Automotive American – Classic Vintage & Modern
Tag: carburetor
Today our resident Stromberg expert Steve is going to show us his step by step process on rebuilding Stromberg 97s. This step by step process can also be used with Stromberg 48 & 81s but there are some differences between the 3 models. Please comment below with any tricks that we missed!!
Sources – Ken Layne @Motor.com and @RoadkillCustoms.com
Evaluating engine operation and pinpointing specific problems requires a comprehensive testing routine. Here’s how to do it.
There’s nothing more basic than the fact that an engine is just a big air pump. It draws in air by creating a low-pressure area in the intake manifold and cylinders, compresses the air, mixes in a little gasoline, lights a fire, generates heat and pressure and finally pumps out the spent exhaust. Our preoccupation today with things electronic sometimes makes us overlook old-fashioned mechanical symptoms of problems and the mechanical test equipment used to troubleshoot them. Vacuum gauges are often in this category, but the insight that a vacuum gauge can provide is as valuable today as it was 30, 40 or 50 years ago.
Remember that engine vacuum is just air pressure lower than atmospheric pressure. The starting point to evaluate engine vacuum is the intake manifold. When you connect a gauge to a tap on the intake, you’re measuring manifold vacuum. Note that vacuum will vary in different areas of the engine, such as above or below the throttle valve and right at the intake and exhaust ports.
Vacuum drawn from an opening ahead of the throttle is called ported vacuum. Throttle opening affects ported vacuum opposite to the way it affects manifold vacuum. For example, at closed throttle, manifold vacuum is at its peak. But there is no significant vacuum at a port ahead of the throttle plate when the throttle is closed. Vacuum appears at such a port only when the throttle opens.
It’s important to remember that manifold vacuum is used to power vehicle systems that need a steady supply of low-pressure air under all engine operating conditions. These systems include power brake boosters, a/c vacuum motors and some emissions controls.
Ported vacuum is used to control vehicle systems in relation to engine load. These include old-fashioned distributor vacuum advance diaphragms and carburetor assist devices. They also include many emissions control devices and transmission shift points. Under some engine load conditions, ported vacuum may equal manifold vacuum, but it can never exceed it.
Most vacuum gauges are graduated in inches of mercury (in.-Hg) and millimeters of mercury (mm-Hg). Some also show the modern metric scale of kilopascals (kPa). For comparison, 1 in.-Hg equals 25.4mm-Hg, or about 3.4 kPa. For this review, we’ll stick to in.-Hg, or simply inches of vacuum.
Because engine vacuum is based on comparison with atmospheric pressure, it varies with altitude just as atmospheric (barometric) pressure does. The following table shows that as altitude increases, vacuum decreases about 1 inch for every 1000 feet above sea level.
Sea level-1000 ft. 18-22
1000-2000 ft. 17-21
2000-3000 ft. 16-20
3000-4000 ft. 15-19
4000-5000 ft. 14-18
5000-6000 ft. 13-17
Normal manifold vacuum at idle for an engine in good condition is about 18 to 22 in.-Hg. Manufacturers used to publish vacuum specs in service manuals, but this isn’t as common as it was years ago. Still, the physics of internal combustion haven’t changed in a hundred years, so the guidelines given here are a good starting point for vacuum gauge troubleshooting. Your best analysis based on vacuum readings will come from your own experience, however. As you use a vacuum gauge on different engines, you’ll learn what’s typical for one model compared to another. Some engines have reputations as low-vacuum motors; others are unusually higher than average. Experience is your best teacher.
You can get a quick basic appraisal of engine condition by connecting a vacuum gauge to the manifold and a tachometer to the ignition to check vacuum and rpm at cranking speed. Warm up the engine first, then shut it down and connect your test equipment. Close the throttle and disable the ignition, or use a remote starter so the engine won’t start. Crank the engine for 10 to 15 seconds and observe the vacuum and tach readings.
