC machined on special dedicated PRO1 castings. These heads are ideal for high compression, big cubic inch small blocks and are great for supercharged applications.

Standard valve angle and spacing are retained to allow use of off the shelf pistons and valve train components.

Hardened exhaust seats are compatible with unleaded gasoline. Manganese Bronze valve guides extend cylinder head life.

Heads are sold individually.


Material: RMR Cast Aluminum Alloy

Valve Angle: 23° (stock)

Intake Port Volume: 227cc CNC

Intake Valve: 2.080”

Exhaust Valve: 1.600”

Chamber Volume: 66cc

Plug Type: Angle

PRO1 23° 227cc CNC – Aluminum (Angle Plug Heads)

66cc Combustion Chambers

11970040P – Bare Head

11971142P – 1.437” Dual Springs for Hydraulic Roller or Solid Flat Tappet Cam .620”

11971143P – 1.550” Dual Springs for Solid Roller Cam .660”

PRO1 227 Tech Sheet – H17