It's rarely mentioned as a performance pioneer, but the 1957 Oldsmobile 371 J-2 Golden Rocket engine deserves more respect, even if it's more than 50 years since it was installed in a few thousand Super 88s.
The Olds V-8 was an overhead-valve (OHV) design that was very similar to the Cadillac and Chevy V-8s; the Cadillac OHV was introduced in 1949, the same year as the Olds V-8, and the Chevy, of course, in 1955. In fact, the Chevy and Olds blocks look surprising alike, although the Oldsmobile has a larger, more prominent bell housing and a more enclosed valley. The Chevy had the edge on cylinder-head airflow, but the Olds made up for it with cubic inches.
By 1957, the Chevy mill increased from 265 to 283 cubic inches, but the Olds engine was nearly 90 cubes larger. And, of course, one of the axioms of engine performance is there's no replacement for displacement. With its J-2 triple-carb induction system, the 371 was rated at 300 horsepower and 400 lb-ft of torque, 17 horses more than the much-celebrated-yet-finicky 283 horse, fuel-injected Chevy 283 engine.
The big-inch Olds topped the output of the non-Hemi Mopar 318 engine (290 hp) and Ford's 312 (245 hp). The supercharged Thunderbird engine was rated at 300 hp, but the Olds was naturally aspirated. And when it came to its GM-engine cousins, the J-2 engine equaled the output of Buick's top 364cid Nailhead engine and bested Pontiac's top 347-inch, Tri-Power engine (290 hp). It was also comparable to Cadillac's 300 and 325hp engines.
Indeed, the triple-carb J-2 engine was a stout performer on paper, but they're relatively rare finds today. That's because the tri-carb setup quickly gained a reputation for less-than-reliable performance and wasn't very popular. Frequent tuning was a must for optimal, stumble-free performance.
The vintage Olds V-8 is a...
The vintage Olds V-8 is a product of GM's development of overhead-valve eight cylinders after World War II. It was introduced in 1949 and carried the basic configuration that is used on modern V-8s 60 years later.
The biggest performance problem was the non-progressive nature of the induction system. As was typical of 3x2 systems at the time, the center Rochester two-barrel was the primary carburetor and the front and rear carbs kicked in simultaneously; they were either open or closed. However, there wasn't a mechanical linkage between the center and outer carbs. The vacuum-actuated front and rear units opened when the throttle on that center carb reached about 60 percent of wide-open. Power application was smooth enough, but lack of a direct link between the center and outer carbs created tuning issues. Also, the outer carbs tended to load up or become clogged without frequent use.
Tuning issues, a low "take" rate by customers and a comparatively expensive per-unit cost doomed the J-2 after the 1958 model year. It was a production run of only two years, although stacks of leftover intakes were reused and distributed to dealers with the front and rear carb mounts capped and a single two-barrel used in the center position. It was a solution for customers who were fed up with triple-carb headaches.
A modern J-2
Despite the J-2's relative unpopularity when new, it has the aura of exoticness today and exemplifies a bygone era, much like Googie architecture. Factory multiple-carb setups have always been rare and the J-2 was unique in Olds' lineup.
John Denyer has always been a fan of Oldsmobiles and J-2 engines. When he located a 1957 Golden Rocket, he thought it would make a great powerplant for his 1949 Olds. But like any self-respecting hot rodder, we wanted more from his J-2 than the factory supplied. He also wanted the cruising assurance of trouble-free reliability and rotating-assembly durability. For that, he turned to Wixom, Michigan's Thomson Automotive, a longtime street- and racing-engine builder.
Denyer's plan was to have the engine retain its original look, especially the tri-carb induction system, but carry stronger, reliability-ensuring parts on the inside. To that end, the engine work included:
* A slight increase in displacement
* Adoption of Chevy big-block connecting rods
* Modern forged aluminum pistons
* Custom-grind camshaft
* Oil filter system changed to accept conventional spin-on filter
One of the distinguishing...
One of the distinguishing features of the Olds engine is the extra-wide bell housing that was required to cover the early Hydra-Matic automatic transmissions. The 568929 casting number on the bell housing identifies this as a block for a 371 engine.
The project engine's block...
The project engine's block was cleaned and prepped for assembly at Thomson Automotive. The bores were stretched slightly, from 4.000 inches to 4.093 inches. They'll be matched with a longer stroke to give the engine approximately 20 additional cubic inches.
Suitable Oldsmobile bearings...
Suitable Oldsmobile bearings were difficult to locate, so Thomson Automotive used Chevy bearings. Part of procedure involved carefully splitting the rearmost bearing in order to provide unrestricted flow from the block's oil hole.