Torque to me, baby. When the digital twist-o-meter reads out 640 lb-ft at 4,100 rpm, some type of supercharger is usually involved. But not with this 505ci wedge. Combine that normally aspirated grunt with 583 hp and you have a bitchin' street engine.
The password to enter the bad-boy world of big-inch street motors is "stroker." While everyone always wants to talk about horsepower, the big-block Chrysler wedge engines have enjoyed a long history of stout performance based on their excellent torque numbers. And the easiest way to make even more torque? Just add displacement. That led us to a question-what would happen if we stuffed a longer arm in a 440 RB engine? Our candidate started out as a '71 Dodge 11/42-ton truck motor found cast away at our local Pick Your Part recycling yard. After $130 changed hands, we soon had the greasy short-block cleaned up and ready for a stroker crank to up the inches. A stock 440 combines a sizeable 4.320-inch bore with a tiny 3.75-inch stroke to produce 440 cubes. Tom Lieb, the owner of Scat, saw this as a wonderful opportunity to put a ridiculous 11/42-inch additional swing on the crank to create a 4.250-inch stroke that along with a 0.030-inch overbore would push the displacement needle just past the magic 500ci mark to 505. How cool is that?
To ensure that Federal-Mogul bearings live a long and happy life, the key is precision measurement. Engine builder Taylor strives for a little over 0.002-inch clearance for both the rods and mains for a street engine that will not see excessive rpm.
What we created was nothing short of a torque monster. At 3,500, the first test with an Edelbrock Performer RPM intake made so much grunt the dyno couldn't hold it. With a little tuning, this beast made 640 lb-ft at 4,100 rpm, and the lowest we could pull the dyno was 3,500, where it twisted up 614 lb-ft. The horsepower wasn't as impressive at only 562, so we added an Edelbrock Victor single-plane and watched the horsepower jump to 583 at a mere 5,700 rpm, while losing almost no torque with a peak of 634 at the same 4,100 rpm. Check out how it all went down.
RB Block Building
You would think that stuffing a 1/2-inch-longer stroke crank in a motor would require hours of grinding and a lifetime subscription to Iron Lung Monthly. But the truth is, the Scat rotating assembly was one of the easiest parts of this assembly. Scat chose to use off-the-shelf 6.700-inch big-block Chevy rods combined with JE forged and dished pistons to complete the rotating assembly. Engine wrangler Ed Taylor took on the job of putting it together after Jim Grubbs Motorsports performed its usual precise machine work, which included magnafluxing or boring and torque-plate honing to 0.030-over, align-honing the stock two-bolt mains, and then configuring the deck to get it as close to square as possible.
Final short-block assembly involved installing the ATI balancer. Always use a balancer installer tool. Leave the 10-pound sledgehammer in the corner of the shop where it belongs.
Oil System Details
Most production engines have fairly bulletproof lubrication systems that can be used with great success even for high-output situations. The 440 Mopar needed a little attention in this area. We went with a complete Milodon oil pan, windage tray, and single-line, remote-fed pickup assembly that required some extra work.
The Induction And Exhaust
Displacement is the easiest path to making torque, and since we weren't out to make this engine spin very fast, the original-design Edelbrock Performer RPM aluminum 440 heads were the choice. The intake and exhaust ports are both in the stock location as opposed to the Edelbrock Victor heads, which offer more flow but also raise the exhaust port by 1/4 inch, adding expense for custom headers. For the first test of this engine, Taylor assembled the engine with an Edelbrock Performer RPM dual-plane, but we also brought along an Edelbrock Victor 440 single-plane to evaluate the differences in the power curve.
The piston and rod are a full-floating combination that uses these double Spirolocks to keep the wristpin firmly located in the wristpin bores. The piston has an inverted dome with a 19cc dish. | 
Taylor checked the crankshaft endplay to ensure that the crank wasn't too tight in the block. Shoot for around 0.005-inch for thrust-bearing clearance. |
Scat has dialed in the combination of a 4.250-inch-stroke 4340 forged steel crank, big-block Chevy H-beam 4340 steel rods, and a set of dished JE forged pistons into a complete rotating package that is already matched to make balancing easier. | |