We now have a new grind for the 4-cam engines running the 86-90 XL style set-up. This includes the Overkill, PRP, our Derringer engines and others the use the 4-cam valve train. The injected cams (HR-J) are designed for 150 - 200 cubic inch Nitro engines. Improvements include a much larger diameter cam lobe that improves lifter roller to cam lobe contact. This design also allows the cam manufacturer more flexibility in designing the profile of the lobe. We spent many hours designing and testing our new injected grind with the main objective to relieve some of the extreme exhaust pressure the exhaust valve has to open against. This is the main reason for pushrod, lifter and rocker arm failure in these engines. The larger lobe diameter has allowed us to do that so the valve train has it a bit easier opening the exhaust valve. Valve lift is .865" with a 1.74 rocker ratio.