Precise reproductions of stock Knucklehead cylinder heads, cast from aluminum. Besides the significant weight savings of approx. 4 kg per head they dissipate heat much better than their cast iron counterparts. They are manufactured after 1940-1947 heads with large intake ports. The valve seats are pre-installed, but unmachined and sized for stock intake and exhaust valves. They are hardened for the use of today’s unleaded fuels. Steel inserts for the head bolts feature factory threads. The heads show all the small details like cast-in number tags and foundry markings, so they make for excellent stock replacements or for building a performance engine with factory look when you camouflage them with black paint.