B (as in “big”) V8 engines

Despite our headline, the B in “B engines” did not mean “big.”

The creation story

Chrysler’s first V8 engines (such as the 392 shown below) were a success, but they were only intended for high-end, relatively pricey cars. As more and more customers demanded eight cylinders, though, Chrysler Corporation could not make enough of their hemispherical-head powerplants.

Chrysler 1957 392 Hemi FirePower V8 engine

Engineers went to work; their first move was a series of engines that were basically the same, but with polyspherical-chamber heads which allowed them to jettison the double rockers. More was needed, though, especially with Plymouth itching to get their own V8s. Plymouth’s sales eclipsed Dodge, Chrysler, and DeSoto put together, but Plymouths sold against Chevrolets and Fords, so cost and quantity were both issues. The solution, for now, was redesigning the company’s original V8 engines to make them simpler and easier to build—creating the “A” engines.

Get updates

Free: Get an email when we post a new article!

There the matter may have rested, except that the original dual-rocker block was never designed for the larger bores they would eventually need to get beyond 392 cubic inches. Thus, they created a brand new series of engines, dubbed “B,” to grow with the competition.

These were the first engines created by a new corporate Engine Division; every brand would use the engines they produced. The company’s original V8s were fine engines, but Dodge, DeSoto, and Chrysler each had different versions whose internal parts did not always interchange.

wedge combustion chamber (B-engines)

The first question for the engineers was whether to keep the “poly” design or move to the wedge design. Being Chrysler, they went to the test equipment—and found out that the two designs had roughly the same performance. Because engines with the wedge chambers (which had in-line valves, rather than the divergent valves of the poly heads) were lighter, more compact, and cheaper to make, the company used that design.

The project was led by Robert S. Rarey, who would also lead the creation of the famed slant six; Rarey had been a test engineer for the Hemi aircraft engine in World War II, and had been a Plymouth engine engineer. Willem Weertman, the legendary Chrysler engine designer, wrote in his book Chrysler Engines (SAE) that “Rarey rose to the challenge, directing his highly regarded overall engineering acumen to the task, along with his customery personal vigor.”

361 V8 (b-engine)

With guidance from the product planners, lead designer Fred Shrimton and advance engine design supervisor Ray Latham created a design with a large block, having 4.8 inches between the cylinder centers (the largest of any engine ever made by Chrysler) to support massive cylinder bores in the future. A deep skirt was set to go three inches below the crank centerline, to keep it stiff under heavy loads. Planning ahead for long strokes, the team assumed a low deck version with a 9.98 inch high top deck and a raised deck (to be coded RB, raised-deck B) version with a 10.725 inch top deck; they planned clearance for connecting rods to handle a 3.75 inch stroke. (Technically, the B engine was the LB, but today it’s almost universally called B.)

[table id=3 /]

To avoid steam pockets, the water jacket had a horizontal roof; below it was the antifreeze, above it was the oil from the valve rockers, which could flow into the tappet chamber and then the sump. A good deal of thought was given to weight reduction, including having short exhaust ports (so the exhaust manifolds were close to the heads), side-by-side intake ports, and using a single embossed sheet metal gasket to seal the joints between the heads and intake. Knowing they would have large bore versions, the engineers went from 10 to 17 bolts to attach the heads; they also used drop-forged steel connecting rods and a forged crank.

The team did not just adjust their current engines; they moved the oil pump and distributor from the left/rear area (on the Hemi) so the oil pump would be mounted on the front bottom left of the block, and the distributor would be on the front top right.  The idea was that the distributor could be further from the ventilation equipment at the firewall, and the oil pan sump could be shaped as needed to clear the tie rods. The oil pump’s aluminum cover was also the filter mount. Revolutionary new stamped steel rocker arms replaced the normal machined ones, relying on a supplier to do the research and tool up in time; these turned out to be a success.

The B-series engines arrive

The engineering of the B engines had started after 1955; they were put into the 1958 cars, and by then, the team was busy working on the forthcoming slant six. The first engines were not much of a strain on the new design, coming out in 350 and 361 cubic inch versions; the 350 was mainly useful in future years to win bets with Chevy lovers, while the 361 would be made for many years, for trucks and motor homes. Both these engines had relatively large bores, with short strokes, and 10:1 compression. DeSoto had two-barrel and four-barrel versions, sharing a cam; Plymouth also had a uniquely cammed dual-four-barrel version, making a serious splash in the hot Plymouth Fury.

All horsepower figures before 1971 are gross numbers, without any accessories such as alternators/generators, mufflers, water pumps, or air cleaners. You can get a rough idea of the difference by looking at 1971 figures, when both gross and net numbers were supplied. For example, the 1971 383 four-barrel had 300 gross horsepower, and 250 net horsepower; torque was 410 (gross) and 325 (net) pound-feet. There were no changes other than measurement. This means that the 1971 383 four-barrel produced less horsepower, in reality, than 2021’s Pentastar V6, albeit with far greater torque.

