How to Build Killer Chevy Small-Block Engines. Mike Mavrigian
| Small Journal Cranks | ||
| CI | Mains | Rods |
| 265 | 2.300 | 2.000 |
| 283 | 2.300 | 2.000 |
| 302 | 2.300 | 2.000 |
| 327 | 2.300 | 2.000 |
| Medium Journal Cranks | ||
| CI | Mains | Rods |
| 262 | 2.450 | 2.100 |
| 267 | 2.450 | 2.100 |
| 302 | 2.450 | 2.100 |
| 305 | 2.450 | 2.100 |
| 307 | 2.450 | 2.100 |
| 327 | 2.450 | 2.100 |
| 350 | 2.450 | 2.100 |
| Large Journal Cranks | ||
| CI | Mains | Rods |
| 400 | 2.650 | 2.100 |
Thanks to the research and development of aftermarket block manufacturers, we no longer need to rely on aged OEM blocks. Quality blocks, such as the Dart iron block shown here, offer superior metallurgy, improved priority main oiling, and precision casting.
In the early days, performance builders began using the 400 engine’s 3.750-inch stroke crank in 350 blocks to increase displacement of the 350, along with enlarging cylinder bores to 4.030 inches (383 ci), which required align honing the main bores to accommodate the larger 400 cranks. Also, while the 350 platform required internal crank balancing, the 400 crank required an external balance with a balance-weighted damper and flywheel.
Starting in 1998, NASCAR applications began using the SB2, which is essentially the second generation of the original SBC. The basic difference lies in the cylinder heads, which feature an altered valve layout, 11-degree valves, and an 8-bolt valve cover instead of the traditional 4-bolt pattern. A popular build involves 440 ci with a 4.000-inch stroke, 4.185-inch bores, and 15:1 compression.
Forced induction along with stronger bottom-end components raise the bar in terms of potential power. This twin-turbo SBC is a prime example.
In addition to the incredible array of components designed to enhance performance, the SBC is one of the most versatile platforms for visual customization.
NASCAR’s SB2 is essentially a small-block Chevy with different cylinder heads that feature 11-degree valves, an altered valve layout, and 15:1 compression. (Photo Courtesy GM Media Archives)
Today’s Options
Today, aftermarket cranks with a variety of stroke dimensions and choices of rod and main journal diameters are readily available for the 350 platform. This allows builders to achieve just about any displacement desired with the added advantage of superior-strength forged crankshafts. With the advent and continuing development of superior aftermarket blocks, cranks, bearings, rods, pistons, heads, cams, rockers, stronger high-grade main caps, rod and head fasteners, pushrods, intake manifolds, carbureted and injected fuel systems, and advanced ignition systems and oil delivery, the need to make do with OEM components has been eliminated.
Engine building machinery has evolved by leaps and bounds over the years in the pursuit of not only efficiency but also high-precision results from cylinder bore and lifter bore corrections to main bore sizing and alignment, bore honing, crank balancing, cylinder head seat and guide work, head porting, and beyond.
For applications that plan to use a crank-driven supercharger, small-block aftermarket cranks are available with longer, larger-diameter big-block snouts to accommodate the added stress. Many choices are available in terms of component design depending on the final goal, such as shorter-angle cylinder heads, larger valves, rocker arms of various ratios, valve springs of various metallurgy, design and rates, lightweight titanium retainers and valves, connecting rods in steel or aluminum, lightweight crankshafts with profiled counterweights, both wet and dry sump oiling systems, superior wet sump oil pumps, stronger and more precise timing systems, etc. The list goes on. There may be no other engine platform that has benefited from persistent, ongoing, and never-ending development than the stalwart small-block Chevy, and there appears to be no end in sight.
Superior ignition timing is available by referencing directly from the crank via flying magnet crank trigger systems.
The small-block, especially the 350 platform, has become, in essence, the performance industry version of a Lego set. If you can imagine it, you can build it, all thanks to the efforts of early to present-day racing engine builders and the spectacular support of the entire automotive performance parts aftermarket.
Whether for a racing application or for powering a custom street rod, the small-block Chevy remains one of the most popular choices.
The increasingly common use of CNC machining allows block blueprinting on a single machine, something unheard of in days past.