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The B Engines: 350, 361, 383, and 400

by David Zatz

Chrysler Corporation’s first V8 engine tapped expertise in creating high-performance airplane motors; it was efficient, durable, powerful, costly, and slow to build. Soon, GM and Ford were selling cheap V8s hand over fist; and Chrysler rushed to design a new series of big-block V8s, ejecting hemispherical heads and other niceties.

361 wedge

Volume was key. Originally, Chrysler had figured that the next best thing to Hemi was a polyspherical head — but it turned out those had little, if any, advantage over the wedge design. They added complexity, weight, and bulk, while their lack of a “squish” area restricted compression. Chrysler followed GM with the wedge design.

Before making its own wedge engines, Dodge advertised the polyspherical design.

According to Willem Weertman, later head of Chrysler engine development, creation of the B series of big block V8 engines was led Robert S. Rarey, starting in 1955 — with a deadline of production for the new 1958 large cars. They had to be capable of class-leading power, so Rarey specified the largest space between cylinder centers of any Chrysler engine, ever — 4.8 inches. The basic design allowed for a 3.75 inch stroke, partly by having both a low-deck block (the LB series, usually just called “B,” with a top deck around 10 inches high) and a raised deck block (the RB series, with a 10.725 inch top deck height).

Used by DeSotoPlymouthDodge and DeSoto
Horsepower (gross)280305305
Carburetor2-barrelDual 4-barrel2-barrel

Source: Chrysler Engines, by Willem Weertman

To prevent flex, they used a deep skirt design and a five-bolt head bolt pattern for each cylinder, rather than the old four bolt setup; they used five main bearings. At the same time, they tried to reduce weight, using short exhaust ports (which also cut heat rejection to the antifreeze) and side-by-side intake ports (1.95 inches in diameter in 1958; the exhaust port was 1.6 inches).

361 and 413 engines

Past V8s had the oil pump and distributor in the rear of the engine; now, they went up front, to make clearance easier. The oil pump had a die-cast cover that also mounted the spin-on filter. Engineers tried to prevent steam pockets in the water jacket design, and let oil from the valve rockers flow directly into the tappet chamber into the sump, without drilled drain holes in the head or block.

super red ram

The new engine used stamped steel rocker arms, which Weertman called “unprecedented;” they started with flat steel stock rather than machining it. They also had hydraulic tappets, to avoid the need for regular adjustments (most of the original Hemis had used hydraulic tappets, too).

The “B” series wedge engines were launched in the 1958 cars, just seven years after the original Chrysler V8. Compared to the Hemi and Poly engines, it was light, simple, and cheap to build, yet still tough and sturdy.

For this one year, they were produced in 350 and 361 cubic inch versions, both large-bore, short-stroke designs, with 10:1 compression and identical valve diameters; the Plymouth dual-four-barrel version had a unique camshaft, but the DeSoto two and four barrel versions shared a cam. Made in a newly repurposed plant, they started rolling off the line just in time for the 1958 cars.

SonoRamic Commando

From the start, Plymouth, Dodge, and DeSoto shared the B-engine; Chrysler joined in a year later. This was part of a decision to have a single corporate engineering department for engines, after a bewildering variety of parts were created by the divisions as each produced a similar, but different, first-generation V8 engine with the same basic features.

Both the 350 and 361 had a fuel injected version in 1958 only. Very few “fuelies” were made, and precious few remain, since most had carburetors fitted.

The smallest, least potent B engine, the 1958 350 two-barrel — a one-year wonder used only by DeSoto — was rated at 280 horsepower and 380 pound-feet of torque, roughly matching the 1957 Plymouth Fury’s 318 V8 (290 hp, 325 pound-feet), equipped with two four-barrel carburetors. That was a good sign.

The Plymouth 350 four-barrel had 305 hp; the DeSoto Turboflash produced up to 295 hp; and the Dodge D-500, went up to 320 hp. The closely related 361 four-barrel, meanwhile, hit 305 horsepower and 400 pound-feet. This engine would last for many years, used in trucks long after the cars had moved on.

B engines were designed from the start to handle ever-increasing amounts of power, with drop-forged steel connecting rods and a forged crankshaft. Maintenance and repair were eased by the external oil pump, dry intake, and front-mounted distributor, along with an easily changed water pump.

turboflash 361 v8

Plymouth versions were called Golden Commando and Sonoramic Commando; Dodge versions, Super Red Ram (formerly used with the Hemi name) and D-500; DeSoto versions (starting in 1959), TurboFlash. These names were not necessarily used by anyone but marketers, but were, in some cases, emblazoned on the valve covers.

