1930 LaSalle Series 340 Convertible Coupe: 340-Cubic-Inch L-Head V8

Cadillac built the 1930 LaSalle Series 340 around a 340-cubic-inch, 90-degree L-head V8 commonly rated at 90 horsepower. The line used a 134-inch wheelbase and a three-speed manual transmission, while the Convertible Coupe combined a folding roof with enclosed two-passenger coachwork and a separate luggage compartment.

LaSalle was Cadillac's companion marque, introduced for 1927 to serve buyers below the full Cadillac range while retaining Cadillac-built mechanical components and dealer support. The 1930 Series 340 followed the Series 328 and carried Harley Earl's design influence into the first full model year after the Wall Street crash, when expensive open cars became increasingly difficult to sell.

Best known for continuing the design-led character that made the early LaSalle central to General Motors styling history, the Series 340 also preserved the smooth, low-speed behavior of Cadillac's side-valve V8 in a shorter and less costly chassis than contemporary Cadillacs.

Quick Facts

The Series 340 designation identifies the 1930 LaSalle line and its nominal engine displacement. It should not be confused with a modern platform code or with the 1931 Series 345-A that succeeded it.

LaSalle production for 1930 is commonly listed at 14,995 cars across the Series 340 range. Surviving records do not consistently isolate Convertible Coupe production, so total Series 340 output should never be presented as the number built in this body style.

Why the Series 340 Convertible Coupe Matters

The Convertible Coupe concentrated three attributes that define the early LaSalle: Cadillac V8 construction, styling shaped under Harley Earl's direction, and open coachwork intended for personal rather than formal use. Its relatively low windshield, long hood, rear-mounted luggage area, and tightly fitted folding top gave it markedly different proportions from the upright sedans that accounted for much of normal luxury-car demand.

The car also records a sharp economic transition. It was conceived during the final phase of the 1920s luxury-car expansion but sold after the financial crash, as the American market for costly roadsters, phaetons, and convertible coupes contracted. That timing helps explain why correct open Series 340s command attention among collectors even though LaSalle sedans are encountered more frequently.

Historical Context and Development

Cadillac's Companion Marque

General Motors created LaSalle as a companion to Cadillac, following the corporation's 1920s strategy of filling price gaps between established divisions. Although marketed as a separate marque, LaSalle drew upon Cadillac engineering, manufacturing resources, and sales channels. It offered buyers Cadillac-associated refinement without duplicating the size, price, or formal image of the senior cars.

The original 1927 LaSalle was designed under Harley Earl, whose work persuaded General Motors to establish the Art and Colour Section. By 1930, visual design had become a coordinated corporate discipline rather than an incidental layer applied after engineering. The Series 340's deep radiator shell, long hood, flowing front fenders, restrained brightwork, and carefully balanced body volumes reflected that change.

From Series 328 to Series 340

The Series 340 replaced the 1929 Series 328. Its enlarged V8 supplied the torque required by a substantial ladder-frame automobile, while Cadillac's engineering priorities remained smoothness, quiet operation, flexible high-gear running, and manageable controls rather than competition performance.

Packard, Lincoln, Pierce-Arrow, Marmon, and Chrysler's Imperial line supplied the most relevant American context. LaSalle did not need a racing or homologation derivative to make its case. Styling, eight-cylinder operation, and Cadillac dealer backing were its commercial arguments, especially against premium cars still relying upon more conservative body design.

Design and Proportion

The Convertible Coupe's roof folded behind a compact passenger compartment, leaving the long hood and rear deck visually dominant. A tall, narrow grille, drum-shaped headlamps, sweeping separate fenders, running boards, and wire wheels identify its period, while optional or accessory sidemounted spares can substantially alter the profile.

Surviving cars display considerable variation in lamps, mirrors, trunks, wheel colors, whitewall tires, and radiator ornaments. Some differences reflect period accessories, but others result from restorations assembled around later tastes. A visually attractive car is not necessarily an accurately restored one.

Engine and Drivetrain

The Series 340 used Cadillac's established 90-degree V8 format with side valves, also described as an L-head or flathead layout. A single carburetor fed the engine, while battery-and-coil ignition with a distributor served all eight cylinders. Water cooling employed a belt-driven fan and pump-assisted circulation through the radiator.

