How to Build a Small Block Chevy for Low End Torqueby Richard Rowe
From daily commuter to full-race, there are literally hundreds of different ways to build a small block Chevrolet. While neophytes might be tempted to simply drop the biggest heads on the motor and stab in an enormous cam, real gearheads know that peak horsepower alone won't win you anything but an internet forum argument. Horsepower numbers are impressive, but the fact is that you drive on the strength of your engine's low-rpm torque. Building a small block heavy with tire-shredding force isn't particularly difficult, provided that you start with the right foundation.
Acquire any Camaro/Corvette Tuned Port Injection (TPI) 350 V8 produced since 1985. Complete engines aren't expensive or hard to find; just make sure that you get the entire engine including the heads, upper/lower intake and sensors. GM made a lot of changes to the TPI small block during its production run, so parts from one engine won't necessarily interchange with another one from the same model year.
Tear the engine down and rebuild it using any of the commerciallyavailable 383 stroker kits on the market. These kits will include a new crankshaft and rods, and can also include everything from bearings to pistons if you specify them. You don't necessarily need to use forged pistons or rods, but they can't hurt and will give you the option of running nitrous for more horsepower. Install a set of pistons with about 10-to-1 compression.
Perform a mild porting job on the heads. At the very least you'll want to use a die grinder to gasket-match the intake ports to the intake gasket and to blend the valve seats into the cylinder head. These gasket-matching and bowl-blending procedures are always good for more flow at lower valve lift, which is what helps to build torque.
Send the upper and lower intake to a shop that specializes in extrude honing. Extrude honing involves shooting large amounts of abrasive material through the ports at very high pressure, enlarging and smoothing them. Extrude honing isn't cheap and it's not something you can do yourself, but it's absolutely necessary if you want the TPI intake's relatively small runners to feed your 10% larger displacement.
Slide into the block a camshaft with about 214/220 degrees of intake/exhaust duration at 0.050-inch valve lift. Valve lift should be about 0.452-inch intake and 0.465-inch on the exhaust; a 112-degree lobe separation angle will work best for this application. Install an aftermarket dual-spark distributor. The stock computer doesn't have a wide enough tuning envelope to accommodate the extra displacement, so use an aftermarket fuel management unit to control the spark and fuel.
- An engine built to this spec should produce a respectable 350-plus horsepower at about 4,700 rpm and a massive 470 ft-lbs of torque at 3,400 rpm. Fuel economy should be fairly decent for a nearly 400-cubic-inch engine, especially if you use an overdrive transmission to keep engine speed low. Idle quality and engine vacuum should be near-stock.