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 20 451cc Cnc Portside

PRO1 20° 451cc CNC

Categories: , ,


Maximum competition, high torque, high compression – low dome. 8000+ RPM, 500+ cubic inches.

Dart developed the first successful aftermarket Aluminum heads for big blocks, and we’ve continued to improve and refine our revolutionary designs through our research and development. We now offer the latest of our advancements in the PRO1 20° 440cc Aluminum cylinder heads. These help to bridge the gap between conventional heads and Dart’s Big Chief heads.

Dart big block heads deliver superior performance, by utilizing 440cc runners in a conventional asymmetrical port design, and featuring a 20° rolled valve angle with redesigned shallow combustion chambers. These heads are ideal for maximum effort naturally aspirated, big boost forced induction, or nitrous applications.

Designed to use conventional BBC
intake manifolds.

Requires use of shaft mounted rockers.

Requires special pistons.

Heads are sold individually.


Material: RMR Cast

Aluminum Alloy

Valve Angle: 20° 

Intake Port Volume: 451cc and CNC

Intake Valve: 2.400”

Exhaust Valve: 1.800″

CNC Chamber Volume: 97cc

Intake Port Shape: Rectangle

Exhaust Port Location: .500” raised

PRO1 20° CNC – Aluminum

19775090 – Bare head

19775196 – 1.625” Dual Springs for Hydraulic Roller or Solid Flat Tappet Cam .850”

19775199 – 1.650” Triple Springs for Solid Roller Cam .900”

PRO1 20º Tech Sheet – H39