 We happened to have a forged...  We happened to have a forged 273 crankshaft residing on the shelf and figured this was a good time to put it to use, so the switch was made from the factory cast iron piece. The crankshaft was balanced and we began assembly. |
 Our Keith Black (PN 167) pistons...  Our Keith Black (PN 167) pistons were hung on the rods at Precision, so all we had to do was install the Federal Mogul moly rings and bearings, and the assemblies were ready to meet the block. |
 With the pistons in the bores,...  With the pistons in the bores, we checked the deck clearance at each hole and found them right on zero. |
 A Comp Cams 280H Magnum hydraulic...  A Comp Cams 280H Magnum hydraulic flat-tappet camshaft was our choice in looking for the elusive 400hp number with our 318. The 280H is a stout street piece, but tame enough to live with. The Comp hydraulic lifters, like most aftermarket pieces, have provisions for pushrod oiling. |
 Magnum heads, with their closed...  Magnum heads, with their closed chambers, good flow, and awesome bang for the buck, were the best choice for our particular combination. With the help of correct Magnum head-bolts, we torqued the heads in place. Magnum heads use different bolts than the LA-series heads. |
Starting at the bottom, the contents of the block had to work together optimally in order to reach our goals. Piston choice is a critical aspect of any build, and in the case of the 318 the choices are limited. Our requirements were a flat-top piston at zero deck, which would provide a desired boost in compression ratio, while also ensuring that we would have an ideal quench clearance to make the most of combustion efficiency. Stock and stock replacement pistons place the pistons so far down the hole, that even with massive milling, the goal of a zero deck is out of reach. Fortunately, Keith Black offers a hypereutectic 318 piston that fits our criteria (KB 167). The assembly can be brought to zero deck with modest block machining, and the pistons are a commonly available shelf part at a practical price. To provide the combustion seal and desirable friction characteristics, high-quality moly rings are needed. We looked no further than Federal Mogul's offerings, opting for their pregapped moly rings. Though file-fit rings can be had for our bore size, these rings are more in keeping with our requirement for moderate cost and a bolt-it-together assembly.
A zero-deck block is a waste of time without a closed-chamber quench head to go along with it. While practically all high performance aftermarket heads are of this configuration, we sought to reach our goals without the expense of aftermarket aluminum heads. Looking at the production options, the field is limited since the vast majority of stock small-block heads were of the open-chamber variety. The only exception in the LA-series heads are the closed-chamber, late-model, 318 two-barrel 302 castings. The ports and valves in these heads do not offer sufficient flow to meet our goals. With serious porting and larger valves installed, the 302 heads could get us there, but these mods are contrary to our goal of a bolt-together package. However, the later Magnum heads also feature closed chambers, and with their 1.92/1.625-inch valve combination, these heads do have the flow to support 400 hp in the right combination. The Magnum heads offer numerous advantages in this application. With a chamber volume of 59 cc, these heads will offer about 10:1 compression ratio when combined with a zero-deck short-block utilizing typical .040-inch head gaskets. That's about where we figured we'd need to be to make the power number. The Magnum-head layout features excellent rockers with an added bonus of 1.6:1 in ratio, as opposed to the LA engine's 1.5:1. This aids our effort to reach the 400hp mark. Other Magnum pluses are lightweight, 8mm stem valves and machined valve-cover rails with ten valve-cover attachment bolts to minimize the potential for oil leaks.