396 Torque MonsterIf you're an avid Chevy High reader, we're sure you'd relish the chance to get a bankroll of $5,500 to build your own small-block to your specs. For this opportunity I decided to build something other than what we've built over the last few years. The target performance range of this motor is something that will easily produce lots of torque and work very well in a street-driven performance car. That meant a completely different displacement, a not-so-often-tried camshaft, and a set of low-cost aluminum cylinder heads. The shop I chose to accomplish this engine build was Larry's Performance in Montebello, California.
For many, the term 396 conjures up thoughts of a stout big-block Chevy, but in this case all 396 ci are stuffed into a four-bolt-main 350 Mouse block. This buildup started with a well-worn '79 Chevrolet small-block casting that had been pulled from a half-ton truck and bored 0.030-inch over to achieve a 4.030-inch cylinder. The large displacement from the 350 motor is achieved by axing the stock 3.48-inch stroke crank and replacing it with a 3.8750-inch forged-steel shaft fitted to a set of 6.00-inch I-beam full-floating rods and SRP forged pistons. Yes, this means a very short 1.062-inch compression height on the pistons.
To support the midrange power goal of this combination, an Isky 292 Mega cam with 505-inch lift, 244 degrees of duration (measured at 0.050-inch lift), and 108-degree lobe center got the nod. The ignition system is a proven MSD unit and MSD ignition wires. Then a set of aluminum cylinder heads to help lighten the load and a Professional Products dual-plane intake topped off the package to provide good engine performance within the budget.
When we had finished we were rewarded with a big 481 lb-ft of torque on the dyno and almost 440 horses. Yes, big power for little money.
The secret of this large-displacement engine is the forged-steel crank with 3.8750-inch stroke, which translates to a 0.395-inch increase in stroke. Thoroughly clean any crankshaft before installation (even if new).
After installing all the main bearings and measuring the clearances, the long-stroke crankshaft was dropped into position.
For good midrange power we added an Isky 292 hydraulic Mega Cam. This bumpstick is ground on a 108-degree lobe center and has 0.505/0.505-inch lift. Key to proper cam installation is the addition of the manufacturer's lube. This provides adequate camshaft lubrication during the first few moments of engine operation, before engine oil reaches each lobe.
The pistons selected for this 396 small-block are full-floating SRP forged items connected to 6-inch I-beam rods.
Each piston and rod assembly is quickly pushed into the bore with the help of a ring compressor seated squarely to the deck of the block. To do this properly each respective crank journal must first be placed at bottom dead center.
With the reciprocating parts installed we measured the deck height. This configuration provided 0.015-inch above the piston at TDC.
Each connecting-rod side clearance measured about 0.020-inch.
To secure the heads to the motor we first applied the appropriate lube and torqued our ARP head bolts to 65 psi.
With the short-block together we installed the aluminum cylinder heads provided by Larry's Performance. These heads have 195cc intake ports and 2.02/1.60-inch valves.
Included with this engine package is a full set of 1.5 stainless roller rocker arms.
To help our midrange power goal we added a Professional Products dual-plane intake manifold. To ignite the motor we also installed an MSD ignition system.
Together and on the dyno took in a matter of days. The carburetor we chose for this combination is a Barry Grant 750-cfm Mighty Demon. Before our initial start-up we added 5 quarts of Rotello 15-40 engine oil for proper camshaft break-in.