New HRP Cams for Injected and Carbureted 4-cam style engines now in stock.

We have just received the first shipment of our new Billet cams in from the manufacturer. We have been working on design and testing several different cam combinations over the past 4-5 years with Legendary cam grinder Jim Leineweber and his son Justin. As a result, 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.

The carbureted cams (HR-E) have the larger cam lobes as well and gives .745 inches of valve lift with a 1.62 rocker ratio, and a bit more duration that our HR-1 cams that have been in our Derringer engines for years. The E cam grind is also available for our Gen-4 upgrade.

Contact HRP for more info.



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