Dart's cylinder head studs...
Dart's cylinder head studs employ this bull-nosed profile designed to bottom out in the fastener bore, producing the proper light interference fit on the block threads as the stud is tightened.
According to Lake and McAfee, no special dimensional tolerances are required when assembling the aluminum block. Main and rod clearances were set a touch on the fat side, in the 0.003-inch range, but that's their preferred oil clearance for all their buildups, especially when they don't know how the engine will be broken in. No special goops or procedures are employed for head sealing, either; just quality studs and a standard Fel-Pro gasket with aerosol gasket adhesive. Really, there is only one arguably trick component in the entire engine: the camshaft. Because the Dart block's cam journals are big-block Chevy in diameter, the cam is a custom-order piece.
Comp Cams supplied the stick, a hydraulic roller grind, on its 12-000-9 core. Lobe lift is 0.363-inch on the intake and 0.361-inch on the exhaust, while intake and exhaust duration at 0.050-inch lift are 236 and 242 degrees, respectively. Lobe separation angle is 110 degrees and the cam was installed on the 108 degree intake centerline. With Dart 1.6:1 rocker arms, net lift works out to 0.581-inch on the intake and 0.577-inch on the exhaust. So while the lightweight block requires a non-catalog camshaft, the cam timing used here is fairly conventional small-block fare.
Due to the wider pan rails, an OE-style oil pan won't fit. But not to worry; pans are readily available off the shelf from Moroso and others, in both wet- and dry-sump varieties. If you've opted for a wet-sump setup with a standard Chevy oil pump like this engine, you'll need to use a big-block oil pump shaft to compensate for the elevated camshaft centerline. A remote oil filter is also required since the block lacks a filter pad. And if you're running a block-mounted mechanical fuel pump, you'll need a 0.200-inch-longer fuel pump shaft, available from Dart. Finally, you'll need to machine a 0.391-inch spacer to slip between the intake manifold and distributor-again, to adjust for the increased cam height-or you can simply use one of the many adjustable-sleeve distributors on the market.
With a Fel-Pro 0.041-in. head...
With a Fel-Pro 0.041-in. head gasket, the compression ratio works out to 10.02:1-compatible with 87-octane pump fuel.
Once assembled, the aluminum small-block went straight onto Dart's Stuska-Depac engine dyno to test the results. There, the small-port combination did not disappoint: From 6,000-6,500 rpm the mouse did better than 500 hp, with a peak of 528 hp at 6,100 rpm. And perhaps even more impressive, there's more than 400 lb-ft of torque available throughout the engine's rpm range, from 2,000 rpm on up, with peak torque, 512 lb-ft, arriving at 4,800 rpm. This lightweight small-block is a little torque monster. And all this was achieved with a hydraulic roller cam, a single four-barrel carb, and 87-octane pump gas. Now there's real street performance you can use every day. Of course, there's another bottom line where this build is concerned. Here's the question everyone is dying to know: What does the aluminum small-block weigh? To establish a baseline for comparison, first we weighed a late-model, all-iron small-block in the standard Dart dyno configuration: complete, less flywheel, water pump, and alternator. Thus equipped, the cast-iron mouse tipped the scales at 476 pounds. Then we moved the heavy-metal lump aside and tossed the aluminum mill on the scale. In identical dress, the Dart aluminum V-8 weighed only 366 pounds. Light weight, solid driveability, and proven small-block performance make for a hard combination to beat.
What is it
400ci build with a Dart aluminum block
It's a reliable package that looks impressive under any hood
When OE-style hydraulic rollers...
When OE-style hydraulic rollers are not an option, the Dart guys like to use Comp Cams or Howard's lifters in their house buildups. These +0.300-inch long pieces from Comp require 6.900-inch pushrods in the high-cam Dart block.
Rocker arms are Dart house...
Rocker arms are Dart house label pieces (not yet in the catalog) with a 1.6:1 ratio. Valvesprings are 1.437 inch in diameter, the standard components on the Pro1 assembled head.
An all-aluminum Mouse motor...
An all-aluminum Mouse motor begins to take shape in Dart's engine assembly room. The cast-aluminum timing cover with integral timing pointer and the 7-inch SFI crank damper are by Engine Pro.
A Dart dual-plane intake manifold,...
A Dart dual-plane intake manifold, Demon 650-cfm carburetor, and MSD Pro-Billet distributor complete the combination. Secondary ignition wires are MSD as well.
With a standard distributor...
With a standard distributor housing a 0.391-inch spacer is required, or you can use a distributor that employs an adjustable sleeve to compensate for the Dart block's elevated cam centerline.
The best numbers on the dyno...
The best numbers on the dyno were achieved with out-of-the-box jetting on the Demon carb and 37 degrees of spark advance, all in by 2,500 rpm.
|*Corrected to 60 degrees F, 29.35 inches Hg