For 1958 Chrysler Corporation discarded the brand-based V-8s in favor of corporate wedge engines. Plymouth retained the Poly V-8 as an entry-level engine but used the new B engine in all upscale and performance  applications. Chrysler would retain the Hemi until 1959 when the new “RB” 413 CID  came on line. These “B” and “RB” engine would remain in use through the end of the V-8 era.

The 1958 DeSoto Fireflite and Firedome (right) models had similar front facias, but the Firesweep (left) used the Dodge front with a DeSoto bumper/grille. Note the chrome surround on the Firesweep swept up over the headlights across the bottom of the hood and over the other headlight. The Fireflite/Firedome had individual cutouts for the headlights and no chrome lip on the hood. Note the difference is in the front fenders – Firesweep smooth sided, others with creases.

The new grille now filled a majority of the area and had a honeycomb grille insert, a dip in the center of the middle grille bar and round parking lights at the outboard ends. Fireflite/Firedome models used the bullet bumperettes now outward from the center.

1958 DeSoto wagons and regular models changed little at the rear. As in 1957, the taillight bezels were squared off at the bottom on the standard cars and curved on the wagons. Both used the same bumpers as in 1957. The notable difference was the exhaust extensions which had a dimple at the top giving an appearance of four outlets. All else was unchanged.

All 1958 DeSotos used the same side trim and two-tone paint inserts on all hardtops and convertibles as standard. This same insert was optional on all 4-doors. The chrome insert in the “C” pillar was standard on all hardtops. Significant differences were that the Fireflite and Adventurer had a special medallion on the front fender and used ‘wind splits” on the top of the front fenders (optional on Firedome models). All had their model name in script at the rear. The Adventurer had a special panel insert over the painted area with “Adventurer” in gold script (insert).

FIREDOME SERIES LS2-M (8-Cylinder wedge-head V-8): The Firedome was basically unchanged for 1958. “Firedome” nameplates were placed on the rear fenders. All Firedome models had the same side trim as the lower priced Firesweep models, but the front molding treatment was different. “Windsplit” ornaments for tops of front fenders were an option.

The interior was upgraded over the Firesweep. Upholstery materials were defined as “Frontier Homespun” fabric (cowboys were a big thing in 1958) in combination with grained vinyl, all colored to harmonize with exterior finish. Firedome models used the new “B” series V-8 with an increased displacement to 361 CID.

The Firedome was available as a 4-door Sedan, 4-door Hardtop, 2-door Hardtop, and Convertible.

FIREFLITE SERIES LS3-H (8-Cylinder wedge-head V-8): The top rung DeSoto series was identified by “Fireflite” rear fender nameplates and a distinctive upper body side molding which extended the full length of the car and incorporated special medallions on sides of front fenders. “Windsplit” fender-top ornaments were standard equipment. “Color Sweep” trim was standard on hardtops and convertibles.

Fireflite interiors were a step up from the Firedome and leather was an option on some models. The Fireflites used the same new “B” series 361 CID V-8 as the Firedome but fitted with a 4-barrel carburetor.

A springtime trim package was released as an option for all models except Adventurers and featured two groups of four vertical bright metal deck lid slashes affixed one group to each side of the recessed license plate housing. New exterior colors were announced about the same time. Fireflite interiors were done in metallic Damask and vinyl and incorporated integrated arm rests with aluminum finish recesses above.

The Fireflite was available was available as a 4-door Sedan, 4-door Hardtop, 2-door Hardtop, Convertible and Station Wagon.

ADVENTURER SERIES LS3-S (8-Cylinder wedge-head V-8):  The Adventurer models were still a Fireflite sub-series, but pure performance and luxury. Like the Fireflites, these high-performance cars came standard with Torqueflite transmission, backup lamps and full wheel covers, but there were some other extras that were standard: power brakes, dual exhausts, dual rear radio antenna, dual outside rear view mirrors, white sidewall tires, dashboard safety panel and special paint and trim. The latter included gold highlight surrounds, twin groupings of four deck lid bars, triangular rear side sweep inserts and special upholstery.

The Adventurer also used the same new “B” series 361 CID V-8, but was fitted with dual 4-barrel carburetors, and a camshaft upgrade but no cylinder head/valve increases over the Fireflight. It was rated at 345 HP. A radical new option was an electronic fuel injection system manufactured by Bendix which increased the output to 355 HP. Cars with fuel injection had special nameplates above the front fender medallions. Most were later recalled to the factory and converted back to Adventurer “standard” dual-quad carburetors due to the fuel injection system’s unreliability.

The Adventurer was now available as a 2-door Hardtop and Convertible.

Firesweep Power Pack V-8: Overhead valves. Wedge cylinder head. Cast iron block. Five main bearings.
Displacement: 350 CID.
Bore and stroke: 4.06″ x 3.38″.
Compression ratio: 10.0:1.
Horsepower: 295 @ 4600 RPM.
Torque: 385 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 252°, Exhaust 252°, Overlap 30°, Lift (Intake) 0.390″ (Exhaust) 0.390″.
Carburetor: Manual Trans – Carter AFB four-barrel 2773S; Auto Trans – Carter AFB four-barrel 2642S.
Exhaust: Dual as standard equipment.

Firedome Series V-8: Overhead valves. Wedge Cylinder Heads. Cast iron block. Five main bearings.
Displacement: 361 CID.
Bore and stroke: 4.12″ x 3.38″.
Compression ratio: 10.0:1.
Horsepower: 295 @ 4600 RPM.
Torque: 390 @ 2400 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 252° Exhaust 252°, Overlap 30°, Lift (Intake) 0.389″ (Exhaust) 0.389″.
Carburetor: Manual Trans – Ball & Ball two-barrel BBD 2772S; Auto Trans – Ball & Ball two-barrel BBD 2637S.

Fireflite V-8: Overhead valves. Wedge Cylinder Heads. Cast iron block. Five main bearings.
Displacement: 361 CID.
Bore and stroke: 4.12″ x 3.38″.
Compression ratio: 10.0:1.
Horsepower: 305 @ 4600 RPM.
Torque: 400 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 252° Exhaust 252°, Overlap 30°, Lift (Intake) 0.389″ (Exhaust) 0.389″.
Carburetor: Carter Four-barrel AFB Model 2642S.
Exhaust: Convertible standard with Dual Exhausts – Optional on others, except station wagon.

Adventurer V-8: Overhead valves. Wedge Cylinder Heads. Cast iron block. Five main bearings.
Displacement: 361 CID.
Bore and stroke: 4.12″ x 3.38″.
Compression ratio: 10.25:1.
Horsepower: 345 @ 5000 RPM.
Torque: 400 @ 3600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 260° Exhaust 260°, Overlap 42°, Lift (Intake) 0.390″ (Exhaust) 0.390″.
Carburetors: two 4-barrel Carter AFB – front number 2652S; rear number 2653S.
Exhaust: Dual.

Adventurer Fuel Injected V-8: Overhead valves. Wedge Cylinder Heads. Cast iron block. Five main bearings.
Displacement: 361 CID.
Bore and stroke: 4.12″ x 3.38″.
Compression ratio: 10.25:1.
Horsepower: 355 @ 5000 RPM.
Torque: 400 @ 3600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 260° Exhaust 260°, Overlap 42°, Lift (Intake) 0.390″ (Exhaust) 0.390″.
Induction: Bendix Electronic Fuel Injection. NOTE: See page 6 addendum of the 1958 DeSoto AMA Specifications Sheets for information on the “Electrojector” fuel injection system. HERE.
Exhaust: Dual.