All about the AMBR-winning 1934 Chevy roadster and its LS Engine.

Beauty is More Than Skin Deep – A Look Under the Hood of America’s Most Beautiful Roadster for 2022

By Ron Ceridono

It’s no secret that one of the keys to seeing your name engraved on the America’s Most Beautiful Roadster (AMBR) trophy is to build a car with meticulous attention to detail. In the case of Jeff Breault’s 2022 AMBR winner “Lucille,” the phrase “attention to detail” doesn’t begin to describe the effort put into the construction of this 1934 Chevy roadster.

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Between the framerails of the Devlin Rod and Customs (DRC)–built AMBR winner is a Chevrolet LS3 with Dart heads, a custom stack injection system, one-off rocker covers, and a host of other custom pieces from Johnson’s Hot Rod Shop (JHRS).
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Breault has been a lifelong GM guy and the idea of building this roadster has been with him for years. He describes his vision as “A car that combines the look, feel, and attitude of a traditional roadster but benefits from cutting-edge engineering and technology.” When a suitable candidate to make this vision become a reality was found, the all-original ragtop was delivered to Tim Devlin and his crew at Devlin Rod and Customs (DRC) to begin its transformation from stocker to shocker.

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Carved from billet aluminum, JHRS created new rocker arm covers that serve a dual purpose.

While there are so many facets to this automotive gem to examine, here we’ve decided to focus on the engine (Apr. and May ’22 issues of Modern Rodding covered the bare metal chassis and body and the sheetmetal modifications). Collaborating on the engine with DRC was Alan Johnson and his team at Johnson’s Hot Rod Shop (JHRS) and father-son team Keith and Jeff Dorton of Automotive Specialists (AS).

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This engine sideview of one rocker cover shows the struts between the mounting bolt bosses and a groove for an O-ring that eliminates a gasket.

One of the goals for this project’s engine was to integrate the appearance of a vintage engine with the modern technology of a Chevrolet LS3. To that end JHRS created a fuel injection that looked to be mechanical but uses hidden, state-of-the-art electronics. Fuel delivery is controlled by a FAST XFI ECU that also manages the ignition timing and includes traction control. The intake manifold, injector bodies, and air horns were CAD modeled and produced on a 3-D printer finalize the look and fit of all the components.

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On the top sides of the rocker covers are provisions to mount the ignition coils.
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The unique cast intake manifold, designed by Johnson, is an open plenum design that allows all cylinders to feed from the same air supply rather than individual butterflies. This design also eliminates the need for vacuum lines from each injector body to supply the idle air control (IAC) manifold absolute pressure (MAP) sensor or other vacuum accessories. The eight throttle bodies and the velocity stacks with integral screens were all produced in-house at JHRS.

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Here the coils are in place. To hide them, faux rocker covers will be added.

To complete the vintage engine, ruse custom valve covers were machined that also mount the ignition coils. Topping those are covers reminiscent of the rocker covers found on early Rolls-Royce engines that were also CAD modeled and then machined from aluminum to conceal the coils. It’s a safe bet that when the JHRS CNC machines stopped whirring there was a dump truck load of aluminum chips from those items alone.

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With a new rocker cover in place the mismatch between it and the head is obvious, but it wouldn’t be that way for long.

Once JHRS was done with the fuel injection and cosmetic alternations to the engine it was turned over to AS for assembly. The block was bored to 4.125 inches and the stroke was increased to 4.125 inches with a Calles crankshaft resulting in 440 ci. For strength and longevity, the stock internals were swapped for connecting rods from Molnar and pistons from Mahle. The camshaft is a hydraulic roller, split duration design with 246 degrees of duration in the intake and 256 degrees on the exhaust. The cam makes music to a hot rodder’s ears at idle and helps make serious power. So much so that the original plan called for an engine with 500 hp but was exceeded by over 150 hp as the dyno sheet shows.

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The head’s mating surfaces with the valve covers were rounded and all the sharp edges were eliminated.

With the engine delivered to the crew at DRC, all the parts that appear to be chrome, including the throttle bodies and stacks, were plated in nickel then polished by Jon Wright’s CustomChrome Plating. The process requires pre-polishing, a copper plate followed by a dull nickel-plated surface, then polishing and careful color buffing to produce the final finish that is “warmer” than chrome.

