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Speedway Motors 9Super7 - Tri-Power In Under An Hour - TechWe Test And Tune Speedway Motor's New 9Super7 From the February, 2011 issue of Custom Classic Trucks By Ryan Manson
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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. Setting up the carbs proved easier than I thought and just as Speedway advertises. Once we got the primary carb adjusted to provide sufficient idle to keep the engine running, it was a simple dance between the secondary carbs with the Uni-Syn and a screwdriver to adjust their idle settings. Back and forth between the three carbs got them all in sync while keeping the idle at a reasonable rpm (we had it down below 800 rpm and it ran like a clock). About 20 minutes after bolting the carbs down, we had them tuned and were running up and down the local "strip" smiling with glee every time those secondary carbs came on, bringing with them a sudden rush of acceleration and that "whoosh" of air as six barrels of carbureted fury suck air and fuel into the engine. The thought of a bolt-on carburetor ready-to-run out of the box based on a 70-year-old design just doesn't seem possible, but it did, and I did it. And if I can do it, Speedway must've made a REALLY nice product, because I can't usually tune a radio let alone a carburetor. So if you're engine compartment is in need of a vintage vibe, check out the Speedway catalog or go online at www.speedwaymotors.com. Making Hard Lines Easy
I wasn't real happy with the rubber fuel hose setup and decided to take the time to make a few hard lines and clean up the tri-power install. I found a handful of Ford compression fittings to install at the carb inlets from Mac's Antique Auto parts and proceeded to scour the hardware store for the rest. I also decided to get rid of the bulky fuel block with a sleaker 3-in-1 fuel line made from 1/4-inch stainless steel. It was a little tricky welding the three lines together, but with a little patience, I was able to pull it off. The end result is much cleaner and a bit more professional than it was before with all those black hoses.  Here's the regulator with...  Here's the regulator with the pressure gauge on the left side installed, along with the stainless compression tube fittings on the inlet and outlet side-more on these a little later. A small fuel filter will be used just before the fuel pump to ensure no debris gets inside.  With the Edelbrock intake...  With the Edelbrock intake bolted to the engine and torqued to spec, we installed each carb with the mixture screws (the two small guys on the front of each base) a turn and a half out. This is a pretty good baseline setting that we'll dial in later. Each carb was then plumbed to the Edelbrock 3x2 fuel block. Note the absence of any linkage, save for what existed coming from the pedal.  The first step is to get the...  The first step is to get the engine to fire and idle at a decent rpm. After ensuring that the two end or secondary carb idle-speed screws were backed out sufficiently, we turned in the idle screw on the primary carb to help bring the engine to idle. Once fired, the idle-speed screw is further finessed until the engine hovers around 800 rpm.  The next step is to sync the...  The next step is to sync the carbs. This ensures that all three are pulling the same amount of vacuum at idle. A Uni-Syn Carb Sync tool is placed over the throat of the primary carb and is adjusted until the ball floats in the center of the gauge.  Here's the "secondary" or...  Here's the "secondary" or progressive portion of the Eelco linkage kit. This mates the two secondary carbs together and regulates when they open.  With all three carbs synced,...  With all three carbs synced, the secondary linkage can now be installed on the throttle shafts of the secondary carbs. Care must be taken to ensure that the linkage is attached without moving the throttle shafts off their "idle" settings, thereby changing the tuning that was just set.  Next, the secondary carbs...  Next, the secondary carbs are checked using the syncing tool. Both carbs required adjustment on the idle-speed screw, which bumped the idle rpm of the engine up slightly. By going back and forth between the primary carb and secondary units, small adjustments were made until all three carbs measured the same vacuum via the Uni-Syn gauge (synced) and the engine idled at a proper rpm rating. At this time, the primary linkage between the throttle pedal and primary carb can be attached.  It takes a bit of trial and...  It takes a bit of trial and error to set when the secondary carbs kick in, we adjusted ours to come on just before the primary carb reaches half-throttle. A bit of driving will tell us if that's where we like it. The easiest way to determine this is to set it to when the four-bbl carb's secondaries come on, but it really comes down to personal preference.  It's a bit cluttered due to...  It's a bit cluttered due to the placement of the fuel block on the driver side of the intake with the linkage behind but it allowed for the easiest routing of the fuel line from the stock mechanical fuel pump. We'll come back to this in a minute.  With the fuel lines removed,...  With the fuel lines removed, you can get a better idea of what the installed linkage setup looks like. Note that all three carb arms are clocked at the same ten o'clock setting. It's very important that they're parallel and cannot be opened over center, causing a potential stuck wide-open throttle situation. We bent a piece of tubing to clear the linkage and fuel lines, which attaches the throttle pedal linkage to the primary carb arm with a pair of heim ends.  This compression fitting is...  This compression fitting is unique to Stromberg carburetors and enables 1/4-inch hard line to be used without flaring the tubing by using a ferrule to hold the line in place.  The passenger side, however,...  The passenger side, however, is much cleaner, with only the choke linkage, idle-screw assembly, and accelerator pump linkage visible on the three carbs. We topped off the trio of carbs with Tru-Helmet air cleaners to give the setup a classic, hot rod vibe.  This compression fitting is...  This compression fitting is unique to Stromberg carburetors and enables 1/4-inch hard line to be used without flaring the tubing by using a ferrule to hold the line in place.  Another style compression...  Another style compression fitting is the stainless steel one shown here. This will be at the opposite end of our fuel line, at the regulator. The compression end is 1/4-inch while the pipe fitting is 3/8-npt. Note the relation of the ferrule to the fitting.  A small ratcheting tubing...  A small ratcheting tubing cutter makes quick work of cutting the tubing to length. Here, 5/16-inch tubing is cut to run from the fuel pump up to the regulator.  Once cut, a deburring tool...  Once cut, a deburring tool is used to clean up the edge and remove any debris.  We'll start at the back carb...  We'll start at the back carb and work our way forward since this will basically be one piece from the regulator to the rearmost carb. Notice that I gave the linkage a wide berth so as not to interfere.  A little measuring, a few...  A little measuring, a few bends, and a lot of mock up later, and we've got our first line.  Since I want all three lines...  Since I want all three lines to be nice and parallel, it's necessary to make them all the same length. I first bent a 90-degree radius in one end and then I marked the length for the next perpendicular bend to begin.  A few minutes later and I...  A few minutes later and I have three lines mocked up. At this point you can see where this is going.  The vertical lines are slightly...  The vertical lines are slightly long, but for a good reason. They will effectively be cut in half so as to flow into the main line with a nice, smooth radius.  To make the opening in the...  To make the opening in the main line, I simply used a die grinder to remove the material after I marked each spot in relation to the vertical lines.  A little work with a file...  A little work with a file and I had two nice, clean openings.  This photo illustrates what...  This photo illustrates what I was explaining earlier about the vertical lines being slightly long. Notice the smooth transition between the main line and the vertical lines.  With everything trimmed to...  With everything trimmed to fit, it was time to start tacking the pieces together. Obviously, this would be much easier on the bench, but that would require removing the intake from the motor. Instead, I simply tack each joint with the line installed on the engine...  ...and finished welding it...  ...and finished welding it on the bench. I made each vertical line as long as possible from the main line so as to reduce the likelihood of anything binding and to allow each line to flex.  Here's the finished line welded...  Here's the finished line welded up.  And here's the line installed...  And here's the line installed on the engine.
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The Thinker??? - Haul Monitor
Ryan talks about the friendly badgering that goes on around the shop and overcoming obstacles that seemly pop up out of nowhere during a project....
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