Note that different engines produce different cranking vacuum readings. Some carmakers publish specifications; others don’t. Again, experience will be your best guide. What you’re looking for, most importantly, is steady vacuum and cranking speed.
If the cranking speed is steady (about 200 rpm) and vacuum also is steady (around 5 inches), the engine most likely is in good mechanical condition. If rpm and vacuum are uneven, the cylinders aren’t pumping equally. The engine probably has leakage past the valves, rings or head gasket. If the vacuum reading is pretty steady but cranking speed is not, you’re probably looking at a damaged flywheel ring gear or starter. If the cranking speed is normal or high but vacuum is low and slightly uneven, the engine probably has low compression or retarded valve timing. A jumped timing chain or belt is a common cause here.
The cranking vacuum test also can provide a quick test for PCV restrictions. Perform the test and note the average vacuum reading. Then pinch the hose to the PCV valve closed with your pliers and repeat the test. If the PCV system is clear, vacuum should increase. If it doesn’t, check the PCV system closer for restrictions.
You can zero in on several basic mechanical problems by taking a quick look at manifold vacuum. Warm the engine to normal temperature-get it really warm-and connect your vacuum gauge. Make sure you connect to a manifold vacuum tap and not to ported vacuum. Connecting a tachometer also is a good idea.
Just to be sure that the evaporative emissions system doesn’t interfere with vacuum testing, disconnect and plug the canister purge hose and its manifold port. If you’re testing an OBD II car, check for evap-related DTCs when you finish testing to be sure none set.
Run the engine at idle, low cruise (1800 to 2200 rpm) and high cruise (2500 to 3000 rpm). Note the vacuum readings, and any fluctuations, at each speed. Next, hold engine speed steady at about 2500 rpm for 15 seconds and read the gauge. Now release the throttle and watch the gauge as the speed drops. The vacuum reading should jump as the throttle closes, then drop back to its normal idle reading. If vacuum doesn’t increase at least a couple of inches when you release the throttle, you may be looking at worn rings, cylinders or valves.
Idle vacuum for most engines is about 18 to 22 in.-Hg, but some may produce only 15 to 17 inches at idle. (Remember what we said about experience.) If vacuum is steady and within these ranges, the engine and fuel and ignition systems are operating normally.
If vacuum is steady at idle but lower than normal, the ignition or valve timing may be retarded. Low compression, an intake leak or tight valves also can cause low vacuum at idle.
If the vacuum reading fluctuates within the normal range-the gauge needle bounces around a lot-uneven compression (broken rings or leaking valves or head gasket in one or two cylinders) is a likely culprit. An uneven air/fuel mix, erratic ignition timing, a misfire, misadjusted valves or a manifold leak near one or two cylinders also are possible causes.
If vacuum drops intermittently at idle, one or more valves may be sticking open or dragging. Higher-than-normal vacuum at idle is a common clue to overly advanced ignition timing, while low vacuum can indicate retarded timing.
Low vacuum also can be an immediate clue to a plugged exhaust. To check further, run the engine at about 2500 rpm for about 15 seconds. If vacuum drops during this period and does not increase when you close the throttle, you’re almost certainly looking at a restricted exhaust.
Several of the guidelines in this article have distinguished between steady vacuum gauge readings and fluctuating readings, where the gauge needle bounces up and down erratically. This may seem secondary-almost inconsequential-but it’s an important distinction. A steady but abnormal vacuum reading indicates a problem common to all cylinders. Things like incorrect ignition timing or an old, tired, high-mileage engine affect vacuum equally for all cylinders. A bouncing needle, however, usually indicates that the problem is localized to one or just a few cylinders. Here’s where power balance testing enters the picture.
Compression testing on many late-model engines is flatly impractical from a labor standpoint for a quick engine evaluation. That’s especially true on some of the weird vans for which removing and reinstalling spark plugs is a two-hour job. It’s relatively quick and easy, however, to connect a vacuum gauge to the manifold and your engine analyzer to the ignition system.