The side-valve arrangement sacrificed the breathing potential of later overhead-valve engines but provided compact cylinder heads, low mechanical noise, and useful torque at modest engine speed. Pressure lubrication protected the main rotating assembly, although the oiling system, bearing clearances, and cooling passages require specialist attention during a modern rebuild.

A dry-plate clutch connected the V8 to a three-speed manual gearbox. Drive then passed through a propeller shaft to a live rear axle. The transmission is commonly described as synchronized, but the condition and exact internal specification of an individual gearbox should be confirmed before purchase because later units and mixed internal parts appear in restored cars.

The core factory specifications are concise. Compression ratio, peak torque, and maximum safe engine speed are not reproduced here because surviving references do not present those figures with sufficient consistency.

For restoration purposes, displacement and external appearance are only the beginning. Carburetor type, distributor body, manifolds, air cleaner, hose clamps, generator, starter, and routing of fuel and ignition lines all affect authenticity. Substituted postwar electrical components can make a car easier to operate while materially reducing engine-bay correctness.

Chassis, Suspension, and Braking

The Series 340 was constructed around a separate steel frame with the body mounted above it, the conventional American luxury-car method of the period. A rigid front axle and live rear axle were located by semi-elliptic leaf springs. The arrangement valued durability and predictable wheel control on rough roads over the low unsprung weight associated with later independent suspension.

Manual steering and mechanically operated four-wheel drum brakes demand more physical input than hydraulic systems fitted to later cars. Brake performance depends heavily upon equalized linkage, correctly arced linings, round drums, sound cross-shafts, and minimal wear in pins and clevises. A poorly adjusted example may pull severely even when every wheel technically has a functioning brake.

The following table records the principal chassis details useful when distinguishing a Series 340 from adjacent LaSalle generations.

Open bodywork places greater demands on the frame, body mounts, sills, and door structure because no fixed roof helps resist twist. Door fit that changes when the car is raised can expose weakened wood framing, distorted mounts, or frame damage concealed beneath fresh paint.

Driving Experience and Road Behavior

A properly sorted Series 340 should pull away with a smooth, deliberate surge rather than a burst of revs. Its large-displacement V8 was intended to carry high gear at low road speed, and the accelerator should produce progressive torque without coughing, detonation, or fuel starvation. Persistent vibration points toward ignition faults, incorrect engine mounting, driveline wear, or a rebuild whose rotating assembly was not properly balanced.

At parking speed the steering is heavy, particularly with underinflated tires, but effort falls once the car is moving. The long wheelbase encourages stable progress and measured directional changes. Rough surfaces are absorbed with the broad, slow movement typical of leaf-sprung luxury cars, although worn shackles and ineffective dampers permit excessive roll, axle movement, and repeated pitching.

The gearbox rewards an unhurried hand. Even where synchronization is present and effective, deliberate shifts reduce stress on aged gears and selector parts. Brake pedal effort is substantial by modern standards, and a driver must anticipate stops, but a correctly rebuilt and equalized mechanical system should stop the car in a straight line from speeds appropriate to its period.

Identification and Originality

Serial, Engine, and Body Records

A 1930 LaSalle does not possess a modern 17-character VIN. Identification depends upon the original serial or chassis information, engine number, coachbuilder body plate, and documentary evidence. Buyers should record every stamping and plate before restoration, then compare them with recognized Cadillac-LaSalle club references or archival material rather than relying on an undocumented online decoder.

The Series 340 identity must agree with the 1930 chassis, 340-cu-in engine type, wheelbase, and body construction. The Fisher or Fleetwood plate, where fitted and intact, can provide body-style and sequential body information, but it is not a substitute for the chassis identifier. Reproduction identification plates exist, so fresh rivets, mismatched typography, or a plate mounted over restored paint deserve scrutiny.

What Matching Numbers Means on a 1930 LaSalle

The modern phrase “matching numbers” can mislead when applied to a prewar Cadillac product. The relevant question is whether the engine, chassis identification, body plate, and major assemblies correspond with factory or club records and with one another. It should not be assumed that every component carries a matching derivative number in the postwar sense.

Engine changes were practical repairs when these cars were ordinary used automobiles. A correct-type 340 engine is preferable to an obvious later replacement, but an original unit supported by period paperwork, old registrations, service records, or long-term ownership history has greater evidentiary value.

