Before sliding the pistons...
Before sliding the pistons and rods in the bores, Mitchell filed the ring gaps to size. Since the 383 won’t see any nitrous, he set the top ring gap at a tight .020 inch, which works out to .0049 inch per inch of bore. The second ring gap was set at .018 inch.
The final link in buttoning the 383 up was selecting the valvetrain hardware, and once again we kept things as simple as possible. To that end, Summit set us up with one of its flat tappet cam and lifter kits, which lists at $134. The cam of choice features 246/246 degrees of duration at .050, with .500/.500-inch lift and a tight 108-degree lobe separation angle. While the duration specs might seem a bit aggressive for a 383ci combination, the motor’s healthy 10.2 compression ratio helps tremendously in terms of retaining low-rpm cylinder pressure and preserving driveability. Furthermore, opting for a flat tappet grind cut down on costs significantly.
What’ll She Do?
With most 383 builds, it’s...
With most 383 builds, it’s usually necessary to notch the bottom of the cylinders to prevent rod-bolt-to-block interference. Scat’s Pro Stock I-beam rods incorporate a slender, low-profile design and ARP 7/16-inch capscrews to increase clearance. Mitchell simply tapered the head of the capscrews, and no clearancing of the block was required.
Since the very nature of budget-oriented engine builds is making respectable horsepower on the cheap, there’s always a bit of tension when strapping an untested combination to the dyno. Fortunately, our concerns were unfounded. With Outlaw’s Andy Mitchell doing the tuning and Westech’s Steve Brulé pulling the handle, the 383 served up 446 hp at a very street-friendly 5,900 rpm, and 474 lb-ft of torque at 4,000 rpm. Disproving any suppositions that our 383 is overcammed, it produced a stout 454 lb-ft at just 3,500 rpm. With a hydraulic roller cam of similar duration in lieu of our flat tappet unit, it’s conceivable that the 383 would have netted an additional 15-20 hp. Throw in a solid roller, and another 15-20 numbers on top of that is entirely feasible. Nonetheless, our budget 383 exceeded all expectations, proved extremely easy to assemble, and should provide tens of thousands of miles of hot rodding fun.