Lizzard Racing - 632ci Big-Block - The Big Picture Part 2

The struggle between what works on the street, and on the track, isn't such a struggle anymore, thanks to creative engine builders and the right parts. Such is the case with the 632ci big-blocks built by Lizzard Racing and its owner Matt Grillo. Using a Merlin II block and Dart's famed Big Chief cylinder heads, the big- block of your dreams is only a checkbook away.

The Big Chief heads are built on the GM DRCE pattern that you'd find on a Pro Stock race car. That's not to say that they can't work in the sportsman drag racing world or even on the street. The fact is that they're one of the best flowing heads on the market, especially when matched to bigger cubic inches than which they were originally designed. Where a Pro Stock engine would have a ton of closer to 16:1 compression and only 500 inches, this engine features a 13.8:1 compression (race gas required) and 632ci, so the cylinder head's large intake runners are better matched for low-end torque. This particular engine was built for the street-legal drag racing wars, and since it has a stellar combo of crankshaft and rods, you can add power down the road with nitrous, a blower, a hotter valvetrain or more compression.

Last month we looked at how the short-block came together, now let's get an in-depth look at how Lizzard prepares the heads, manifold, carburetor, and pulls it on the dyno.

Everybody has his or her own idea of just what "street driving" is. When Lizzard builds the street-driven version of its 632, Matt works very closely with his customer to identify exactly what this motor is expected to do. The basis is a 10.5:1 compression ratio, with a 1.1-1.2hp-per-cubic-inch formula, and the same high-end machining and quality materials used in Lizzard's competition engines. "Durability, reliability, and the feasibility of using pump gas are the absolute priorities," says Grillo. "Only then do the torque and horsepower numbers follow," based on the exact parts package agreed upon by Matt and the customer. This is the reverse psychology of building a racing engine--where high rpm horsepower numbers come first--and ensures that the sweet piece under that hood will actually get you where you want to go. Matt says that 50,000 miles can be expected, based on the amount of high-rev usage (over 6,000 rpm) the customer expects. Maintenance is a matter of regular valve-spring checks.

The biggest considerations separating the street-legal competition from the street-driven 632, lie in compression and valvetrain components. Pump gas, extended heat exposure, and varied rpm operating ranges, make preparing a monster motor intended to run at the track on the weekend, then cruise for 3,000 miles to that big summer event, a little more complicated than a motor you only hit for six seconds at a time. Matt typically uses a flat-top piston and a hydraulic-roller cam, which provide a very durable, streetable combination, which talks back to you with an average of 800 lb-ft of torque, and 650 hp. Other differences include a "driveability" tune on the King Demon, steel connecting rods, and, in most cases, a smaller cylinder head and manifold combination, as most customers don't have the room for a Big Chief setup under their hood. Matt's favorite alternate for the full-race head-intake combination is the Dart 360 head with Edelbrock's Super Victor manifold. This will often allow the motor to tuck in comfortably, and invite an air cleaner, power steering, and A/C to come in and party-down too. On top of all this is a bevy of options, including vacuum pumps and aluminum blocks. Oh, and let's not forget about the spray.