If your initial vacuum tests produce gauge fluctuations, you have a definite indication that the problem is limited to just one or a few cylinders. In these instances, a power balance test can help you pinpoint those cylinders and the condition they’re in. Does the engine need a valve job (fluctuating vacuum) or a complete engine exchange due to universally worn rings and cylinders (steadily low vacuum)? Combine modern power balance testing with traditional vacuum analysis and you’ll have the answer.
The author would like to thank the staff members of The DMV Clinic in Santa Cruz, California, for their help with this article.
If you know hot rods, you know Stromberg 97, right? Whether it’s the dry lake, the drags, circle track, car show, or just a street near you, they were the go-to, go-fast carburetor for generations. And you know what? They still are, if you’re building an early style hot rod or race car. Whether you’ve got a flathead four or eight, six-pot Chevy or Lincoln V-12, or pretty much any American OHV from ’49 to ’60-something, there’s an manifold somewhere to make it move a little faster, all with the tell-tale three-bolt, two-hole Stromberg carb mounts.
So where did it all start? Strombergs have been around since the earliest of automobile days. 1909, in fact, when Alfred Stromberg and five others formed the Stromberg Motor Car Devices Company producing one brass carburetor a day. By 1928, it was 4,000 a day thanks to some 12,000 staff. And in 1929, the company was sold to Bendix Aviation, moving to join their other operations in South Bend, Indiana. Up through the 40s to the 60s you’d find a Stromberg carb on your Buick, Olds, Plymouth, Stude, even Auburn and Lincoln. But by the 70’s the writing was on the wall for carburetion. In the USA, Stromberg’s last hurrah was the ’74 GMC V-6 truck. And in Europe they stuck the name on a Zenith-designed constant vacuum carburetor, flogged to a host of popular brands including Mercedes and Lotus.
But if we’re talking hot rods, it’s all about the 97. Easy to find. Easy to tune. Good for a reported 150 cfm through 15/16-inch venturis. Original equipment on Ford V-8s for barely more than two years—1936 and ’37. Yes, as we said, the carburetor of choice for hot rodders and drag racers right up to the 1960s.
So here’s the question: Why the 97? Chandler-Groves. Ford. Holley. Carter. Rochester. They were all around at the same time. A lot of them were bigger too, which offered more bang for your buck at the time. Its replacement, the Ford/Holley ‘94’ 2-bbl was Ford’s V-8 choice for some 15 years in various guises. And there were plenty of other Strombergs to choose from too. The 1933/34 Model 40 and 48 had a bigger 1-1/32-inch venturi and a reported 175 cfm. Some Lincolns had a 1 inch 160 cfm-rated LZ version, and Ford’s thrifty little V8-60 motor came with the 81, a smaller version of the 97 with a 0.81-inch throat, making it perfect in a 2×2 for your Ford 4-banger or V8-60 powered midget.
A gated neighborhood in an upscale Tampa suburb is a strange place to send your carburetors for rebuilding. The shop sits in the three-car garage of a lovely home, alongside a similarly lovely turquoise 1957 Chevrolet Nomad wagon. There is a long table with some chairs, and a workbench is parked next to a couple of soda blasters. All is lit by florescent bulbs overhead.
This the modest domain of Riley’s Rebuilds, a carburetor rebuilding service headed by Riley Schlick.
Riley is a 17-year-old girl: A surfing, skating, soccer-playing, Jeep-driving high school senior. Four of her high school friends, all girls, have learned to rebuild carburetors too, rounding out the staff of Riley’s Rebuilds. Ship them your worn-out carburetor, and they’ll ship it back soda-blasted, ultrasonic-cleaned and rebuilt to original specifications.
On what planet is this happening?
Here on Earth, actually, where a girl with a screwdriver, a drill, and some wrenches can earn “really good money,” Riley says. Her father, Dane, is an amateur mechanic. That’s his Nomad, which he’s had for about 15 years, and he also has a much-modified Dodge Little Red Wagon pickup that he drag races. He’s the one who taught Riley how to rebuild carbs, and she taught her friends, and now they all have part-time jobs “that pay us well,” Riley says. “For teenagers, anyway. So much better than minimum wage.”
