Interesting Weber jetting

[What'saCobra?]

My commendation on your patience and success. It is true that when set up correct, NOTHING is better "feeling" than the Webers compared to any Holly (though i have absolutely NO experience with their fuel injection units.)

When i moved from Weber-equipped Cobras to Weber-equipped FA/5000 (all Chevys), the crispness of a proper set-up was similar. However, it must be said that a poor Weber tune is also one of the most awful experiences, nearly always rich or very lean in a few spots (ergo the common spitting back through the intake, while stinking of excess fuel). You have to admire the Italian style and patience with making Ferraris run correctly and with fairly reasonable fuel economy. Though, mind you, their engines are generally very small displacement per cylinder and the smaller venturi systems seemed to be better metering in the day then our carbs(that is, maintaining correct fuel/air ratios with better precision when warm. Even the street cars, however, were cold-blooded beasties, needing warm manifolds and warm gear-boxes to run correctly. But, when warm, they were simply fine to drive and hear.

The only better system i have ever driven has been the Lucas/Kinsler mechanical injector systems that were common on the large Can-Am cars. Jim Kinsler, Bless his soul, knows how to design, assemble and tune those systems to a fare-thee-well, just about perfect.

The Lucas system uses a shuttle-cock moving back and forth over a changing-length tube to vary the amount of each fuel charge rather precisely. Injecting the fuel from the top of the big intake tubes (often referred to as Calliope tubes) allows the air-fuel mixture to be quite homogenized by the time it gets to the intake port. Once the manifold is warm very little fuel "wetting" occurs, with little corner edges to pass via a long straight shot. With such large openings and long lengths very little drag exists, while plenty of mass-momentum is available.

The Lucas absolute free-flow rate available is far over 4000 cfm, but of course is far in excess of even the biggest road-race Chevy. But, with the precision charge of the mechanical shuttle-cock, completely the opposite of the older constant-dribble Hilborn systems, the engine tolerates wide-open-throttle demands even at medium rpms with ease.

The net result is a wonderful flat torque curve AND a very high peak power, all the way from 2500 to over 7500 rpms. For road racing, this is ideal. If you miss a shift and skip a notch on the way up (not an unknown error?), the engine will still pull like a freight train and very little time will be lost.

The only drawback is the very tall pipe configuration, not welcome under any hood, but ideal for mid-engine layouts. You have to admit, having those huge pipes sticking up in the back is very appealing eye-candy, no? (See red car picture in file)

Oh yes, another drawback is a current new system is around 20K USD. Plus, depending.

Again, my compliments for your set-up.

PS: Lately, i have been thinking that one of the newest Holly Dominator systems with a tall hand-fabricated intake manifold, might be able to replace the old Lucas, but would have to test it properly, far beyond my current retirement planning. Lots cheaper, though and far better metering (accuracy in F/A ratio) than in the past. Holly has done a lot on this and i would love to try one.