For our final test, we bolted on a set of RHS’ new Pro Action cathedral-port heads for LS applications. These new lungs, which use Clean Cast Technology to maintain more precise tolerances than are normally found in an “as cast head”, bumped our engine’s compression ratio up to 11.41:1 (due to its 62cc combustion chamber) and added a 225cc intake runner. The extra air and bump in compression allowed our transformed truck engine to really take off, recording 521 hp at 6,300 rpm, along with 476 lb-ft of torque at 5,000 rpm. If the engine is turned on, it’s making more than 400 lb-ft. That’s a total increase of 105 hp more than the carbureted stock long-block version, along with an extra 37 lb-ft of torque at the peak of a much fatter torque band. It’s also a 16 lb-ft and 26hp improvement over the stock lungs. This rejuvenated truck lump makes lots of useful torque throughout the powerband, and it now has a great top end. It should make for one snappy, fun-to-drive Chevelle. We’ll let you know.
Stuff to make it fit
Looking ahead, we had many of the pieces that we’ll need when this mill takes up its new residence under the hood of a ’66 Chevelle. One of these is Holley’s new LS Retro-Fit oil pan. According to Holley, this slick casting provides maximum chassis clearance for GM rear-wheel-drive applications, small-block or big-block, as long as it came with a rear sump oil pan. It also comes with a sump baffle, pickup tube, sump plug, oil filter stud, and an oil passage cover.