Correct Equipment and Finishes

Restorers should verify the radiator shell, grille texture, hood doors or louvers, lamp bodies, dashboard instruments, steering wheel, door hardware, windshield frame, top irons, and wheel specification against 1930 literature and unrestored reference cars. Cadillac and LaSalle parts from neighboring years can appear deceptively similar while differing in dimensions, mounting points, or finish.

Factory paint information should be established from period color literature, surviving hidden paint, body records when available, and specialist research. Modern metallic colors, excessive chrome, incorrect vinyl upholstery, bright plated engine parts, and broad whitewall tires can produce a fashionable restoration that does not reflect 1930 factory practice. Date coding was not applied to every component in the manner familiar to postwar collectors, so originality requires a broader examination of construction, finish, and provenance.

Variant and Body-Style Breakdown

Series 340 variants were differentiated chiefly by coachwork rather than engine tune. Cadillac did not catalog a racing, homologation, or higher-output version of the Convertible Coupe.

Body-style terminology should be checked against the original body plate and sales literature. “Roadster” and “Convertible Coupe” are not interchangeable descriptions, even when an auction catalog or registration document uses them loosely. Exact output by individual body style is not consistently documented in widely available production records.

Performance and Dimensional Specifications

Factory literature emphasized power, wheelbase, appointments, and construction rather than acceleration testing. Standardized 0-to-60-mph and quarter-mile figures are not reliably documented for the Convertible Coupe, and quoted top speeds often originate from later estimates rather than instrumented period tests.

Published weights differ by body style and equipment, particularly where sidemounts, trunks, and other accessories are fitted. A generic Series 340 weight should therefore not be assigned to a specific Convertible Coupe without a corresponding factory body-style listing.

Compared With Related LaSalle Models

1929 Series 328

The 1929 Series 328 is the immediate predecessor and uses the earlier nominal 328-cu-in displacement designation. Similar styling themes and the interchange of parts during old restorations can confuse identification, but engine type, model-year details, plates, and chassis dimensions must be evaluated together. A car titled as a 1930 model is not automatically a Series 340 if its primary identifiers indicate otherwise.

1931 Series 345-A

For 1931, the Series 345-A replaced the Series 340 and brought another displacement designation as well as revised styling and detail equipment. Components from a 345-A may be physically adaptable, yet visible substitutions can compromise a 1930 restoration. Radiator, hood, lighting, instrumentation, and engine accessories deserve particular comparison.

Contemporary Cadillac V8 Models

A 1930 Cadillac V8 was a senior automobile with different series identification, chassis dimensions, pricing, and available coachwork. The shared corporate engineering lineage does not make Cadillac and LaSalle badges interchangeable. Cars assembled from LaSalle chassis parts and Cadillac trim should be treated as modified vehicles unless documentation establishes a period body or equipment change.

Ownership and Restoration Notes

Mechanical components are robust by the standards of their day, but age, deferred maintenance, and poor prior machine work create expensive problems. A V8 rebuild may require specialist bearing work, crankshaft inspection, valve and guide repair, replacement pistons, water-jacket cleaning, and reconstruction of accessories that cannot simply be ordered from a modern parts catalog.

Cooling faults often arise from sediment in the block, a restricted radiator core, worn water-pump components, incorrect ignition timing, or a lean fuel mixture. Overheating should not be dismissed as normal prewar behavior. Oil pressure, hot idle quality, exhaust smoke, coolant contamination, and crankcase noise should all be assessed after a meaningful road test.

The transmission and rear axle require attention to bearings, seals, gear wear, and lubricant compatibility. Clutch chatter may originate in contaminated friction material, distorted components, worn mountings, or excessive driveline movement. The mechanical brake system must be restored as a complete linkage rather than adjusted one wheel at a time to conceal worn pivots.

Body restoration can exceed the cost and complexity of mechanical work. The Convertible Coupe combines steel panels with structural wood, a folding top mechanism, framed glass, special door hardware, and open-car trim. Rotten sill and pillar wood can remain hidden beneath paint, while a missing windshield frame, top iron, latch, or garnish molding may take years to replace.

Routine service should follow period lubrication charts, with frequent attention to chassis points, steering joints, spring shackles, wheel bearings, fluid levels, ignition adjustment, and brake linkage. Low annual mileage does not eliminate the need for service because condensation, old fuel, hardened grease, and brake-linkage corrosion develop while the car is parked.

