Brul rattled the walls to the tune of 515 hp and 552 lb-ft of torque with an 850-cfm Edelbrock Performer RPM Q-Jet we had on the shelf. Because Q-Jets work so well off-road, we thought it deserved a shot. Our air/fuel ratios for the dyno pull hovered right around 10.9:1-11.3:1, indicating a rich condition. Brul could've monkeyed with swapping metering rods to lean it out, but Q-Jets are pretty complicated to work on, and dyno time is dyno money.
Instead, we went for the jugular and bolted on an 850-cfm Barry Grant Race Demon. The Race Demon is a full-on performance carb that doesn't mess around with choke horns and pedestrian niceties. It offers features like billet aluminum metering blocks, removable boosters, high flow, concentric venturis, a billet base plate, and a host of other features. Barry Grant automatically recommends the Race Demon for any engine with a cam as large as ours, but Brul suggested we could've gone with the company's Mighty Demon carb to save a bunch of coin with little to no loss in performance because our power levels weren't exactly in the stratosphere.
We were shocked to see the power rocket to 533 hp and 563 lb-ft of torque with an air/fuel ratio right on the money at 13.1:1 with the Race Demon bolted on as delivered. Brul then advanced the timing from 32 degrees to 34 degrees BTDC, and we were rewarded with 541 hp and 569 lb-ft of torque. That's and extra 26 hp and 16 lb-ft with just a carb swap! Even though both carbs theoretically delivered 850 cfm, the difference in the Demon's more efficient fuel atomization and superior metering system really delivered the goods. Aside from adjusting the idle air screws, we did no other tuning to the carb.
To make life simple, we called Performance Distributors and sent in our engine and camshaft specs. The company sent us a DUI HEI distributor and a set of Livewires. The mechanical advance curve was so right that we didn't have to crack the cap. Because we didn't need to worry about the ignition timing, we turned our attention to setting the valve lash.
On a hydraulic camshaft, there's a plunger inside the lifter that takes up the lash, or slack in the valvetrain as the pushrod interacts between the rocker arm and lifter. On a mechanical camshaft, you've got to set the valve lash yourself. Once the engine was broken in and warmed up, Westech set our valve lash to Comp's specified 0.020 inches. Some guys may fudge the valve lash a little to affect the camshaft characteristics. Loosening the lash will make the cam act bigger, while tightening the lash will make it act smaller, but the results can be poor idle quality and noise if the valves are too loose, or bent or broken parts if they're too tight. It's always better to go with the manufacturer's specs.
Mondello employed several tricks like installing its Posiflow swirl polished and backcut valves and CNC-preparing the Edelbrock heads and performing its Mondello blueprinting to the Torker manifold. The CNC mods add 35 cfm capacity to the heads, bringing the flow numbers up from roughly 278 cfm intake and 179 cfm exhaust at 0.500-inch valve lift to 313 cfm intake and 214 cfm. The good flow numbers combine with the ports' shape and the manifold mods to maintain a high port velocity and a tunnel ram effect.
We then swapped on the Victor manifold and made another pull with all the parameters as before. After checking everything to make sure we hadn't missed a step and advancing and retarding the timing, we were surprised to muster a best of only 532 hp and 552 lb-ft of torque. To see why we were 9 hp and 17 lb-ft off our best numbers with the Torker, Brul installed an air meter hat over the carb to check airflow with the Victor and made another pull. We then put the Torker back on and recouped our lost power.
The air meter showed the Victor and Torker were moving the same amount of air, but the larger ports and longer runners of the Victor resulted in slower air velocity. The air just plain got lazy with the Victor. For an engine of our size, trading velocity for volume just didn't cut it, so the Torker stayed on for the rest of our testing.