Dart Iron Eagle cylinder heads will give you the performance you want at a great price. They feature thick port walls (extra meat for porting!), enlarged water passages, multi-angle intake valve seats, hardened and radiused exhaust valve seats, bronze valve guides, and heart-shaped 64cc or 72cc combustion chambers. They are available as bare castings or fully assembled with stainless steel valves, valve springs, locks, and retainers.