Buyer and Inspection Points

A credible inspection begins with identity and body structure, not paint gloss. The following checks address the areas most likely to affect authenticity, safety, and restoration cost.

A running but incomplete car can be a more difficult proposition than a non-running complete one. Major engine parts can be manufactured or repaired at a price, while a missing open-car molding or top mechanism may have no straightforward replacement.

Collector and Market Relevance

Collectors value the Series 340 Convertible Coupe for its open coachwork, Cadillac-built V8, and direct connection to the early years of GM's formal styling organization. Desirability depends heavily upon body authenticity, completeness, structural quality, and the accuracy of the restoration. A documented car retaining its original body, chassis identity, and major mechanical assemblies carries a different historical value from an attractive reconstruction.

There was no significant factory motorsport program attached to this model, and competition history is not the source of its appeal. Its importance lies instead in American industrial design and the companion-marque strategy, backed by the engineering resources of Cadillac during a period when styling became a planned part of mass production.

Auction interest generally favors open LaSalles over equivalent sedans, but headline sales cannot be applied indiscriminately. Body authenticity, restoration age, concours history, mechanical usability, and provenance create wide differences between superficially similar cars. Exact Convertible Coupe production is not consistently documented, so claims of extreme numerical rarity require evidence.

Cultural Relevance

LaSalle's strongest cultural association is Harley Earl and the transformation of automobile styling inside General Motors. The marque demonstrated that proportion, color, surface treatment, and brand identity could be directed by a permanent design organization. The 1930 Series 340 belongs to the first generation shaped after that institutional change had begun.

Cadillac and LaSalle clubs provide much of the surviving technical knowledge, parts exchange, archival research, and judging expertise surrounding these automobiles. The Series 340 has little meaningful period tuning culture and no homologation narrative. Its preservation community is centered on historical accuracy, touring reliability, formal judging, and the reconstruction of factory finishes.

Frequently Asked Questions

What engine is in the 1930 LaSalle Series 340?

It uses a Cadillac-built, naturally aspirated 340-cubic-inch 90-degree V8 with side valves. Period specifications commonly list output at 90 horsepower.

Was the Series 340 built only in 1930?

Yes. The Series 340 designation applies to the 1930 LaSalle line. It followed the 1929 Series 328 and was replaced by the 1931 Series 345-A.

How can a genuine Series 340 Convertible Coupe be identified?

Identification requires the chassis or serial information, engine number, body plate, 134-inch-wheelbase chassis, correct engine type, and physical evidence of genuine Convertible Coupe coachwork. Those details should be checked against recognized Cadillac-LaSalle references rather than a modern VIN decoder.

How many 1930 LaSalle Convertible Coupes were built?

Total 1930 LaSalle production is commonly listed at 14,995 Series 340 cars, but surviving published records do not consistently provide a defensible production total for the Convertible Coupe alone.

What are the main problems when restoring a Series 340 Convertible Coupe?

The largest risks are decayed structural wood, frame or body-mount distortion, missing open-car hardware, an incorrect engine, cooling-system blockage, worn mechanical-brake linkage, and mixed components from neighboring model years. Body-specific pieces can be harder to replace than internal engine parts.

Are parts available for a 1930 LaSalle Series 340?

Club networks, specialist suppliers, used-part collections, and limited reproductions support these cars, but availability is uneven. Service items and some mechanical components are obtainable, while body trim, top hardware, instruments, castings, and model-year-specific fittings may require restoration or fabrication.

What makes the 1930 LaSalle Convertible Coupe collectible?

It combines scarce open coachwork with Cadillac's 340-cu-in V8 and styling from the early Harley Earl period at General Motors. Collectors place particular weight on genuine body identity, complete hardware, sound structural wood, correct finishes, and documented provenance.

Collector Takeaway

The 1930 LaSalle Series 340 Convertible Coupe deserves attention because its engineering and coachwork explain the early LaSalle idea without decoration from a later racing myth. Cadillac supplied the V8, chassis, and dealer infrastructure, while Harley Earl's organization gave the car proportions that made a separate marque visually credible.

Buy the body, identity, and documentation before buying the paint. A complete, structurally honest Series 340 Convertible Coupe preserves one of General Motors' clearest early demonstrations that design could sell an automobile as decisively as cylinder count, and its 340-cu-in V8 gives that argument the mechanical substance to survive beyond the showroom.