Riley has always been interested in cars, starting out “holding the flashlight for my dad.” When she was 14, she told her parents, who are both in the medical field, that she wanted to buy a car that she could rebuild, getting it ready for when she was old enough to drive. Her parents said it needed to have a manual transmission, not go above 80 mph, and have a real roll bar. The logical answer was a manual-transmission, four-cylinder Jeep.
To buy it, she needed a job, and the only place that would hire a 14-year-old is a local grocery chain. No, her father said, we’re going to go out in the garage and figure out a way to make money. Hence the carburetor rebuilding operation, which has been in business for three years.
“I made the money to buy the Jeep in three or four months,” Riley says. They bought seats, wheels, tires, a new transmission, and had it painted in a “Jurassic Park” livery. She kept rebuilding carbs to pay for all that, and when it was done, she kind of eased off on Riley’s Rebuilds. But then she totaled out her friend’s Honda Civic, “and I had to pay for that—$10,000.” So it was carburetor game on again, and it hasn’t slowed. She’s saving money for college, even though she already has a scholarship offer to play soccer, which she does three or four nights a week.
Our hobby is full of contradictions; on one hand it’s steeped in tradition, on the other it embraces the latest technology. There are rodders, like Editor Brennan, who love the latest, high-tech components. Brennan’s gadget-oriented philosophy is “anything worth doing is worth making as complicated as possible”-if a computer, multiple sensors, and miles of wire is involved controlling any function he’s happy. Throw in a couple of blinking LEDs and he’s delirious. On the other end of the spectrum are those of us who consider simplicity the ultimate engineering accomplishment, no electronics, no wires, and the only mode is manual. Apparently there are more than a few who appreciate the uncomplicated approach. How else could the selection of brand-new old carburetors be explained?
Of all the carburetors that have ever been produced, two of the most popular have been the Stromberg 97 and the Holley 94. Today both are being reproduced-Stromberg Carburetors, a British company, offers the 97 and Edelbrock the 94; both are cosmetically identical to the originals with some unseen mechanical improvements. A third offering, the 9Super7 from Speedway Motors is similar in appearance to a Stromberg but will not be mistaken for one by those familiar with an original. Speedway has made several changes to the original design, including manufacturing the base assembly in aluminum rather than cast iron.
All carburetors have the same basic systems: an idle system to deliver fuel below the throttle plates when they are almost completely closed with the air/fuel ratio controlled by needle valves; a main system that delivers fuel to the venturi when the throttle plates open past idle; a transfer system that supplies fuel as the throttle plates open and the carburetor goes from idle system to main; a power system that provides a richer air/fuel ratio when the engine is under load; an accelerator pump to add fuel and prevent stumbling when the throttle is opened suddenly; a float, needle, and seat to control the fuel level in the bowl. Stromberg 97 and Holley 94 carburetors have these systems, but there are subtle differences in how they are configured. Let’s take a look at the two designs individually and then compare them.
Stromberg produced carburetors for a variety of automobile manufacturers but the versions that most hot rodders are familiar with first appeared as the Model 40 in 1934 on 85hp Ford Flatheads; the model 48 was introduced on V-8s in 1935 (the preceding were both rated at 170 cfm); and from 1936 to early 1938, 97s were installed on Fords (155 cfm). The smaller-model 81s (125 cfm) were used on the V-8/60s while the larger LZs (160 cfm) were found on the Lincoln V-12s. In addition to those factory-installed carburetors, what were known as Type I Stromberg 97s were manufactured by Bendix in South Bend, Indiana, as replacements for Holley 94s; most of these have the 97 logo. Replacement versions, designated the Type II, were manufactured by Bendix in Elmyra, New York, and have a 1-1 logo.
