After making its hemi V8s famous, Chrysler entered a new phase in 1958 with its wedge-head B Series V8.
While the Chrysler, DeSoto, and Dodge hemi V8s were a great engineering success for the Chrysler Corporation, they were less than optimum for the automaker’s bottom line. With their complex valvetrains and heavy construction the hemis were expensive to produce, and what’s more, the three V8s shared no major components. To streamline the products and operations, a centralized Engine Division was formed to create engines for corporate use across multiple brands. Its first project from scratch was the B V8 (internal code A561.)
The two initial production versions introduced in 1958 displaced a modest 350 cubic inches (4.03-in bore; 3.38-in stroke) or 361 cubic inches (4.125-in bore). However, ample room was included in the design for future growth: 4.800-in bore spacing and a 9.980-in deck height. The architecture was robust with the block casting skirted a full three inches below the crankshaft centerline and 17 cylinder head bolts per bank instead of the usual 10.
And trailing right behind the B V8 on the development path was the RB or Raised Block series (A652), virtually the same engine but with its deck height increased to 10.725-in to support even greater strokes and displacements. Within Chrysler the two sibling V8s were originally known as LB (Low Block) and RB (Raised Block), but eventually the B and RB labels stuck.
From the engineers’ perspective, the major departure in the B V8 was its wedge combustion chambers, which Chrysler termed “modified wedge.” Aligned with standard Motor City practice at the time, more or less, the wedge layout was not as efficient as the hemi, but it was lighter, more compact, and less expensive to produce. And in testing, with its generous quench and squish area it proved to be clearly superior to the polyspherical chamber, Chrysler’s first departure from the powerful but cumbersome hemi configuration.
With paired intake ports and extremely short exhaust runners, the cylinder head castings (interchangeable left to right) were engineered for light weight and low cost. Rocker arms were formed from flat steel sheet that was then blanked, coined, and heat-treated to precision tolerances, a significant savings over forged or cast components. However, Chrysler stayed with a tried-and-true rocker shaft for the mounting system. Hydraulic valve lifters were used from the start, with lubrication to the upper end through oil galleys to the rocker shafts.
In another departure from standard Chrysler V8 practice, the distributor was moved from the rear to the front of the engine (above) to get it away from firewall clutter and provide easy access. (Thus the B/RB might be the easiest of the early Chrysler V8s to identify.) The distributor, which shared its camshaft drive with the oil pump, was laid over on its side to enable a low hood height.
In his book Chrysler Engines 1922-1998, Chrysler engineer Willem L. Weertman reported that in early development, the oil pump gears would seize, snapping a pin in the drive. (The bible on Chrysler engines, we’ve relied heavily on it here.) But fortunately, since the distributor stopped turning at the same time, the engine simply stopped running, avoiding serious damage. After the usual bugs were worked out, the B/RB series V8s enjoyed a long and fruitful life, with the B V8 eventually growing to 400 cubic inches and the RB to 440 cubic inches, remaining in production through 1978 and also spawning the 426 Hemi V8.
For the 1958 launch, the B-series engines were offered in multiple states of tune, including high performance versions: a Golden Commando V8 for the Plymouth Fury with 350 CID and 305 hp, several 361 CID Dodge D-500 V8s with up to 320 hp, and the 361 CID DeSoto Adventurer with 345 hp. However, there was one ambitious B V8 initiative in 1958 that didn’t make it. A handful of Plymouths, Dodges, and DeSotos were equipped with Bendix Electrojector fuel injection (below). The Bendix system wasn’t ready for consumer use and was quickly withdrawn from the market. The Motor City’s earliest attempt at electronic fuel injection was a failure, and you can learn more about it here.
Very informative article!
Thanks, Frank
>> the hemis were expensive to produce, and what’s more, the three V8s shared no major components.
I wasn’t aware that there were few shared parts. That seems like a serious miscalculation but I don’t know that much about engines prior to 1955. I would guess that a unique engine was part of what made a marque’s identity. You moved up from a Pontiac to an Oldsmobile in part because the Olds had a Rocket V8. And when you found out your Olds had a Chevrolet engine, that was cause for a lawsuit. There was a time when brandmates had more differences than the grille & taillights.
There’s a theory in manufacturing, related to diminishing marginal returns of scale, that once you reach a certain volume level, greater production volume does not result in a significant reduction in unit cost. So here, it can be justified for each car division to have it own engine, for example. Fair enough, but among other things, it doesn’t fully take into account product research & development, which is really the cost of ideas. For example, here people needed to think up and create three different engines rather than one, and what does an idea cost? The theory doesn’t really include logistics, either. Imagine a Chrysler parts buying, receiving, and distribution system with parts for three different engines rather than one. -mcg
Great writing, the 1958 Chrysler big block V8 engine is indeed an engineering masterpiece, the coined rockers certainly are for sure!
Walter P. Chrysler absolutely loathed William “Billy” Durant’s GM management style of chaos, but spent his life copying Durant’s exact multi-brand strategy to build Chrysler Corporation. The personal and professional warfare between Mr. Chrysler and Durant is one of the greatest rivalries in automotive history. By the 1950s, this resulted in the engineering bloat where Dodge, DeSoto, and Chrysler were spending millions to build completely different, non-interchangeable Hemi V8 engines rather than sharing one corporate design.
The ultimate paradox of Chrysler’s corporate engine culture: while they may have let GM-style divisional turf wars fracture HEMI V8 development, Mother Mopar ruthlessly used the same 6-cylinder flathead engine from 1932 across every single brand until 1959, except Imperial of course…
Kevin Voegel back in 74 purchased a 55 Desoto had a 291 Hemi put in a 49 pickup with a tilt doghouse. But in 78 purchased a 59. 354 Hemi came out of a Chrysler put it in the same 49.pickup. In 2013 purchased a 56 Chrysler Imperial it had a 331 Hemi. I rebuilt, had powder coted