361 crankshaft

In 1959, the 361 was bored out, creating the most common Mopar performance engine for the next decade: the 383. The big bore allowed for larger (2.08”) intake valves, and the relatively short stroke helped it to be a free-revving engine as well as a free-breathing one. It launched on the 1959 DeSoto and Dodge cars. This first-year 383 had the same cam timing as the 1958-59 350 and 361 (except the Plymouth Fury version).

1959361 383
Carburetor2 barrel2 barrel

The DeSoto two-barrel version of the new 383 provided 305 horsepower and 410 pound-feet of torque, an inauspicious beginning. The four-barrel version, coded D-500 by Dodge for that year, was rated at 320 horsepower. DeSoto’s four-barrel (standard on the Fireflight) had an extra five horsepower and an extra five pound-feet, at least according to advertising; there may not have been any actual difference.

There was, though, a new attraction for the 1960 cars: a dual-four barrel version of the 361 and 383, with a long cross-ram setup.

d500 engine

The first major performance engine in the B series was the 1960 dual-carburetor D500 ram induction package, bringing up to 330 hp and 460 pound-feet of torque; it used a “cross-ram” manifold (the carburetors were on opposite sides of the engine from the cylinders they fed, crossing the valley, to gain the required tube length).

383 overhead view

The tubes had an internal length of 30 inches at first, for an added boost while passing on the highway; this was altered to 15 inches later, in some engines, for racing purposes.

torque curve

The compression ratios for the 361 were dropped from 10:1 to 9:1, for the 1961 cars, so owners could switch to regular fuel instead of premium. Power dropped somewhat, but the 383 was available for those who wanted more. The four-barrel 361 only lasted to the end of 1962; and the two-barrel was only used in cars through 1966.

Dodge V8s
Red Ram
D500 (1)D500 (2)Ram-Fire
Cubic Inches361361383383
Bore x Stroke4.12 x 3.384.12 x 3.384.25 x 3.384.25 x 3.38
Gross hp

295 @ 4,600320 330 @ 4,800325 @ 4,600
Max torque

390 @ 2,400420460 @ 2,800425 @ 2,800

Carburetion in 1961 was supplied by a two barrel Stromberg model WWC carburetor (3-188). This carburetor had a rubber-tipped needle valve in the float bowl, to prevent small dirt particles from causing problems; it had a two-stage set-up jet for good fuel flow at cruising speeds. The 1960 cars gained a three-stage metering rod.

3-stage metering rod

361 carburetors1961 was the first year for the closed crankcase ventilation system used on all cars sold in California, designed to painlessly reduce smog. A flexible tube connected a valve and a specially calibrated carburetor; the carburetor had a fitting just below the throttle blades into which the crankcase vapors were drawn by suction. From here they were drawn into the intake manifold for burning, leaving fewer vapors to be discharged into the atmosphere. All cars now use this system.

1968 dodge engines
Engines did not really have chrome-plated fans, oil filter covers, valve covers, or air cleaner housings.

Just as the 361 had been converted to run on regular gas in 1961, the two-barrel 383 was made compatible with regular gas in the 1965 cars, with compression dropping to 9.2:1. (Later, it would fall further — to 8.7:1 in the 1970 cars, and 8.5:1 a year later — to drop emissions).

In 1966, the truck 361 was rated at 186 horsepower at 4,000 rpm and included induction-hardened crankshaft journals, trimetal main and connecting rod bearings, hydraulic valve lifters, sodium-filled exhaust valves with Roto-Caps, and a chrome-alloy cast-iron block.

A special version of the 383 was created for the 1968 Plymouth Road Runner; it had heads, intake, camshaft, and exhaust manifolds from the 440 Super Commando. Those changes made it the fastest 383 ever, with 335 horsepower and 425 pound-feet of torque; the engine had a 9.5:1 compression ratio, single four-barrel carburetor, and a dual-snorkel air cleaner... and that was the base engine. The options were a 440 with three carburetors or a twin four-barrel 426 Hemi. This version of the 383 did not stay exclusive to the Road Runner for long.

1970 plymouth road runner badge

Starting in 1970, the 383’s peak power started to drop, as compression was lowered to cut back on emissions. The first drop was to 8.7:1 in 1970; then to 8.5:1 in the 1971 cars. The lower compression dropped horsepower ratings — but not nearly as much as changing the way horsepower was measured.

