407 Chevy Small Block Engine - Street Scorcher Small-Block

That was just the plan Chris Henderson had in building a small-block Chevrolet for the AMSOIL Engine Masters Challenge. The idea wasn't to reinvent the small-block. Rather, Henderson makes the most of the best of what's already there. Henderson's philosophy is to pay attention to the details, and letting all of those small improvements add incrementally to a good basic package.

While it seems like this situation would create a difficult balancing act, the port size was largely determined by the intake manifold of choice, Edelbrock's Performer RPM Air-Gap. Henderson tells us, "My rod-to-stroke combo has a 1.6:1 ratio, which responds better to larger port volumes, with larger cfm carbs relative to the displacement. My ports are as big as I can practically make them with the intake."

The Build Starting with the production block, Henderson began with modifications to ensure the block's integrity at the expected high power level. The block was prepped with a partial fill using Moroso block filler in the water jacket, a move that increases the cylinder rigidity and also helps with piston ring seal. Eagle billet four-bolt main caps clamped with ARP studs add even more security to the lower structure. Prepped like this, the factory block can be very reliable at high power levels.

To further reduce the possibility of unnecessary windage-related power losses, the lifter valley was fitted with standpipes, and the oil drain directed to the front and back of the engine. Henderson says, "Up front with the Jesel beltdrive, there isn't anything for the oil to get caught up in; it's all smooth up there." Completing the rotating assembly, Henderson filled the bores with off-the-shelf Mahle domed pistons with a compression height of 1.125 inches, giving a compression ratio of 11.4:1.

At the valves, Henderson focuses on the exhaust valve configuration. Henderson favors a tulip profile valve form over the conventional nailhead valve. The theory here is that the tulip shape will help the flow quality out of the chamber, but the same valve will cost some flow. Henderson figures the trade-off is worth it, taking other measures with the camshaft, header, and a larger valve diameter to compensate for any flow loss. Both the intake and exhaust valves are Ferrea hollow-stem stainless units, measuring 2.125 and 1.625 inches, respectively.

Completing the flow system is an Edelbrock Performer RPM Air-Gap two-plane intake manifold topped with a Holley 830 HP carb. The manifold was deep port matched to the heads, while the intake plenum was modified by adding a 45-degree angle to one side of the divider. Henderson says, "The divider seemed to favor one side, so the angle was cut in to direct the flow." To make the carb adjustments easier and far quicker on the dyno, the metering blocks were fitted with Percy's Adjust-A-Jet system. These auxiliary metering blocks allow the main circuit metering to be adjusted with a simple turn of a screw rather than changing jets. On the exhaust side, a Stan's tri-Y header was selected to improve exhaust scavenging.