340 Big-Block Engine Buildup - Giant Slayer

Bench racing and jaw-boning had set us up with a lofty goal for our buddy Marko "The Rooster" and his 340 small-block. What started out as idle talk about building a 500-horse 340 while road tripping from L.A. to the 'Nats last year ended up as a plan to shoot for a big 600 number from Chrysler's performance small-block. While that would be enough to make his street/strip 'Cuda scoot, coaxing that much power from that many cubes is usually the realm of exotic, high-dollar parts. Conversely, we had a less-than-exotic stock 340 core, a set of good W-2s, a die grinder, and a plan. Making big power from small cubes takes airflow, rpm, cam, and squeeze; everything else is just there to help keep it together. With a tight budget for the power goals in mind, we had to limit the major expenditures to where it did the most good, and use what we could of the original 340.

We outlined the build of the basic long block in last month's issue ("Giant Slayer," May '02). A quick recap here-the basic combo started with a stock block, bored +.040-inch, and stiffened up with a partial fill of Moroso Block Filler. Nestled inside the factory main caps is the reground stock forged crank, clamped with Milodon studs. Eagle's budget I-beam rods got the nod for dollar value, while we shelled out for top-of-the-line Arias forged domed racing pistons and C&A Duramoly rings, because we didn't want to skimp in those areas. Up top went our own ported W-2s ("Porting The Magnificent W-2," Nov. '01), with Mopar's 2.02-inch/1.60-inch valves. A heavily discounted new MP tunnel-ram intake was carved to match the heads, and the basic combo was set.

While a fat roller cam would have been the ticket to high rpm power, a thin pocketbook meant "The Rooster" would have to scratch around for a flat-tappet to do the job. A custom-ground Competition Cams solid lifter cam-using one of Comp's extremely quick MM-series high-lift Mopar lobes on the intake and their XX series on the exhaust-seemed like it would do the trick. The MM-series solids aren't cataloged-it's a call-and-ask deal. We had ours ground with the 263 at .050-inch MM series on the intake, their 268 at .050-inch XX-series lobes on the exhaust, on a 108-degree lobe spread. A set of custom Smith Brothers pushrods working Crane's Gold 1.6:1 ratio rockers were ordered to open the valves. The bottom-end was buttoned up with a Milodon pump and sump, and that's where we left off.

Finishing It Off
With the basic package put together, it was simply a matter of dressing it out and running it to see how the power numbers stacked up against the mark. Carbs were a primary concern, since "The Rooster" was budget-bustin'. We found that ProForm carb bodies were available from Jeg's at a discounted price. A pair of these would offer bargain fuel mixing, since we knew of a well-used set of Holley 650 double-pumper cores we could score for parts. The ProForm bodies have a radiused-entry high-flow design, downleg boosters, and are rated at 750 cfm each. More importantly, they come with replaceable screw-in air bleeds, since air bleed tuning is a given when dialing in carbs for a high-rpm dual-quad tunnel-ram application. We went to Enderle for the linkage kit. Enderle builds a trick billet and spherical rod-end linkage setup specifically for the W-2. Though their broad range of kits are resold under many labels, they are surprisingly economical when dealing direct.