1971 383 four-barrel
(Road Runner)

Net horsepower ratings, adopted in 1972, caused many to think that horsepower took a sudden dive; in reality, horsepower was now measured with the air cleaner, water pump, alternator, muffler, and other “accessories.” The transition year, 1971, saw both gross and net numbers published for some engines in 1971 (see the charts).

1971 engines

In 1972, the Trenton Engine plant’s “B” line switched to a single new bore size, 4.34 inches, bringing the 383 up to 400 cubic inches; compression dropped down to 8.2:1 at the same time. The net power of this new engine was 190 hp and 310 pound-feet of torque with the two-barrel, and 255/340 with the four-barrel — a decent gain in power over the 1971 383. (Rick Ehrenberg of Mopar Action wrote that the original idea behind the 400 was to standardize all B and RB engines with a 4.32” bore; Marketing believed that the 400 would sell better than a 396. Hemi Andersen pointed out that the 360, which had been introduced in 1971, may have been too close to the 383 in displacement; the 400 would provide a better gap.)

The 400 had a ductile iron crankshaft, replacing the forged steel crank; this cut costs but, under normal conditions, was durable enough. Hemi Andersen wrote that changing the crankshaft also meant the need for an eccentric weight in the harmonic balancer, and the addition of a weight to the torque converter. In short, the engine needed to be externally balanced, while the past B and RB engines did not.

Starting in 1973, exhaust-valve seats were induction-hardened to allow use of lead-free fuels. In the hardening process, seats reach a temperature of 1700°F and are then allowed to air-cool. This hardened the valve seat surfaces to a depth of .05" to .08" which gives them greater resistance to wear than unhardened seats. The addition of the Chrysler electronic ignition system, which had been launched in some 1972 cars, eased maintenance requirements and increased reliability.

From 1973 to 1978, emissions equipment continued to become more complex, as engineers worked minor miracles to get carburetors to work more efficiently under all conditions. Fuel injectors were suggested, according to Allpar interviews, but rejected due to cost (which was most likely far less than the cost of the extra warranty work and lost customers). The 1975 addition of Electronic Lean Burn, the world’s first computerized spark advance system, helped somewhat.

400 V8

Two-barrel 400s were dropped in 1976, by which time their output was 175 hp and 300 pound-feet. In the 1978 cars and trucks, the 400-cubic-inch V-8 engines gained dual concentric throttle return springs in addition to a torsion throttle spring. Like all Chrysler V-8 engines, it gained an adapter so mechanics could use a magnetic probe to set the timing.

1977 440 V8 engine

The performance aspects of the B and RB engines had faded from 1971 until the last one was produced in August 1978. The last vehicle built with a Chrysler big block was a pickup truck made in 1979.

Mopar B and RB engine parts, and engine identification

361 V8Over three million 383 engines were produced through 1971, and over 750,000 440 engines were made, which makes many parts readily available.

Which engine do you have? Check the passenger side of the block, underneath the distributor, for a bit of smooth steel with a number code.

The first line has a letter for the year (D = 1968), followed by three digits for displacement (e.g. 440). The date (month and day) are on a line below, with an HP denoting High Performance where applicable. The tag will be just to the right of the distributor on RB engines. Special information (such as undersize crankshaft) may be next to the engine size.

Most B series engines have parts interchangeability, with a few exceptions. The RB required a wider intake manifold and larger crankshaft main bearing, and all B engines used a 3.38 stroke crank.

361 V8 engine

The two 383 engines (by Curtis Redgap)

The Chrysler 383 RB was an odd engine, created because Chrysler wanted a 383 but the factory could only produce enough 383 “B” engines for Dodge, Plymouth, and DeSoto. However, the new RB assembly line was under-used; so an RB 383 was created, in two and four barrel versions, for two years. When capacity constraints were removed, the RB 383 was replaced by the “normal” 383.

Other articles

Chrysler - Mopar big block V8 engine

Low Block4.063.38350High Block4.183.75413
 4.123.38361 4.253.75426
 4.253.38383 4.323.75440
 4.343.38400 4.03.75383


