All six of the Cobra Daytona Coupes were equipped with (4) 48IDA Weber downdraft carburetors, as were all the competition 289 Cobras.
The Corvette Grand Sport engines were 377-inch aluminum smallblocks that ran (4) 58mm Weber sidedrafts on a crossram manifold.
Four Weber sidedrafts on a crossram manifold gave the '63 Grand Sport a faster revving engine with a hellacious midrange for coming out of the corners, making Weber carburetion systems ideal for these very special roadracing Corvettes.
All the factory competition Cobra roadsters of the mid '60's were equipped right from the factory with a hot 289 Ford V8 with a solid lifter cam and four Weber 48IDA carburetors. Nothing else looks better on one of these cars than eight stacks when the hood is open. On a Cobra, it has become what people expect to see.
Ford GT40 photographed at LeMans, 1967
A carburetor for race cars
Since the 60's, Webers have been considered "the ultimate carburetor". They were standard equipment on the finest racing and street machinery to come out of Europe (and America) throughout the 60's.The competition Cobras and GT40's were equipped with Webers, and they made enough power to lead Ford to a World Championship, beating Ferrari. That had never been done before. Those cars were all powered by Weber-carbureted Ford V8's.
Chevrolet V8's have "Weber roots" as well. The famous Grand Sport Corvettes were powered by special 377 cu. in. smallblocks with four Weber sidedrafts on a crossram manifold (today, I still build that same basic carburetion unit). The sidedrafts are the most exotic Webers of all, because they look so wild and different (photos below)...they are completely unlike any other carburetion system.
Today, Webers are the closest thing to mechanical fuel injection, but they're much better suited for the street. The engine performs and responds like it has fuel injection...except you're running carburetors. Many people call the Webers "injection", which is incorrect. It's not fuel injection, but your engine doesn't really know the difference.
Race cars have come a long way, and now use modern electronic fuel injection systems. Today, Cobra replicas and street rods account for the highest number of Weber carburetion systems still produced. Nothing matches the throaty carburetion "howl" of a Weber-carbureted engine when it's running floored, with the rpm's rising fast. It's music. And, of course, nothing is as impressive when you lift the hood.
Weber 48IDA (downdraft) and DCOE (sidedraft) carburetors, were recognized as the best racing carburetors in the world and were on virtually all of the fastest race cars of the 60's. There simply isn't a more efficient way to produce horsepower and torque throughout the entire rpm range with carburetors.
Even today, four Webers will still produce more torque over the whole rpm range than any other carburetion system. A modern four-barrel will usually match or beat them at redline, but getting to the redline fastest is what the Webers do best. They make race cars come out of the corners like rockets, developing super-strong midrange torque. They are specifically designed for independent runner manifolds where each throttle plate is dedicated to its own cylinder, with no central communication "plenum".
Thus, instead of making one big mass of air available to all 8 cylinders through a plenum, there are 8 individual columns of air that move very fast when the throttle is opened. That means constant high velocity with virtually perfect fuel distribution...and that's why Webers produce gobs of torque anywhere in the rpm range. It's all about air speed and fuel distribution.
From where you sit...in the driver's seat...the engine feels very "peaky" all the time; throttle response is instantaneous, and they make the car more fun to drive on the street. Regardless of the camshaft, the engine becomes more flexible and doesn't rely on high rpm's to bring on the torque.
When properly set up, Weber carbureted engines are a blast to drive on the street, where their flexibility can be appreciated. The hardest thing is to restrain yourself from constantly wanting to feel the power.