The stock 1275cc Spridget and many later Mini Cooper heads have 1.31" intake, 1.15" exhaust valves and porting that means valve lift after about .350 is a waste of reliability! The heads supplied by Longman have huge valves: 1.48" intake and 1.15" exhaust valves. The porting is such that .500 valve lift is still on the curve of performance gains. This head not only works fantastic but looks like it belongs on display rather than in a car. The GT17 head from Longman is complete with extra long valves, special springs and rotators. These rotators help insure the valve is free to rotate as it goes up and down, thus greatly increasing the life of the valve seats.
Mini Mania is the exclusive direct importer of genuine Longman cylinder heads. As such we are also able to have heads modified to our specification, and we are directly involved in the ongoing development of the SCCA GT5 spec. head. All Longman heads are fully ported and polished and come assembled with Longman's exclusive valves, guides, springs and retainers.