John Marcella, owner of Marcella Manifolds, builds custom aluminum intake manifolds. He does some modification work and builds manifolds for oval track racers, but his bread and butter is drag racing. His business took off after posting photos of his handiwork to an industry web forum. His craftsmanship and reputation have kept him busy, building each manifold from scratch to meet each customer’s requirements.
“Every manifold job I do is a completely custom, one-of-a-kind piece for the customer’s application,” says Marcella. “I’ve never built two manifolds alike because every engine combustion requires something completely different. Whether it be the runner length, taper, plenum size, packaging issues within the car itself — I’ve never met two of the same manifolds.”
The intake manifold is a critical part of any racer’s engine, as its design heavily affects engine horsepower, torque and performance. Aluminum weighs less and transfers heat considerably better than other materials, which makes it ideal for these high-performance applications. However, aluminum provides a number of welding challenges, including warping and varied bead appearance due to heat input and arc characteristics. In this article, we’ll look at how Marcella addresses these issues with TIG inverter technology, such as the Dynasty® 350 AC/DC TIG welding inverter from Miller Electric Mfg. Co.
Passion for Racing, Quality Drives Marcella
John Marcella keeps his own race car in the back of the shop and uses it as a test chamber in his continuous quest for extra horsepower.
“I love the sport, the problem is I’m not a very good racer,” he says. “But I do it for fun and I use my own car as a test bed for new ideas because you can’t just try something on a new customer. It’s got to be proven theory before I can put it out and give it to a customer.”
Marcella showed an aptitude for welding in high school and credits a teacher of his — Paul Bose at Utica High in Shelby Township, Michigan — for setting him on his current career path. After competing in VICA (now SkillsUSA) and excelling in the automotive trade as a cylinder head developer in Detroit, Marcella struck out on his own to form Marcella Manifolds. He now works out of his own shop and ships manifolds around the globe.
“Most manifolds take about a week-and-a-half to construct from the start of the design to the finished product,” says Marcella. “Some of it is more involved dealing with twin turbocharged applications where two injectors per cylinder are required, or multiple power adders are being used, so there’s more fabrication to be done. Those applications take approximately two weeks.”
“Most of the material that I use is 6061 aluminum—primarily bar stock—in ranges of 3/8 inch up to 1/2 inch. All the flanges are 1/2-inch thick, and the runners of the intake valves are always 3003 aluminum. Filler rod is typically 4043.”
Marcella has two priorities when welding aluminum: minimize heat input and control coloring/aesthetics. Aesthetics, particularly, play a role in his material choices.
“I’m big on the color of the material I use,” he explains. “(3003) seems to have a nicer weldability to me. It yields a brighter color within the weld itself, and that’s important to me. I want my stuff to look nice.”
Marcella’s newest welding system features the Dynasty 350 and a complete TIGRunner® package from Miller with a welding cart and self-contained Coolmate™ cooling system. The system is further optimized with a wireless remote TIG foot control that offers precise operator control without the clutter and hassle of corded models.
“The first TIG equipment that I used versus what’s available today is just light year’s apart,” says Marcella. “The inverter machines have changed everything as far as AC welding is concerned. For somebody who’s trying to do nice work, it’s everything because the controllability and stability of the arc is just incredible.”
Eliminating Soot, Controlling Color
Aesthetics are extremely important to Marcella and his customers and he has come up with a number of techniques to control coloration and weld cosmetics. Marcella affects these elements of his welds through proper tungsten preparation (he uses a 1/16-inch two-percent thoriated tungsten), a custom tri-mix shielding gas, and the improved arc starts and advanced AC TIG controls found in the Dynasty 350.
“My biggest challenge with welding any material is sooting,” says Marcella. “I don’t like to see fuzz around the weld. And if there is going to be sooting around it, I prefer it to be white. Sometimes I’ll get a little bit of a dark or dingy colored sooting, especially on restarts.”
One of the features Marcella finds particularly helpful is the ability to fine-tune his arc starts/restarts. Conventional TIG machines generate a burst of current during starts that helps initiate the arc but also could severely damage the base metal. Inverters, conversely, allow welders to regulate that output down to a microsecond to the exact amount of starting amperage (as low as 1 amp) needed to light the arc without damaging the base material. It also allows the operator to further tailor/program the start based on the specific size of the tungsten.
“I like to start on a restart with a very low amount of amperage,” says Marcella. “I don’t want to just blast my part with a bunch of amperage real quick because that’s when it seems to soot a little bit more. When I changed it to the tungsten that I am running, it was very happy. The tungsten itself was real happy and it just started with a little more finesse.”
This ability to manage that arc start also eliminates the need to preheat the material in certain applications, which helps increase overall productivity.
“The speed at which you can weld, you can start welding immediately,” he says. “There’s no preheat. You strike your arc and you’re ready to rock—you’re in business right away. You cannot outrun this machine.”
