Like any good cliff-hanger, when we left you last month, our Anti-LS small-block engine was well underway at Dart Machinery. But would we be able to do what we set out to? Could we build a Gen I small-block Chevy that could run with the new favored-son LS engines? Would it be streetable? Dependable? Would Charlie finally ask Diane to marry him? Wait, wrong soap opera.
We reconvened with Jack McInnis, Tony McAfee, and Jeff Lake at Dart to finish the build and dyno test the small-block to see if we had a winner, or wishful thinking. Last month, the crew at Dart machined and assembled a stout SHP short-block as the foundation for our anti-LS engine. Using the company’s iron SHP block with a 4.000-inch bore, they tossed in a 3.750-inch Eagle crank, CompStar steel H-beam rods, Mahle flat-top pistons and a COMP Cams solid-roller camshaft.
We detailed the components...
We detailed the components and assembly in this Dart SHP 427 short-block last month. In case you missed that, the CliffsNotes version is that it’s an all-new cast-iron block with clearance for a 3.750-inch stroke with steel rods and up to a 4.125-inch unfinished bore. Ours has a 4-inch stroke Eagle 4340 forged steel crank, CompStar H-beam steel rods, and Mahle forged flat-top pistons.
With 427 ci in the short-block and a camshaft worthy of its solid roller construction, this engine needed a pair of cylinder heads that could deliver a healthy volume of air/fuel mixture. We had two additional requirements for the cylinder heads. First, they needed to be a traditional 23-degree design with stock valve and port locations. That way a regular intake manifold and headers would bolt up; in fact, the whole exhaust system that is already in our Laguna should reattach nicely. Second, they had to flow like tax dollars into the national debt right out of the box. By avoiding hand porting, we’re building an engine that you can duplicate exactly with off-the-shelf parts. You can thank us later. The Dart Pro 1 CNC heads were exactly what we were looking for. They are fully CNC machined for precision, and the intake ports are a massive 227 cc. At .700-inch lift, the intakes will flow 309 cfm, and we’re in that ballpark at .688 inch of lift at the valve with our COMP Cams roller camshaft and 1.6:1 rocker arms. The exhaust side is matched proportionally to the intake, with 226 cfm at .700-inch lift.
For the most part, the valvetrain in this 427 is made up of COMP Cams matched components. We like this approach because the cam manufacturer generally has a good matched set of valvesprings, and all of the related parts such as lifters and pushrods are designed to play nicely with each other. The only valvetrain parts that are not from COMP are the 2.08/1.60-inch valves and adjustable guideplates, which all came from Dart.
We introduced you to our custom bumpstick last month, but the specs merit repeating here. The intake lobes sport 259 degrees of duration at .050-inch lift while the exhaust side has 268 degrees. Lobe separation is 108 degrees, and lift on both lobes is .430 inch, which gives us a gross lift of .688 inch with the COMP Cams Ultra Pro Magnum 1.6 rocker arms. This camshaft is aggressive for the street by most people’s standards, but this engine isn’t meant to be a docile, smooth idle, high-vacuum and otherwise yawn-inspiring small-block. We’re pushing the envelope of streetable power and with that comes a higher, rougher idle, and getting intimate with the fine line of durability. This engine won’t require a ton of maintenance, but checking the valve lash twice a year will let you know if any of your valvetrain parts are wearing and need attention.
The Dart SHP block has rod-clearance...
The Dart SHP block has rod-clearance notches for big stroke applications, and it locates the dipstick on the passenger side, which means that many of the most popular performance oil pans won’t fit. We had a Moroso kick-out pan on our last engine in the Laguna where this engine is destined. Moroso is in the process of building an oil pan for this application and should have it available about the time you’re reading this article. Jeff Lake at Dart measured the pickup tube height to make sure it would work with the oil pan that will be used during the dyno test.
To button up the bottom end,...
To button up the bottom end, we ordered a Moroso oil pan and oil pump. When you order a pump and pan from Moroso, the pickup tube comes welded to the pump so all you have to do is install the mounting stud and torque the pump in place. The Dart block has an extremely good flowing oil system, so a standard volume/pressure oil pump is recommended to keep from emptying the oil pan. The all-metal driveshaft and mounting stud are also included, although we swapped the stud and nut out for ARP components to be consistent with the rest of the engine fasteners.
We chose a TCI Rattler 2000...
We chose a TCI Rattler 2000 damper for this engine build. The Rattler is designed to absorb torsional vibration with an internal pendulum absorber. It doesn’t have any components that will wear or age, so it requires no maintenance or periodic rebuilding. It’s also one of the lightest dampers available.