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The unused accessory holes in the heads were welded shut then ground smooth. The results are the heads and valve covers appear to be one piece.
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When we say that DRC pays attention to every detail we’re not kidding. Buckets of ARP fasteners were delivered to aerospace machinist Roger and Cale Nelson at FMW Inc. where the heads of each were customized with a ball mill. Kansas Coatings applied the tungsten-colored Cerakote to the intake manifold, alternator headers, and other components. Finally, to complement the polished and plated components, DRC painted the block and heads in the Chevy’s original engine blue/gray color with Diamont basecoat from BASF, followed by several coats of clear. The rocker/coil covers were painted black.

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Like the fronts, all the unused holes in the sides of the heads were filled, then relief details were machined between the exhaust flanges to add a unique look.

We’ve only looked at the engine, but it is representative of the craftsmanship found throughout the car. Like we said, to win the perpetual AMBR trophy takes attention to detail attention. And in this case if detailing were a firecracker, this ’34 Chevy would be a nuclear explosion. MR

The faux valve covers that hide the coils were designed to replicate the look of a vintage engine, like the valve covers that were whittled out of a block of aluminum.
This is a rocker/coil cover viewed from the underside. The cutout on the left end is for the necessary wiring.
There are two hold-down clamps on each cover machined separate from the valve covers to allow for the application of different finishes (they will be plated while the covers will be painted).
DRC built a pair of tubes that hold the spark plug wires. To add detail, slots were added then filled with perforated metal that were secured with six rosette welds that were ground smooth.
Here one of the spark plug tubes is in place. Like the rest of the visible wiring, the plug wires have been cloth wrapped for a vintage look.
The intake manifold and all the injection system components were CAD modeled by JHRS. The intake was engineered to correct the inherent problems with individual butterfly per cylinder manifolds.
The intake manifold is a one-off casting that uses a common air intake plenum that allows all cylinders to feed from the same air supply rather than individual butterflies.
As the engine has a separate valley cover all the fuel injectors and wiring could be hidden on the underside of the manifold.
This view of the ports shows the location of the fuel injectors (arrows). Note that O-rings are again used to eliminate gaskets.
To hide the throttle position sensor JHRS machined this housing from aluminum that replicates a mechanical fuel injection barrel valve.
Here the TPS for the FAST fuel injection is in place. It will be operated by a lever connected to the throttle linkage and the wiring will go through a hole in the manifold.
The TPS for the EFI system mounts between the injector stacks just as a mechanical barrel valve would. An arrow points to the actuating lever that hooks to the throttle shafts.
Original mechanical-style fuel lines were added to help camouflage the throttle position sensor and maintain the mechanical injection look.
Keith and Jeff Dorton of Automotive Specialists (AS) oversaw the mechanical aspects of making the LS3 perform. Here Keith installs the Comp Cams push rods.
With the Comp Cams valvetrain components in place, Jeff installed an electric water pump for the dyno pulls then began assembling the rocker covers and ignition system.
Based on his years of experience, Keith chose the specs for the Comp Cams ’shaft and worked with JHRS on developing the EFI system.
More than a pretty face, on the dyno the 440ci Chevy recorded peaks of 654 hp and 618 lb-ft of torque.
Back at the DRC shop the engine was dropped between the Roadster Shop framerails. Hidden under the transmission tunnel are the fuel lines, idle air control (IAC), and oil pressure sender (the extra hole is for wiring).
Ultimate headers supplied the cast stainless steel exhaust header flanges and the tight radius header elbows.
DRC designed the headers that were built by Performance Welding Solutions to have the look of manifolds. JHRS produced the stainless steel exhaust clamps used throughout the system.
After grinding every surface smooth, DRC painted the engine in the original color found on early Chevrolet six-cylinder engines.
To convert from a serpentine system for more visually appropriate V-belts, an Edelbrock Victor Series water pump was installed with pulleys crafted by JHRS.
It’s the little things that make a difference, take this modified, early style OEM oil breather as an example.
DRC cut the breather apart, added three slots, then filled them with perforated metal screens.
The result is a breather that’s lots cooler than the chrome dome style seen in previous photos.
And the cool goes on, literally and figuratively. DRC created this one-off screened fan mount and shroud.

Sources

Devlin Rod and Customs
(316) 265-2088
devlinrodandcustoms.com

Johnson’s Hot Rod Shop
(256) 492-5989
johnsonshotrodshop.com

Automotive Specialists
(704) 786-0187
automotivespecialists.com

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