Holley 94s are often mistaken for Strombergs even though there are some obvious differences. Used as original equipment by Ford from 1938-57 and sold by parts stores as replacement carburetors 94s have always been more plentiful than 97 and as a result less expensive. Like many things that Henry Ford was involved in, the Holley 94 had an interesting beginning.
When Ford was getting ready to release the new 24-stud Flathead he contracted with the Chandler-Groves Company to develop an entirely new, more efficient carburetor and produce them for the 1938 production run. In exchange for that agreement, Ford was granted the patent on the new design and when the year was up he went looking for a better price on carburetors. Holley was able to cut the price by less than 10 cents a piece and became the sole supplier of 94s until production came to a halt in 1957.
As a result, carburetors produced for Ford in 1938 are labeled Chandler-Groves, those made by Holley may have the Ford script on the float bowl while some later-model versions have a 94 cast into the bowl. There are also replacement carburetors.
Now that new versions of both carburetors are available, the debate over which is better could go on indefinitely. The Holley 94 has two 15/16-inch venturi while those of the Stromberg 97 measure 31/32 inch. It would seem obvious that the slightly larger 97 should flow more, however their numbers are almost identical. Although Stromberg 97s and Holley 94s share the same three-bolt mounting pattern, there are a number of significant differences between the two. The fuel inlet is in the float bowl top of the 94s, rather than the side of the bowl as on the 97s. The 94s use a center-hung float as opposed to the side-hung design of the 97s. Finally, the 94s used spray bars for discharging fuel in the main system, while the 97s used emulsion tubes. All that being said, dyno testing has revealed that there is no significant difference between the two designs. The Stromberg is slightly better at producing horsepower in relation to the fuel consumed at low speeds (below 2,500 rpm) and the Holley is better above that range-but the difference is roughly 1 hp. So, why were 97s more popular than 94s on hot rods? One advantage of the 97 is that when multiple carburetors are used the main jets can often be changed without removing the carburetor from the manifold, not possible with 94s. Of course in a race environment that was important, on a street engine not so much. The other issue with 94s was the enrichment system.
Strombergs used a mechanically operated power valve that is only activated when the throttle was wide open and the engine can use the extra fuel. Holley’s enrichment system used a vacuum-operated power valve that opened to supply extra fuel to the engine when the vacuum dropped to a certain point, usually 7-1/2 inches Hg or less. The problem is that when two or more carburetors are used, the vacuum signal drops earlier and more aggressively than with a single carburetor. As a result, when using multiple carburetors the power valves may open prematurely, making the mixture much richer than necessary. This is easily cured by selecting a power valve that opens at a lower value. Another issue with using multiple 94s is their size. Slightly larger front-to-back than a 97, fitting three 94s on some manifolds can be a problem (a situation some responded to by grinding down the front screw boss on the float bowl).
Seems that the MyRideisMe.com Bonneville experience never runs out of steam. Hanging out at the Nugget one evening, we bumped into Clive from Stromberg Carburetors. After a lengthy BS session, the conversation turned to carb tech. And to cut a long story short, we asked him to contribute to our ongoing “5 Things” series. Alright, so 5 turned out to be 6 – or as the English say, ‘half a dozen’. Here’s what he had to say:
We’ve all seen those pics at Bonneville with 97 chokes removed and the kicker linkages brazed onto the base casting. It should make sense. No choke means more air space means more cfm. And you’d be quite correct, too.
Extensive 97 flow tests carried out this year by acknowledged race carb expert Norm Schenck showed that the carb did indeed pick up a little cfm without the choke plate installed. So all those Bonneville racers were right, after all? Well, yes and no. Salt Racers are only interested in WOT. On the street it’s a different matter.
Stromberg authority Jere Jobe told that 97s run better with the chokes in, so we suspected what Norm’s tests would show. Only we forgot to tell him the full story. Here’s what he said:
“I retested the signal curve with the choke butterfly and shaft removed, with somewhat disappointing results. The signal was unstable at most of the test CFM’s, and taking the average signal at each CFM to figure the signal curve showed a much less manageable curve than with the choke parts installed. My conclusion is that the choke butterfly serves as an airflow straightening “vane” that directs the airflow to the area of the boosters with reduced turbulence. Even though the choke parts cause a reduction in flow, it is not a good trade to lose good fuel metering for that CFM gain.”
