Our 408 big-block (402 with an .080-inch overbore) was machined by Bad Attitude Engines an
Well, the day of reckoning finally came. Our “small” big-block was ready for the dyno. We’d finally see if the stuff we picked out made for a good combo of horsepower and torque for the street, while staying fairly budget friendly when it comes to big-block builds.
With our 4.185-inch bore and stock 402 stroke, we have a total of 408 cubic inches. The heads are factory 820 oval ports, with enlarged valves and some port and bowl work. Our net compression is right around 10:1, still pump gas friendly, and when we try out some aluminum heads later on, we can manipulate chamber size for a boost in compression, but still stay pump gas friendly thanks to the alloy heads. But that’ll be later in this engine’s life.
We made five runs total, with all the data presented here. Our intake is the factory cast iron, 360 HP 396 intake for the ’67 model year, our ignition a single points type, and most everything else as original as possible. We know there’s a lot more to be had from the 408, but we wanted to leave more on the table so we’d have more stories to write for the magazine later on. And for the guys who want more power but also want to keep a factory stock appearance, this build can be used as a road map to build a similar engine. Total cost (sans carb): $4,282.95.