The least powerful of these 1958 engines was the 350 two-barrel used by DeSoto only, generating 280 horsepower and 380 pound-feet of torque. To provide some perspective, the hot 1957 Plymouth Fury used a 318 cubic inch A-series (wedge) V8, with two four-barrel carburetors; while it had ten more horsepower, torque was just 325 pound-feet. The B-engine was clearly outclassing the A-engines in power; especially when one considers that the Plymouth 350 four-barrel generated 305 horsepower, the DeSoto Turboflash produced 295, and the Dodge D-500 made 320.

The 361, in its first year, produced 305 horsepower and 400 pound-feet of torque with its four-barrel carburetor. There was also an electronic fuel injection setup, produced by Bendix, for both engines; a factory option for 1958 cars, it was incredibly prescient but materials technology was not quite there, and most of these were replaced by carburetors. One or two were re-created and are still running. These 1958 systems had just about everything 1980s multiple-port injection would, except for heat-and-vibration-resistant electronics.

Incidentally, though the engines were essentially identical other than (sometimes) camshafts and carburetors, each division had their own name for them. Plymouth chose Golden Commando and, later, Sonoramic Commando; Dodge chose Super Red Ram (also used on the prior Hemi series) and D-500 (again, a carry-over); DeSoto, starting in 1959, went with TurboFlash. Sometimes the names were put onto the valve covers, sometimes they just made it into ads or brochures.

Throughout the B-engines’ run, trucks got special versions with induction-hardened crankshaft journals, hydraulic valve lifters, sodium-filled exhaust valves designed to rotate, a chrome-alloy cast-iron block, and special rod bearings.

Upgrades and improvements: cross-ram wedge and more

Starting in 1959, Chrysler started making its most common performance engine of the 1960s: the 383, a larger-bore version of the 361. Boring the cylinders provided space for 2.08-inch intake valves. For 1959, cam timing was the same as the 350 and 361 (except for the Fury’s 361 unique cam). As in future years, there were two carburetors, with a two-barrel for economy (305 horsepower, 410 pound-feet—nearly identical to the 361) and a four-barrel for performance, with 320 horsepower on the Dodge and 325 horsepower on the DeSoto Fireflight.

Parts interchangeability is excellent within the B-engines, by design. The RB can swap some parts, but not all of them; it has a larger crank main bearing and a wider intake, with other parts altered to lengthen the stroke.
cross-ram wedge engine

1960 brought a long-ram setup; to make the manifold tubes 30 inches long, which created an air-pressure effect providing a degree of supercharging at certain revolutions, the engineers had each carburetor and air cleaner feed the cylinders on the opposite side of the engine bay. The arching, crossing tubes were a beautiful sight, though the 30 inch tuning was not ideal for racing (it was meant to help in highway acceleration). The “cross-ram” setup brought Dodge 330 horsepower and 460 pound-feet of torque. Two-barrel cars, meanwhile, got a three-stage metering rod for their Stromberg WWC carburetors.

300G cross-ram wedge engine

Starting with the 1961 cars, Chrysler dropped the 361’s compression to 9:1 so they could run on regular gasoline; this caused a bit of a power drop, but by then performance-minded buyers were expected to use the 383. Because of this, 1962 was the final year for the 361 four-barrel in cars; the 361 left cars entirely at the end of 1966, replaced by the “LA” 360.

One other addition for 1961 was, for the moment, limited to California: a tube allowed crankcase vapors to be drawn into the carburetor, where they were burned, reducing smog. This closed crankcase ventilation system because standard on all cars afterwards, cutting emissions without any drawbacks other than another couple of parts.

Starting in 1963, Chrysler started working on a car that could win the Daytona race the following year. Tom Hoover and Don Moore decided to try adding hemispherical heads to the raised-block version of the B-engines, the RB. This would take the best of the B/RB series (a strong, modern block with wide cylinder centers) and the free-breathing, efficient hemi heads from Chrysler’s past performance engines, and merge them together. What they came up with for the 1964 Daytona was solely a racing engine, not street-legal; it achieved its goal and then some, with Chrysler vehicles taking first, second, third, and fourth place. NASCAR then insisted on Chrysler selling the engines in street-legal cars; the “Street Hemi” appeared in the 1966 Dodge and Plymouth cars as a result, taking the top end of performance. This will be dealt with in a separate story.

For 1965, Chrysler dropped compression on the 383 two-barrel to 9.2:1, again to allow the use of regular fuel; performance buyers were supposed to get the four-barrel.