So there you have it. The same story from two very qualified horse’s mouths.
By the way, if you want to keep your choke plates fixed open, try our Choke Lock Detent kit (Stromberg Part 9537K-L), which replaces the usual round-tipped detent pin in the airhorn to lock the choke plate open.
Stromberg main jets are easy. What you see is what you get. Stock Genuine 97s come with 45s which means 0.045inch. Power by-pass valves (PV) – the ones underneath the accelerator pump — use the old engineering Number and Letter Drill system, devised as a way to fill in the gaps between the 1/64th sizes. And to complicate matters, the bigger the number, the smaller the drill!
And to complicate things even further, changing your PV by one number does not always mean the same change in jet size! We offer everything from #72 up to #60 (note that I said ‘up to’). The #72 is 0.025inch, #71 is 0.026, but #70 is 0.028 (a two thou’ jump), then #69 is 0.292 (WTF!) . The gap between #66 (0.033) and #65 is also 0.002inch before it returns to 1 thou’ per size right up to #57. We didn’t make the rules! But it pays to remember this when you’re trying to rejet.
And while we’re on the subject, remember that the PV only starts to affect the fuel ratio at just after 50% throttle. And when you swap them, cut a slot in the centre of a wide blade screwdriver so you don’t
The float in a Stromberg 97 (and 48, 81, etc.) is supposed to be set so the fuel level (not the float itself) is 15/32 inch (plus or minus 1/32) below the top edge of the casting without a gasket. But to be honest, that’s easier said than done, especially with the engine running and a cigarette on the go.
So for increased customer safety, our Premium Service Kits (9590K-97 and 9590k-81) now recommend that the float is set ‘dry’, as we do at the factory. Rather than a float gauge, our kits now include an extra leaflet about setting the float level. To download a copy, click here. Basically, just get the float so it sits level in the bowl when the inlet valve is shut.
All new Genuine 97 floats are pre-set at the factory, but if you’re rebuilding, you adjust the front ‘tang’ of the hinge to push it nearer or further from the inlet valve. If (and only if !) the carb is empty of gas, hold the bowl section upside down so it closes the valve by its own weight, then eyeball it through.
Some time ago before my Dad passed away we had chatted about what upgrades might have been done to the coupe back in his days. He was born in 1936. Before I managed to get the parts my Dad sadly passed away.
So as a bit of a tribute I bought the following parts
Stromberg 97 Carb – from Dave O’Neil (O’Neill Vintage Ford)
Scalded Dog Manifold – from Charlie Yapp (Secrets of Speed)
Chrome Air Scoop – from Dave O’Neil (O’Neill Vintage Ford)
Facet Electric Fuel Pump – Carbuilder.com
Petrol King Fuel Pressure Regulator – Carbuilder.com
Fuel Pressure Gauge – Carbuilder.com
Braided Fuel Line – Carbuilder.com
Copper Fuel Line – Amazon
Rubber Fuel Pipe – Carbuilder.com
Various Connections and Unions
Jubilee Clips -Screwfix
Fuel Pump Relay – eBay
Rocker Switch – eBay
Parts I already had
MSD plug lead set and tool
Modern distributor cap
Wire and connectors
My friend Austen fabricated the required new throttle link rod from the dimensions provided by Charlie
First job is to remove the existing manifold and carburetor
This is a Model B carburetor fitted by a previous owner, this carb has had a brazed repair in the body which whilst a bit rough and ready worked fine.
These inlet manifold fixing bolt holes where not used with the original manifold, but are needed for the new one. These were cleaned out with a tap.
The carburetor and manifold were assembled and bolted into place
First attempt at wiring the fuel pump and the use of braided fuel line. This looked quite bad as the wiring was temporary to get home from my friends workshop. I didn’t like the look of the braided line.
