However, we wanted to make more without making any radical changes to the engine. In fact, we decided to make essentially zero changes to the engine and see if we could still make more power. Confused? Well, it gets better.

We did actually change one part, namely the cam. But we consider that actually not a change at all. You see, if you were building a motor from scratch and hadn’t already bought a cam, the “new” cam we installed would be the only cam to buy. Get it?

Oh, and one more thing. The new cam changed the engine’s firing order, too, and it’s what you might call the 4/7 swap. Racers have been doing this for quite some time. Swapping lobes 4 and 7 on the cam and distributor cap yields better power in most Chevrolet engines. Why is that, you ask? Here are the basics of the reasoning.

87-OCTANE ENGINE REVISITED

To make this kind of power, you need some cubic inches, so we started with a Dart Iron Eagle four-bolt block that had a standard 9.80-inch deck height. The bottom end carries an Eagle Specialties Pendulum Undercut 4340 forged crank. Eagle’s undercutting process strategically lightens the crankshaft, improving the engine’s ability to accelerate.

Connected to the crank are Eagle’s 5.850-inch H-beam rods floating JE pistons that were custom-made to take heavy abuse. Since we expected this engine to possibly detonate at some time in its lifespan (very hot days, long hauls and uphill driving, for example), we had Speed-O-Motive in West Covina, California, apply their specialized coatings to reduce friction on the piston skirts and reject heat from the piston tops (they also handled the block machining). A JE Pro Seal ring pack was selected because it’s designed to take abuse from heat and detonation.

The Airflow Research CNC heads have 180cc intake runners with extremely good cylinder filling capabilities and an awesome exhaust port. AFR’s standard 68cc chambers put the engine below 9:1 compression (8.77:1). Comp Cams 1.6:1 aluminum roller rockers are used in conjunction with the 2.02/1.60-inch valves.

CAM SPECIFICS

Since they greatly reduce friction, hydraulic-roller cams are the only way to go if you want to make great power with the least amount of heat buildup inside the engine. Lazer Cams ground a cam for this engine that works as well in a strong street car as it would in a high-performance truck or perhaps a racecar. It’s radical because of how much power it helps to produce without causing any noticeable detonation on 87-octane unleaded. It’s still mild because of the engine’s large displacement (409 ci) and because it could easily be driven every day. This cam, while considerably bigger than a stocker, will outrun many bigger cams in smaller motors, so it makes for a happy combination in this 400-inch-plus engine.

Other than the 4/7 lobe swap, the cam’s design is fairly straightforward. The guys at Lazer formulated that the lobe swap, especially when combined with a single-plane intake manifold, can improve cylinder filling over the stock firing order. Think of the engine as a big vacuum pump under the carb. Now, draw a picture in your head of the normal firing order at the intake manifold (1-8-4-3-6-5-7-2). After cylinder 1 draws in its mixture, the column of air/fuel in the intake manifold must switch directions and move to the back of the engine (8). Then for the next intake pulse in the old firing order, the column switches back up toward the front again (4), and then it moves directly across the engine to cylinder 3 and so on. With the 4/7 swap (1-8-7-3-6-5-4-2), note how after cylinder 8 draws its mixture, the column of air/fuel, which is already heading toward the back, now more easily slides across to cylinder 7. Then it gets a little better still after it moves up through the middle of the engine at cylinders 3, 6 and 5 and finishes at cylinders 4 and 2, which are right next to each other. It’s theorized that less momentum loss in the air/fuel column is why the 4/7 lobe swap adds power.