One of the high points in the development of the small-block Chevy engine, and a cornerstone in its reputation as a bulletproof power producer, is the legendary LT-1 introduced in 1970. Available as a regular production option in Corvettes that year and the following two years, the LT-1 featured a long list of power magnifying and durability enhancing features. Four bolt main bearing caps held a secure grip on the forged crankshaft. Forged aluminum pistons were pinned to forged steel rods. A generously timed camshaft, solid lifters, large valves and a 2 1/2-inch exhaust system enabled the engine to breathe freely right up to its 6500 rpm redline. An 850-cfm Holley perched atop an aluminum intake did the fuel delivery chores while a high-volume oil pump downstairs took care of lubrication. The fire in each cylinder was lit by a dependable Delco transistor ignition system.
All of this added up to a 350-cid engine that delivered a conservatively rated 370 hp @ 6,000 rpm and 380 lb-ft of torque @ 4,000 rpm in 1970.
The following year horsepower fell to 330, largely as a result of a drop in compression from 11.0:1 to 9.0:1. This reduction was required for the engine to run on fuel with a Research Octane rating of no more than 91, which was the number the oil companies were predicting after they removed the lead from their gasolines.
In 1972, the final year of its availability in Corvettes, the LT-1 power rating was again reduced, this time more as a result of a change in the way the power was calculated rather than any real change in output. Previously, horsepower was measured at the flywheel with the engine on a dyno stand. The figure arrived at, called gross horsepower, reflected the engine's output when it was fed a steady supply of cool intake air and when it was unhindered by accessories like the alternator, fan, air cleaner, and so on.
Rather than reflecting gross power the 1972 figures indicated net horsepower (also called base horsepower.) Net power was a measurement of power made with the engine installed in the car, and the LT-1's lower number of 255 base horsepower reflected the considerable power lost to all of the engine driven accessories. In 1972, as in the previous two years, LT-1 Corvettes were true tire-churning musclecars, capable of low 14-second quarter-mile times in absolutely bone-stock condition. With headers in place of the factory's cast-iron exhaust manifolds and sticky rubber in place of the OEM tires, an LT-1 was suddenly a low 13-second quarter-miler.
In the early '70s big-blocks were still available in Corvettes and cars so equipped were measurably faster in acceleration and at the top end than a similarly equipped LT-1. But the LT-1 offered one important thing the big-blocks couldn't, namely superb balance. By paring more than 100 pounds off the front end, which is where Corvettes needed extra mass the least, the high-revving small-block made for a noticeably better handling and better stopping car. As an added bonus, the small-blocks tended to run cooler, and thus avoided the overheating problem the big-blocks tended to suffer from.