Introducing the new and Improved 9Super7!
The Stromberg 97 and its siblings, the larger 48 and more diminutive 81, are arguably one of the most popular lines of carburetors among hot rodders ever produced. While the Carter AFB, Edelbrock, and Holley four-barrels have definitely taken some of the wind out of the Stromberg's sails over the years, the faithful have stuck to the old two-barrel jug for everything from stock Flatheads, their original motor of intent, to fire-breathing, Nitro-drinking, tire-smoking dragsters. Getting more fuel and air into the engine was the name of the game and guys have been using the old carbs for just that since the late '40s. Since then, they've been used to emulate the setups ran in the early days of hot rodding but their rise in popularity has likewise caused the demand, and have therefore caused the price, to rise as well. And with the availability of decent, rebuildable cores steadily on the decline over the past ten or so years, it's getting harder and harder to build a reliable multiple carburetor setup until now.
Speedy Bill Smith and his crew at Speedway Motors, in Lincoln, Nebraska have been catering to the hot rod and racing market for over the past half century, providing parts and service unequaled in the aftermarket world. From suspension parts to rolling roadster kits, to say that they've kept the proverbial hot-rod torch burning all these years would be an understatement. They've managed to keep their finger on the pulse of hot rodding all these years, so it should come as no surprise that they saw the writing on the wall when it came to the dwindling Stromberg resource.
That's when they decided to step in and do something about it by introducing a 100 percent completely new carburetor based on the legendary Stromberg 97. Dubbed the 9Super7, the old 97 has been reproduced to the closest legal allowances and is everything the original Stromberg 97 is, was, and then some.
Aesthetically, the 9Super7 is nearly identical to the stock unit, minus the large 97 logo that graced the side of some of the older jugs and the patent numbers commonly found on the float bowl area. They've also upgraded some of the internal bits, notably the float, needle, and seat. Jetting and power valve settings remain as they were for the original 97 carbs as well as the cfm and vacuum specs.
The other similarity that the 9Super7 shares with its antique counterpart is the setup and tuning necessary to yield a well-running machine. While perhaps not as simple as bolting on a single four-barrel, the 9Super7 makes setting up a multiple-carburetor induction system easier than when Strombergs were available new. All that's required is an intake, a linkage system, a Uni-Syn syncing tool, and a little patience.
We scored a decent small-block Chevy recently and figured it would make a perfect engine for the setup. Equipped with an Edelbrock Victor Jr. intake manifold topped by a 750-cfm Edelbrock carb, the little 327ci engine lacked both low-end torque as well as curb appeal when it came to the engine compartment. And with fuel prices being what they are, the thought of cruising around on a single two-barrel with a pair of secondary carbs at the ready when warranted, a tri-power setup was just too hard to resist.
We started out with a trio of Speedway's 9Super7 carbs, all set up with their idle circuits intact, before contacting Edelbrock for a 3x2 intake and fuel block. A progressive linkage kit was also picked up, provided by Eelco, that will allow the carbs to be set up to open progressively, with the center carb operating as the primary and the outer two operating later as secondary carbs.
Here's the new carb, fresh...
Here's the new carb, fresh outta the box. Speedway ships them only after a flow test and leak inspection has been done to ensure trouble-free installation. The choke assembly, accelerator pump, and jets have all been faithfully retained and accept standard Stromberg parts.
Here's a bird's-eye view of...
Here's a bird's-eye view of the float bowl and venturis. Speedway kept to the original Stromberg specs of a 0.97-inch venturi diameter but upgraded the float to a neoprene unit.
The biggest upgrade, however,...
The biggest upgrade, however, was made to the troublesome needle and seat inlet, replaced by a Grose Jet inlet valve. This valve better copes with higher fuel pressures and improves high-speed running and won't stick or dribble like the old viton-tipped needle and seat setups. The Grose Jet valve also won't corrode in modern fuel, something the original needle and seat units could be known to do.
The 9Super7 carbs are shipped...
The 9Super7 carbs are shipped with a #65 power valve, identical to the stock 97...
...as are the 0.045-inch main...
...as are the 0.045-inch main jets.
Here's a neat cutaway from...
Here's a neat cutaway from a display carb showing the details of the main jet location on the bottom of the float bowl.
Changing jets is still tricky...
Changing jets is still tricky with the carburetor installed on the intake manifold, especially in a multiple carb setup.
One important aspect of setting...
One important aspect of setting up any Stromberg system is to have the proper fuel pressure. We wanted to retain the reliability of a mechanical fuel pump, so we opted with a lower pressure unit from Summit Racing combined with a fuel pressure regulator adjustable from 1 to 4 pounds, perfect for the Stromberg's 31/2-pound liking.