The XR276HR offered a 0.502/0.510-inch lift split, a 224/230-degree duration split, and 110-degree LSA. A good portion of the extra power came from the cam upgrade, a Comp Cams XR276HR hydraulic roller cam. The same dual-plane intake and a Holley 750 HP carburetor topped the AFR heads. For this application there was no need to step up to the Competition package, but the Eliminator heads featured 65cc chambers, a 2.05/1.60 valve package, and flow numbers to support over 550 hp. The basic short-block remained the same, but the 355 received a new set of AFR 195 Eliminator heads. Off came the 100hp upgrade parts and on went a new set of heads and induction system. Though we could get away with using the as-cast RHS heads at this power level, we decided to try a whole new combination. The first 100hp increase was easy, but each successive jump in power becomes more and more difficult. This trend continued with each successive step up in power. Note that the engine produced peak power and torque higher in the rpm range compared to the two-barrel configuration. The mildly modified Mouse pumped out 347 hp at 5,400 rpm and 399 lb-ft of torque at 3,700 rpm.

Topping the as-cast RHS heads and RV cam was a Speedmaster dual-plane intake and Holley 650 HP carb. Working with the 180cc RHS heads was a mild Comp High Energy 252H cam that offered 0.425-inch lift, 206-degrees of duration 0.050) and 110-degree LSA. Though this power level would easily be served by a set of ported stock or Vortec heads, we stepped up to a set of as-cast Pro Action aluminum heads from RHS. Toss in a mild cam and cylinder head upgrade and the power gains really start to add up. Replacing the 2G with a Q-Jet and intake alone can be worth 25-30 hp. The first 100 hp is the easiest since every component on the stock two-barrel engine is restrictive, starting with the diminutive carburetor. Obviously, coaxing more power out of a two-barrel 355 isn't particularly difficult, especially given the vast array of performance products available.

Cam 350