THE BIG-BLOCK FROM HELL cont’d

—courtesy Sport Truck magazine; Photography: Mike Finnegan

After installing the beltdrive, Dave degree’d in the camshaft to LSM’s specifications using this Moroso wheel. He installed the camshaft 2 degrees advanced as a baseline defore dyno-testing.

Next, a TCI Rattler crankshaft torsional vibration absorber was pressed onto the snout. This SFI-approved part features timing marks etched into the surface that won’t ever disappear and a design that absorbs the amplitudes of crankshaft vibrations rather than damping them. According to TCI, this translates into a smoother running engine and improved valvetrain stability.

Since we aren’t installing a distributor into the intake manifold, we opted for Jesel’s front mount distributor. The distributor is a low-profile unit that is driven from the front of the cam drive via a small belt. The benefits of this part are many. Plug wire routing is cleaner, and we gain clearance at the firewall, but perhaps most importantly, we negate any ignition timing issues that may come as a result of the camshaft deflecting at high rpm, which we’d encounter with a conventional distributor mounted at the rear of the engine.

MSD’s crank trigger system will prompt the ignition coil to fire in a precise manner, thanks to strategically placed magnets in the trigger wheel.

Because we chose low-tension piston rings, we needed a vacuum pump to improve ring seal in the cylinder. Dave made a custom mount for Moroso’s three-vane pump, which is driven by a V-belt and 4-inch crank pulley. The pump draws through the valve cover and exhausts into a Moroso tank mounted off the front motor plate. The pump pulled 15 inches of vacuum during dyno testing and didn’t require a pressure release valve.

To power the ignition system, we installed an MSD 6AL box, HVC coil, and 8.5 mm Super Conductor wires. The AN fittings at the corners of the manifold are from Earl’s and connect the water jackets from the front to the rear of the block to prevent steam pockets from forming while the engine is running.

After assembly at DNE Motorsports Development, the engine was taken to Westech Performance Group for dyno testing and tuning. The engine was tested using several different types of headers. Water temperature circulating through the engine was regulated at 180 degrees F or less. The engine consumed nothing but 91 octane gasoline that you’d find at your local fuel station.

During the session, Dave made carb adjustments and jetting changes to strike a balance between maximum power and driveability, but otherwise the carb worked well right out of the box.

An Innovate wide-band O₂ system was used to monitor air / fuel ratio in all eight cylinders, and Dave also checked the spark plugs to judge the running condition of the engine.

After making several short pulls to gather baseline data and to ensure that there were no mechanical problems, we drained the dino oil from the crankcase and re-filled it with Royal Purple 5w30 full synthetic oil. We immediately noticed a 13 hp increase in peak power during the follow-up pull.

THE FINAL WORD

engine photo This engine made 1,008 hp at 7,000 rpm and 814 lb-ft of torque at 5,900 rpm during its first full pull on the dyno. The fuel curve looked fairly smooth, but Dave felt there was more power sitting on the table with fuel and timing adjustments. We spent the next 5 hours testing different header designs, various cam and ignition timing maps, and carb jetting changes during more than 30 pulls on the dyno. The motor never dropped below the power level of the first pull. In the end, we discovered this motor liked 29 degrees of timing advance, 2.5 degrees of advance for the camshaft, and 90 / 97 jetting. It also ran best with 2-1/4-inch primary tube/4-inch collector headers. Advance or retard the ignition timing or cam timing from there, and the power falls off. Allowing the engine to run to 7,300 rpm showed that the power began to fall off just after 7,200 rpm, with a peak of 1,060 hp. The torque peaked at 5,900 rpm with 827.5 lb-ft.