Dodge 230 Flathead Engine for Sale | OEM L-Head Inline-6 (1942 to 1959)

Description

Engine Background

The Dodge 230 is the largest and final displacement of the Chrysler flathead inline-six family, an engine architecture that began production in 1933 and remained in continuous use for over 35 years in automotive, truck, military, and industrial applications. The 230 cubic inch displacement was standardized for both Dodge and Plymouth passenger cars starting in 1954, ending a decade-long period where Dodge used slightly different specifications from Plymouth. The basic internal design (four main bearings, solid lifters, L-head valve arrangement, single-barrel carburetor) remained essentially unchanged from the engine’s introduction through the end of civilian production in 1959.

The 230’s defining characteristic is its extremely long stroke: 4.625 inches compared to a 3.25 inch bore. This undersquare ratio was chosen deliberately for maximum low-rpm torque at minimal rpm, exactly what a 1950s family car, half-ton truck, or loaded Power Wagon needed. The engine produces its peak torque well below 2,000 rpm and is happiest operating between 1,200 and 2,500 rpm. Asking more than that from it is possible but increasingly inefficient and wears out the crank oiling system faster than Chrysler intended.

The 230 flathead powered every Dodge and Plymouth automobile from 1942 through 1959, plus the full range of Dodge D-series trucks, the legendary Power Wagon, and the wartime Dodge WC series military trucks. In military and industrial applications, the engine continued in production well into the 1970s. The Dodge Power Wagon (WM300) used the 251 cubic inch variant of this same flathead family through its final production year of 1968. Finding a tested, documented 230 flathead is a meaningful event for any serious vintage Dodge restoration.

When Replacement Becomes Necessary

• Valve train clatter that does not reduce after warm-up, valve lash out of adjustment (solid lifters require periodic manual adjustment unlike hydraulic lifters in later engines)
• Low compression across multiple cylinders, worn piston rings or scored cylinder walls on high-mileage examples
• Oil burning on all conditions, worn valve guides, a common flathead wear point since the valve stems are exposed to combustion gases and cylinder heat
• Overheating at low speeds, restricted cooling passages in aged flathead blocks, blocked radiator, or failed water pump
• Loss of oil pressure at idle, worn main bearings on high-mileage engines. The 230’s 4-bearing crank is vulnerable to oil pressure loss on neglected units.
• Hard starting in cold weather, typical flathead characteristic due to low compression ratios (6.7 to 8.0:1)

Known Issues We Document Before Shipping

• Valve guide wear, the most common 230 flathead maintenance concern: the L-head design exposes the valve stems to heat from the combustion chamber. Valve guides wear over time, causing oil consumption and rough running. We inspect for valve guide wear indicators before shipping.
• Main bearing oiling concern above 2,500 rpm: the 230’s crankshaft oiling system was designed for the engine’s intended low-rpm operating range. Sustained operation above 2,500 rpm can cause main bearing wear. We listen for bearing noise during pre-ship inspection.
• 218 versus 230 confusion: the earlier 218 cubic inch flathead (used 1942 to 1953) and the 230 share the same external dimensions and basic architecture. Block casting numbers distinguish them. The 218 has a 3.875-inch stroke versus the 230’s 4.625-inch stroke. We verify displacement on every order via casting number and stroke measurement.
• Aged seals and gaskets throughout: a 60-to-80-year-old engine has aged rubber and cork seals throughout. Plan a complete seal and gasket refresh at installation regardless of donor condition. Inexpensive insurance against post-install leaks.
• Babbitt versus insert bearing variants: the earliest 230 production used babbitt rod bearings; later production switched to insert bearings. For rebuilds, knowing which bearing type was originally fitted matters for parts sourcing. We document where determinable from external indicators.

230 Flathead Variants and Applications

Critical buyer information across the 1942 to 1959 civilian production run:

What Ships and What Does Not

Direct-Fit Vehicle Applications

Used OEM Versus Specialist Rebuild

For a vintage Dodge or Plymouth passenger car restoration or a Dodge D-series truck rebuild, a documented used 230 with compression results uniform and casting verified is the cost-effective path. For a show-quality restoration or a Power Wagon rebuild, a specialist rebuild with hard valve seats (for unleaded fuel), fresh valve guides, refreshed bearings, and new seals throughout is the better long-term investment. Specialist 230 flathead rebuilds typically run $4,500 to $8,000 from established Mopar vintage shops. Hard valve seat conversion adds approximately $400 to $700 to a rebuild and is essential for sustained unleaded fuel operation.

Inspection Workflow

• Compression test logged across all 6 cylinders with uniformity reported
• Displacement verified: 218 versus 230 via casting number and stroke measurement
• Year and application documented: passenger car, D-series truck, or Power Wagon donor
• Valve guide condition assessed where determinable
• Main bearing noise evaluated
• Babbitt versus insert bearing variant noted where determinable
• External oil leak survey at valve cover, side cover, timing cover, oil pan
• Cooling passage condition assessed where accessible

Pre-Purchase Buyer Notes

• Plan a hard valve seat conversion for unleaded fuel operation: the 230 was designed for leaded fuel. Modern unleaded fuel accelerates exhaust valve seat wear. A hard seat conversion (approximately $400 to $700 in machine work) at installation is essential for sustained modern fuel use. Skipping this leads to dropped valves and major engine damage.
• Refresh all seals and gaskets at installation: a 60-to-80-year-old engine has aged seals throughout. Source a complete gasket set in advance.
• Use detergent oil with care: original 230 flatheads were designed for non-detergent oil. Switching a heavily sludged engine to modern detergent oil can dislodge accumulated sludge and cause oil passage blockages. For engines with unknown service history, start with a conservative oil and inspect oil filter frequently in the first 1,000 miles.
• Match displacement to your vehicle: verify whether your vehicle originally had the 218 or 230 before ordering. The two engines are not directly interchangeable for show-quality restoration despite similar appearance.
• Plan for solid lifter adjustment: the 230 uses solid lifters requiring periodic manual lash adjustment (typically every 6,000 to 8,000 miles). Hydraulic lifter conversion kits exist but compromise originality for restoration purposes.

Why Buy From Part Nests

• Displacement verified: 218 versus 230 confirmed before payment via casting and stroke
• Year and donor application documented (passenger car, D-series truck, or Power Wagon)
• Babbitt versus insert bearing variant noted where determinable
• Valve guide condition assessed
• All 6 cylinders compression-tested with uniformity reported
• Cooling passage condition externally assessed
• No core return required
• Free freight delivery to every state
• 15 day replacement warranty against internal defects
• Call (240) 306-7051 to speak with someone who knows 230 versus 218 displacement identification, hard valve seat conversion requirements for unleaded fuel, and Power Wagon versus D-series truck variant differences