Where is the number code? Check underneath the distributor. The first line shows the year (A=1965); then three numbers showing the displacement; then the month and day on the line below. HP means High Performance. On RB engines, the numbers are on a tag to the right of the distributor.

Road Runner 383

The next big news was the 1968 Plymouth Road Runner. The car was a real story in itself; to make it extra-special, yet affordable, Plymouth specified a new version of the inexpensive 383 engine rather than the hot 426 Hemi or even the big 440 RB V8. Outfitted specially for the Road Runner with the heads, cam, and manifolds from the 440, it produced no less than 335 horsepower and 425 pound-feet of torque with a single four-barrel carburetor. That was the Road Runner’s base engine; buyers could also specify a 440 (triple two-barrel carburetors) for 426 Hemi. After 1968, the hot 383 was available in other cars. (There was also a briefly made RB 383, more on this later.)

The world had moved on quite a bit since 1958; insurance companies had figured out how often claims were made on hot performing cars; especially those purchased by younger buyers (such as the Road Runner), and the U.S. government was dealing with the fallout of a highly mobile society which had few if any constraints on fuel economy or emissions. The Clean Air Act of 1963 had been amended in 1965 by the Motor Vehicle Air Pollution Act, authorizing national regulations on emissions starting with the 1968 cars (trucks were still largely ignored). As time went on, more amendments were made to cover more research and enforcement.

The first impact of these two issues was lower compression on the 383 in the 1970 cars, with a small drop in compression to 8.7:1; it fell again to 8.5:1 for the 1971 cars. For 1970, the two-barrel 383 was rated at 290 horsepower (4400 rpm) and 390 pound-feet of torque (2800 rpm), easily beating the hot four-barrel 340 V8; the four-barrel was rated at 330 hp and 425 pound-feet, on premium; and the 383 Magnum added just five horsepower to the total. The RB 440 engine, incidentally, turned in 375 horsepower and 480 pound-feet of torque, also running premium fuel.

Horsepower in the 1971 Road Runner, with the 383 four-barrel, was now 300, with 410 lb-ft of torque. But another change, adopting net horsepower, made the drop look far larger: 300 gross horsepower as just 250 net horsepower, and 410 gross torque was just 325 net torque. The average buyer, if they hadn’t seen the 1971 brochures, might have thought that the engines had really lost over 50 horsepower and 85 pound-feet of torque.

In 1972, to save time or money, Trenton Engine adopted a single bore size of 4.34 inches for all the B-engines, moving the 383 to 400 cubic inches. According to Rick Ehrenberg, writing in Mopar Action, they were originally going to standardize on a 4.32 inch bore for both the B and RB engines, which would make sense; but marketers didn’t want to stop at 396 cubic inches when they could so easily reach 400. There was more motivation: the new 360 cubic inch “LA” engine was fairly close to the 383.

In any case, the increase in cubic inches fought another drop in compression, yielding a net horsepower rating of 190 hp and 310 lb-ft with a two-barrel carburetor, and a healthy, 1971-383-beating 255 hp and 340 lb-ft with the four-barrel. It was still lower than the gross power ratings, but neatly beat the net ratings of 1971, even with the compression drop.

The 400’s credibility was not helped by a switch for the forged steel crankshaft to a ductile iron one, even if the new crank was durable. (This change required external balancing through a weight in the harmonic balancer.)

1977 400 V8

Electronic ignition came with some of the 1972 cars, and would quickly reach every car and truck; it was a major advance, providing more efficiency at little cost, while eliminating the need to set or replace ignition points.

Enthusiasts today can cheer a 1973 change: induction-hardened exhaust valve seats, letting B and RB engines from the 1973 model year onwards use unleaded gas without any problems. Induction hardening was a simple process of heating the seats to 1700°F, then letting them cool down. However, emissions rules were getting tougher year by year, and Chrysler engineers worked on avoiding the dreaded air pump adopted by GM and Ford to burn any hydrocarbons the engine didn’t already get to. Tuning engineer Pete Hagenbuch made repeated requests to add fuel injection, but it was deemed too expensive; instead, the Lean Burn system, the world’s first computer-controlled spark advance system, was created and installed on the B engines, and as often as not, removed shortly afterwards.

1977 lean burn 400

In 1975, the two-barrel 400 was producing 175 horsepower and 300 pound-feet of torque, which was close the the smaller and lighter 360; they were dropped entirely in 1976. For 1978, the 400 was given twin concentric throttle return springs in addition to the existing torsion-based spring; and every Chrysler engine gained an adapter so their techs could set the timing with the aid of a magnetic probe.

Finally, in August 1978, the last B or RB engine was made; that was Chrysler’s final big block. The last Chrysler truck using one of these massive engines left the line in 1979; but a large inventory allowed for their use in mobile homes for years afterwards. The company had made over three million 383 engines, along with numerous 361s and 400s.

Leave a Comment