Specifications for 1958 Dodge models Red Ram
(325 Poly)
Super Red Ram
(350/361 B engine)
Type 90 deg V8 90 deg V8
Valve Arrangement In Head Single Rocker Shaft
Bore 3.69" 4.0625" (350)
4.125" (361)
Stroke 3.80" 3.375"
Piston Displacement (cu. inch) 325.0 Cu 350 and 361
Taxable Horsepower (AMA) 43.9 52.81 (350)
Compression Ratio 8.5 to 1 10 to 1
Compression Pressure (minimum 150 rpm,
plugs removed, wide open throttle)
90 (min) - 155 (max) 150 (min) - 180 (max)
Maximum Variation Between Cylinders 15 lbs 25 lbs
Firing order 1-8-4-3-6-5-7-2 1-8-4-3-6-5-7-2
Cylinder numbering (from drivers seat,
front to rear)
1-3-5-7 left, 2-4-6-8 right
Engine Lubrication: Pump Type Rotary Full Pressure
Camshaft drive
Rotary Full Pressure
Camshaft drive
Crankcase Capacity (qts) 5 4
Minimum Pump Pressure at 500 rpm 15 psi 15 psi
Operating Pressure at 40 to 50 mph 1500 RPM 50-65 lbs 45-70 lbs
Oil Filter Type Shunt; replaceable
Full Flow; replace
Cylinder Bore (std) 3.6875-3.6895" 4.0625-4.0845"
Cylinder Bore Out-of Round
(max. before reconditioning)
.005" .005"
Cylinder Bore taper (max. before reconditioning) .020" .010"
Max allowable over bore .060" .040"
Camshaft Drive Chain Chain
End play .002-.006" 002-.006"
Max allowable .010" .010"
Radial clearance .001-.003" .001-.003"
Max allowable .010" .005"
Camshaft chain
Number of links 68 50
Pitch .375" .50"
Width 1 1/8" .88"
Camshaft Journals Diameter and Length - #1 1.998-1.99 x 7/8"
#2 1.982-1.983 x 3/4"
#3 1.967-1.968 x 3/4"
#4 1.951-1.952 x 3/4"
#5 1.4355-1.4365 x 15/16"
Crankshaft Type Fully Counterbalanced
Bearings Steel Backed Babbitt
Thrust taken by No.3 main bearing
End Play .002-.007"
Max allowable .010"
Radial Clearance .0005-.0015"
Max allowable .0025"
Finish at rear Oil Seal Surface Diagonal Knurling
Main bearing Size Diameter and length No.1 2.50 x.73"
No.2 2.50 x.73"
No.3 2.50 x.72"
No.4 2.50 x.73"
No.5 2.50 x 1.19"
Main bearing Journals Diameter 2.5 2.625
Max Allowable Out of round .001" .001"
Max Allowable Taper .001" .001"
Center Bearing Run-Out
(total indicator reading)
when supported at front and rear main bearing
.002" .002"
Crankpin Journals
Diameter 2.2495-2.2505" 2.2495-2.2505"
Max Allowable Out of round .001" .001"
Max Allowable Taper .001" .001"
Connecting Rods
Length (center to center) 6.62 6.358
Weight (less bearing shell) 22.5 28.6
Bearings Steel Backed Babbitt Steel Backed Babbitt
Diameter and Length 2 1/4 x 13 /16" 2.375 x .927"
Clearance .0005-.0015" .0002-.0022"
Max allowable .0025" .0025"
Side Clearance .009-.017" .009-.017"
Connecting Rod Bushing Type Steel Backed Bronze none
Diameter and Length 1.110-1.125-.9217-.9220 ____
Pistons Conformatic with Steel Strut /
Horizontal Slot with Steel Band
Material Aluminium alloy tin coated
Land Clearance (in Bore) .027-.033" .042-.047"
Clearance (top of Skirt) .0005-.0015" .0005-.0015"
Weight (Standard through all oversize) 18.6 oz 705 gram
Ring Groove Width (upper) .032" .032"
(intermediate) .0790-.0800" .0790-.0800"
(lower) .1875-.1890" .1875-.1890"
Valves (intake)
Head Diameter 1.84" 1.95"
Length (overall) 4.31" 4.81"
Stem Diameter .37" .37"
Stem to Guide Clearance .002" .002"
Max. allowable .004" .004"
Face angle 45 deg 45 deg
Valves (Exhaust)
Head Diameter 1.47" 1.60"
Length (overall) 4.31" 4.81"
Stem Diameter .37" .37"
Stem to Guide Clearance .003" .003"
Max. allowable .006" .006"
Face angle 45 deg 45 deg
Valve guides
Type Cast in Head Cast in head
Size .374" .374"
Valve Springs
Pressure when compressed (Valve Closed) 1.69"-72 lbs 1.86"-75 to 85 lbs
Pressure when compressed (Valve Open) 1.31"-166lbs 1.47"-173 to 187 lbs
Valve spring installed height
(spring seat to retainer)
1 5/8 - 1 11/16" 1 55/64"

super red ram engine

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