Dart 18° aluminum small block cylinder heads offer a dramatic performance improvement over conventional 23 degree designs. By reducing the valve angle, reshaping the intake ports, and optimizing the combustion chambers, we produced a significant increase in both airflow and combustion efficiency and that means more power!
Dart 18° heads use the same readily available components as other 18° designs. The difference is that Dart delivers the features that put you ahead of the competition. We've refined the 18° design to give our customers more versatility, more performance, more reliability, and higher quality. Dart 18° heads are a step ahead!
Intake and exhaust ports can be fully CNC machined and seats prepared with competition valve job for maximum flow. Race ready assemblies include stainless steel valves, 1.550" dual springs, 10° titanium retainers and locks, rocker studs, hardened pushrod guideplates, valve seals, and spring seats.
Material: High density 355 T6 aluminum Valve Angle: 18° Intake Ports: 237cc as cast; 257cc with CNC full porting Exhaust Ports: 104cc as cast; 108cc with CNC full porting Combustion Chambers: 67cc as cast chamber volume, 69.4cc with CNC full porting (can be reduced to 48cc by milling deck) Intake Valves: 2.150", 2.180"; +.600" long Exhaust Valves: 1.600", 1.625"; +.600" long Guide spacing: Standard 1.935" or 1.955" "wide guide" (recommended for 4.125" and larger bore) Valve Guides: Replaceable magnesium bronze (for high compression), phosphorous bronze (for 9:1 compression); 11/32" I.D. Rocker Arms: Requires Jesel or T&D shaft rockers Shallow combustion chamber design improves combustion and allows use of larger valves for improved airflow. 67cc as cast chamber volume can be reduced to 48cc by milling decks. Interlocking ductile iron valve seats are compatible with stainless steel and titanium valves. Valve seats will accommodate up to 2.180" intake valves and 1.625" exhaust valves to maximize flow. Valve centerlines are available with standard 1.935" or 1.955" "wide guide" spacing for optimum valve locations with different bore sizes. Spark plugs are shifted toward bore centerline to enhance flame travel and reduce spark advance requirement. Refined intake port design reduces turbulence and improves airflow. Tall short side radius and deep valve bowl enhance low-lift flow. Extra thick decks for 9:1 engines can be milled for high-compression engines. Dual exhaust bolt patterns are drilled for standard 18° and spread port header flanges. Water passages between exhaust ports improve cooling and prevent "hot spots" that can cause head gasket failure. Integral bosses can be drilled for fuel injection down nozzles. 