Affordable Small-Block Chevy - Special High-Performance Chevy Block

This cutaway of a production 400 block reveals how many 90-degree turns the oil must make to travel from the main oil galley and around the cam bearing to make it to the main bearings.

This cutaway of a production 400 block reveals how many 90-degree turns the oil must make

Hydraulic Roller Lifters
In the late '80s, Chevy altered the small-block Chevy with a one-piece rear main seal and also reconfigured the lifter valley area of the block to allow the use of hydraulic roller lifters. While GM retooled the small-block to attain slightly better fuel economy, car crafters have for years taken advantage of hydraulic roller cams for their performance advantages. Dart added this feature to its SHP block with all the production bosses in the lifter valley to retain the OE hydraulic roller lifters, along with milling the tops of all the lifter bosses so the OE retainers would seat properly. The front of the block is also machined for a factory hydraulic roller cam retainer plate. This means the block will require the factory-style nose on a hydraulic roller cam, so you don't have to waste time setting up camshaft endplay with a cam button. The lifter bosses are also taller to give more lateral support to the lifter, something that is lacking with older production blocks that are converted to hydraulic roller lifters. Of course, if you prefer to run a flat-tappet cam, the SHP block will also handle that with ease.

Special Features
There are several other important changes designed into the SHP block that deserve mention. As on any good high-performance block, the head boltholes are now blind, which means they do not project into the water jackets, thus eliminating a common small-block coolant leak path. Since this block was designed around the 400ci small-block, the pan rails and lower edges of the cylinder walls will easily accommodate a 3.75-inch stroker crank, but the same is true for the 4.00-inch bore block as well. The 4.00- and 4.125-inch bore blocks employ the smaller 350-style main bearing journal diameter to reduce bearing speed. Even though the block allows you to use stock hydraulic roller lifters like the newer one-piece production blocks, the SHP retains the two-piece rear main seal configuration to allow the use of a greater number of stroker crank applications.

Other additions include a complete boss assembly to mount a mechanical fuel pump (later roller cam blocks eliminated this) as well as that important pivot ball location that allows the use of a mechanical clutch linkage Z-bar. Plus, Dart added pads at the rear of the block that can be drilled and tapped to mount detonation sensors if needed. Of course, all the stock engine mount positions are drilled and tapped, and the SHP also accepts the standard spin-on oil filter and passenger-side dipstick.

By Dart Machinery

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