Description This is a well suited, lightweight and durable valvetrain solution for the F4R. The kit consists of single groove nitrided inlet valves, single groove Inconel exhaust valves and supertechs spring kit with Ti retainers. Valve Kit: These are a great starting point for any performance cylinder head build. High quality forged stainless valves are black nitrated for maximum hardness and smoothness. For the price, these are an excellent replacement for stock valves. The inconel exhaust valves offer far superior reliability to OEM style stainless, sodium filled exhaust valves which often crumble into the cylinder. These are all single groove keeper setups which are for extremely high rpm usage. This setup grips the actual shaft of the valve, rather then relying on the material of the three grooves itself to restrain the valve. Valve Spring Kit: An absolute must for anyone wishing to stretch the powerband of their engine out past 7500 rpm or so safely. These take a two pronged approach by increasing the spring rates meanwhile reducing the mass of the retainer, by using titanium. The use of titanium provides an adequate fatigue life to be acceptable for all but the highest mileage street use. These will allow usage up to 8000 rpm although we have used them for occasional use to 8500rpm on hydraulic lifters. More RPM is possible by converting to solid lifter buckets as there is plenty of spring rate here.
