In the beginning, we intended to build a lumpy-sounding big-block that would rumble the pavement while it cruised the fairgrounds of the Western United States. What we ended up with was one shag nasty mega motor that not only shakes the earth, but also produces some mighty impressive horsepower numbers as well. In doing so, we made careful parts selections, like with all build-ups. To further the cause, we called in the folks at Speed-O-Motive to help coordinate and assemble this new 540-inch monster. Keeping its intended purpose (and supercharger) in mind, we arrived at 8:1 compression. Everything went according to plan, as the Speed-O guys quickly showed us their capabilities. This shop builds lots of engines, powering everything from restorations to racing and marine applications.
Once the parts pile was complete, things progressed at a rapid rate, thanks to Speed-O-Motive's state-of-the-art machining department. And through the build-up, we only experienced one bummer-the brand-new DTS dyno was still being plumbed and wired, so we had to quantify the numbers out at the Vrbancic Brothers shop, located about 30 miles east of Speed-O-Motive. No big. Check it out, as we go through the build-up sequence and you're sure to see why this monster shakes the pavement.
 During the prep and machining...  During the prep and machining process, Speed-O-Motive clearanced the bottom end for the Scat stroker crank, bored the cylinders (from 4.250 to 4.500 inches), and align-bored the Dart "Big M" block (PN 31273344). |  Though everybody might have...  Though everybody might have his own preferred method, proper cylinder wall cleaning is paramount to a successful engine build. Charlie Presby, our assembly pro, relies on lacquer thinner for this final clean-up chore, which is available at most any hardware store. Notice the lifter valley area, painted with Glyptol, for more efficient oil return. |  Dart supplies its own special...  Dart supplies its own special cam bearings, which feature improved oiling characteristics, as opposed to "off-the-shelf bearings." Once a generous amount of the slippery stuff was applied to the bearings, our Lunati (PN 50256) cam was installed. The specs are: .804-inch lift (intake), .755-inch (exhaust) with a 1.7:1-ratio rocker arm. The duration numbers are aggressive, with 285 degrees duration (at .050-inch tappet lift), and 295 degrees (also at .050) on the exhaust side. Lobe separation is 114 degrees and total advertised duration is a rumpity 326 (intake) and 338 (exhaust). |
 We're using a Scat 4340 stroker...  We're using a Scat 4340 stroker crank (PN 4-454-4250-63), similar to those used in motors producing over 1,200 hp. This crank features mirror-polished journals, smooth counter-weight edges (for minimum drag), and large chamfered oiling holes. The Scat journals ride on Federal-Mogul main bearings (PN 141M). |  Charlie torqued the ductile...  Charlie torqued the ductile iron rear main bearing cap to 105 ft-lb before checking the crankshaft end-play (.002-.006-inch is recommended). |  Mounting pistons to the Scat...  Mounting pistons to the Scat 4340 H-Beam rods (PN 245463852200) can be an exercise in futility, if you've never messed with Spiro-Locs. These spring-steel babies are difficult to work with, but do provide a positive way to lock the pistons to the pins. As shown in the photo, Spiro-Locs have to be spread apart and worked into a receiver groove, bit by bit. Charlie used Clevite assembly lube (or "red grease") on the pins, to help ensure that the floater pin doesn't seize. Note: Installing them is much easier than removing them! |
 After checking the JE Plasma...  After checking the JE Plasma Moly "file-to-fit" rings (PN J100F8-4500-5) in each bore, ring end gap was set to .027-inches, and filed one by one. Speed-O-Motive uses this cool tool, which combines an electric motor, grinding wheel, ring vise, and dial indicator all in one handy unit. |  Just like Spiro-Locs, piston...  Just like Spiro-Locs, piston rings can be stubborn, too. Once they're all in place, Charlie's preferred method of ring positioning is: top ring facing top of block-second ring facing down-oil ring separated 90-degrees (right and left). When we asked what the most important benefits of proper ring positioning were, he said, "Ring placement is critical, because proper alignment will help keep heat off the piston itself, and away from the top ring." |  Clevite H-Series rod bearings...  Clevite H-Series rod bearings (PN 8-7200CH) were used. Again, when we asked Charlie about the benefits, he said, "They offer a harder, more durable composition, which helps them handle the internal pressures of a blower motor." |