Decided to go with copper fuel line with rubber termination to solve any issues with engine movement that may cause leaks.
The fuel pump and regulator fit nicely in the chassis rail, these were removed to change 90 degree elbows for a better pipe run
First attempt with copper/rubber fuel pipe as you can see the wiring is a lot tidier, you can also see the pipe run between the pump and the regulator. The wiring will be tidied and weatherproofed further. Use of the screwed connector has been chosen to make a pump change on the road easier.
This is a view from above, quite tidy but still not happy! Too much pipe run above the exhaust manifold and the carb feed pipe is not secured enough for my liking.
At this point a leak from the sediment trap was noticed, caused by the failure of the gasket
The reproduction item is made of neoprene but a horrible fit and had to be cut to fit. Bowl and trap were cleaned and then reassembled
Wasn’t happy with the throttle feel so spaced with some fibre washers, a lot better now. The throttle also stuck a little, so the joints on the rods were lubricated and Clive at Stromberg provided a nifty little solution to snap the throttle shut. This also doubled as a safety measure as per Charlie’s advice in case of linkage failure.
As you can see runs very well, starts better, warms up quicker, very happy.
More once I get a few trips under my belt with the new set up.
Big Improvements for the Little Banger
When Ford introduced the Model A in late 1927, it was remarkably different from other automobiles offered at the time, even Ford’s own Model T. In many ways, it was a clean sheet design when compared to Ford’s previous line. Many similarities abound, but the Model T and the Model A differ in more ways than they are similar. And four years later, when the Model B came along, the story was very similar. If the brass at Ford at the time were learning things as they went, it was pretty obvious that they were incorporating those things in real time. So, it should come as no surprise that as the new models came out, hot rodders borrowed parts for their older Fords. Wheels, brakes, shocks, transmissions, engines, even complete frames were common swaps for the earlier T and A models as better components were introduced on Ford’s latest offerings.
One of the early hop up techniques for the Model A was to swap to the larger 1932 Model B Zenith carburetor. Equipped with a similar, slighlty upgraded flathead four-cylinder engine, the Model B Ford was fed by a slightly larger updraft carburetor (1 1/8-inch) than that found on the Model A (1-inch). While that small difference in size may not sound substantial, it actually equates to a 26% increase in area which translates into more air and fuel that can be fed into the A engine. That small increase can yield upwards of 4 horsepower. Another inconsequential sounding number, but when added to the A’s paltry 40 horsepower, results in a net gain of 10%. Not too shabby for the 1930s!
One V8 hot-rodding trick of the ’50s that never quite caught on was the 5×2 carburetor setup. But you know, it’s not such a terrible idea.
The photos we’re sharing here have made a few laps around the hot-rodding message boards across the internet, where they never fail to stimulate interest and discussion. The images depict an idea that originated in the early-to-mid-50s for souping up American V8s: the 5×2 carburetor setup, with an intake manifold specially cast (or modified from a production component) to accept five two-barrel carburetors. While the configuration never really caught on, it’s not as strange as it may look today.
The system above, apparently built up from a production Pontiac V8 intake manifold, uses five Rochester 2GC two-barrel carburetors laid out in an X pattern, with the center carb in the original stock location. The early Oldsmobile (1949-64) manifold in the lead photo is of similar configuration, and also includes Rochester-style carburetor mounting flanges.
This Winfield intake, Cyclone adapter (to install a Stromberg), and RayDay cylinder head were removed from a Model A in 1956. Images courtesy Evan Bailly and as noted.
We are suckers for vintage speed equipment. The hobby of making inexpensive cars faster goes way back—it predates the term “hot rod” by decades. While some names have been around for ages and are so well-established that they’ve become background noise, there are far more companies that tried to enter the business of hop-up parts and didn’t make it. Some folded their tents entirely, but others had come from the more-general auto-supply business and returned to that.
Read David’s excellent article here