Advanced AC Controls Reduce Heat Input, Give Operator More Control
TIG inverters like the Dynasty 350 provide operators with a spectrum of advanced AC capabilities not found in conventional TIG technology. For instance, old transformers typically allowed only the electrode negative (EN) portion of the cycle to be dialed up to 70 percent. Today’s inverters allow operators to set it up to 99 percent. This extended balance range allows for the arc to be fine-tuned according to base metal conditions in each application. It achieves faster travel speeds, narrows the weld bead, extends tungsten life, produces a smaller etched zone and permits the use of a smaller diameter tungsten to more precisely direct the heat into the joint.
“A lot of the times I’ll be welding on materials that I believe to be fairly thin, which are about 1/8-inch and .190-inch thick,” says Marcella. “What I do is fill material in and have the size of the bead be larger than what (are considered normal) because things are going to be re-machined afterwards, and radiuses and fillets will be machined into the part, so I need a decent cross-section of base material there. So at that point, I will adjust the balance of the machine to not dig quite as deep and not put as much heat into the part and create a wider bead than those materials would normally call for.”
“As far as warping goes, the balance control helps out a lot with that,” he adds. “When I weld the runners to the plenum, it creates an indentation in the plenum surface. With the inverter machines, you put much less heat into the part than on a typical machine, so your overall warping is quite less.”
The Dynasty 350 also gives operators the ability to independently set the electrode negative (EN) and electrode positive (EP) cycles to further fine-tune the arc. EP amperage dramatically affects the arc cleaning action (along with AC balance control).
“I do adjust the amperage independently if I’ve got into a very tight place or if my material thicknesses are very different,” says Marcella. “For instance, 1/8-inch to 1/2- or 5/8-inch thick and I need to keep my bead very small. At that point, I may put in more negative amperage and take some of the positive out, as well as mess around with the frequency adjustment to get what is needed for that particular weld.”
“(By increasing negative amperage) it narrows up the arc and just makes the accuracy better,” he adds. “A lot of what I do is cosmetic – we physically can’t melt or get a puddle into a bolt hole or into a machined section. It has to remain untouched, so the bead needs to be small. Those controls help out tremendously.”
The frequency adjustment Marcella mentioned is also critical to the process. Transformer-based TIG units are typically locked in at the line frequency: 60 hertz in North America and 50 hertz in other locations around the globe. New inverters give operators the ability to dial that in between 20 and 400 hertz. Higher frequencies limit the time that the arc expands on each half cycle, creating a narrow, focused arc with significantly better directional control.
“I adjust the frequency for narrowing or widening the puddle,” says Marcella. “The arc accuracy, the manipulation of the controls, the adjustments are endless. The controllability for personal weld styles is just phenomenal versus conventional welders.”
Wireless Remotes Reduce Hassle, Aide Technique
John Marcella doesn’t believe in Pulsed TIG welding. He’s a believer in riding the foot pedal and relying on his eye and craftsmanship to achieve the desired bead appearance. He also will typically weld in a weave pattern that helps achieve the cosmetic appearance he’s looking for as well as dissipate heat and push material where he wants it. Control is critical.
“It’s just a personal preference,” he says. “I want all of the control for what’s happening with the weld puddle. I don’t want the machine to do it because at every stage of when I’m in the weld, the heat that you’re putting into the part affects how it welds an inch down from where you are right now. There’s more heat in the part, so then less amperage is required for it. (I want control over) how quickly that puddle forms and how quickly that puddle chills. I want all of the control.”
For these reasons, accuracy of a remote TIG control is a paramount concern. Marcella was skeptical at first about how the wireless TIG remote would respond in real time to his constantly changing demands over the course of a single weld.
“When I got it, I was really concerned about its accuracy, to tell you the truth,” he says. “I like to rock my foot a lot to control how much heat is going into the part and manipulation of the weld puddle. So, how the accuracy of what I’m doing with my foot translates to the TIG torch is very important to me. I was very surprised because I can absolutely not tell any difference between the remote foot pedal and a standard corded foot pedal.”
Eliminating the cord in Marcella’s shop provides him with a couple of obvious benefits: improving safety by eliminating a tripping hazard and eliminating the hassle of cords getting twisted and tangled.
“The benefit is that I’m not tripping over the cord,” he adds. “When I’m building an intake manifold, it gets constructed on the cylinder heads on the engine block, so I’m constantly out of position and constantly moving around the engine. I find myself tripping over the cord, getting tangled, and it drives me absolutely crazy.”
Small, Compact, Efficient System Provides Extensive Benefits
In addition to the welding benefits of the system, an inverter-based TIG welder takes up substantially less space and uses less electricity than conventional TIG welders. Marcella has noticed these efficiencies with the Dynasty 350 w/ TIGRunner package.
“I want all the space I can get,” says Marcella. “I want the smallest machine possible. That way, I can tuck it wherever I want and not be tripping over it. If you have a big, bulky machine, it limits you to where you can put it and where it’s accessible. The smaller the machine, the better.”
“(And regarding electricity) the lights running in this shop cost more money to run than the welder does,” he says.
Overall, inverter technology has helped Marcella achieve his aesthetic requirements while also minimizing heat input and associated distortion. These capabilities, matched with his master craftsmanship, ensure that his manifolds continue to turn heads and add horsepower on drag strips from the U.S. to down under.
“I want my stuff to be the best out there, and that’s what I’m striving to do.”