Willys Overland Jeepster

Information Site and Registry 1948, 1949,1950

Detailed engine history

Willys Jeepsters came with standard 134 cubic inch 4 cylinder engines, or (starting 1949) 148 cubic inch 6 cylinder engines; the 6-148 was eventually enlarged to 161cubic inches by increasing the piston diameter from 3 to 3-1/8 inches.  The 4-134 was originally a flathead (side valve) and, after about 1950, an F-head (side exhaust and overhead intake valves) version was introduced.  When the new 1952 Willys Aero was introduced, an F-head version of the 6-161 also became available.  Jeepster production ended in 1950, before the F-head 6-161 was developed.  F-head configurations had some advantages of overhead valves without the time needed to develop or tool up for new engine designs.


After 1953, a 226 cubic inch flathead 6 became optional in Willys cars, station wagons and trucks.  It was not originally a Willys product or design, but was made in the Willys Toledo works.  It might seem logical that a 6-226 will readily swap into a Jeepster, but it is not easily done.  The 6-226 was originally a Continental engine used in Graham cars before World War II.  In February, 1947, Graham-Paige Corporation’s automotive assets were acquired by the new Kaiser-Frazer Corporation, and the 6-226 went into full-size K-F cars.  The cars were produced at a former wartime aircraft factory at Willow Run (near Ypsilanti) Michigan.  K-F initially bought engines from Continental, but in 1947 leased part of Continental’s old East Jefferson Avenue engine factory in Detroit (just down the street from big Hudson and Chrysler plants) and made 6-226 engines with its own employees, paying  Continental royalties.  During peak demand, K-F obtained additional 6-226 engines from Continental’s main plant in Muskegon.  In 1951, K-F bought the former Continental Detroit engine factory outright, with the right to make future 6-226 engines royalty-free. 


K-F’s 6-226 engine castings were made in an iron foundry in Dowagiac, Michigan (north of South Bend, Indiana), which formerly made Round Oak brand iron stoves.  K-F bought it in 1947.   (Today the Dowagiac foundry buildings are used by Ameriwood Corporation to manufacture wood products.)  Not all engine castings for 6-226 engines came from the Dowagiac foundry.  Some engines were cast by the  Lakey Foundry, whose casting mark is a flattened “C” superimposed over an “L” like a draftsman’s “centerline” symbol, and some came from the Campbell, Wyant & Cannon Foundry, casting mark “CWC.”  (CWC is now owned by Textron, and its largest customer is Toyota.)


The 6-226 can be identified by a distributor that stands straight up on its cylinder head, between the fourth and fifth cylinders.  Manifolds, carburetor and side valve covers are on the right (curb) side, while starter, generator, oil filter, oil filler tube and dipstick are on the left (driver’s) side.  By contrast, the Jeepster flathead 6-148/161 had its starter, generator, oil filler tube and distributor on the right side, and its manifolds, side valve covers and carburetor on the left, essentially the reverse of the 6-226. 


Casting marks on the 4-134 and 6-148/161 were usually “WF,” which stood for the Wilson Foundry of Pontiac, Michigan.  Wilson Foundry was owned by Willys-Overland, and also made castings for GM’s Pontiac engines.  Sometimes the single letter “W” is followed by a single-digit number, such as “W1” or “W4” instead of “WF.”


Today some Jeepsters (including mine) have F-head 6-161 engines that were swapped into them.  It’s a relatively easy swap, even in place of a 4-134.  Radiator (minus shroud), starter, generator, flywheel, clutch, transmission, and exhaust system (except for the front pipe) from a Jeepster 4-134 will work with a 6-161.  On the other hand, I’ve only seen one Jeepster with a flathead 6-226 swapped into it.  Although the job was skillfully done, it was a difficult swap.  The 6-226 is too long for Jeepsters between radiator and firewall.  The bell housing is also longer, and its bolt pattern is different.  A Jeepster bell housing won’t work with a 6-226, nor a stock Jeepster transmission, clutch, linkages, starter, etc.


Here are some approximate lengthwise dimensions of the 4-134, 6-148/161, and 6-226 engines.  I have included approximate dimensions for the Kaiser Jeep/Buick V-6-225 and the Chevrolet small-block V-8-283 for comparison.  These are ranked in numerical order, shortest to longest:


Engine Type Block (bare)      WP          BH    Block+WP+BH Rank, 1=shortest to 5=longest

4-134       19-1/4”           4-1/2”            7”    30-3/4”           2

6-148/161   24”         5”          7”    36”         4

6-226       25-1/2”           5-1/4”            10”   40-3/4”           5 (Longest)

V-6-225           17”         7”          6”    30”         1 (Shortest)

V-8-283           20”         6-1/2”            6”    32-1/2”           3                

“WP” = water pump (without fan); “BH” = bell housing (without transmission).


For further comparison, modern GM inline 6-cylinder engines in Chevy Trail Blazers and GMC Envoys are approximately 32” from the front of the water pump to the rear of the engine block.  A 6-226 is 30-3/4” long in that dimension – not especially long, but a 6-148/161 is especially short for an inline 6 (only 29” in that dimension).  Corporate history helps show why the 6-226 was not factory-installed in Willys vehicles until after the Kaiser acquisition in 1953. 


During Willys-Overland’s 1933-36 bankruptcy, the company’s 6-cylinder production equipment and its flathead 6-cylinder engine design were sold to International Harvester.  (IH was still making it for its light trucks after the war.)  W-O’s remaining engine was its flathead 4-134, an evolution of the 1926 Overland Whippet 4, made in Toledo on old Whippet engine production equipment.  Capacity was only 300-400 engines daily.


The Willys 6-148 engine was newly developed after the war for a new low-price car to be called the Willys 6/70.  The new car would have had conventional styling, seating for 5 passengers, and 4-wheel independent suspension.  The new 6-148 engine was essentially a smaller scale, longer, less-tall version of the 4-134.  It was smooth and quiet compared to the 4, but only slightly more powerful, and about the same weight.  It was ready for customers by 1947, but W-O still lacked new equipment to efficiently mass-produce it.  By one account, production of early 6-148 engines was contracted out to former Hupmobile manufacturer Hupp Corporation; others say Continental produced them.


By the time other U.S. car companies rolled out their newly-styled postwar models in 1947-48, the 6/70 car had been permanently shelved.  The new Willys station wagon had been introduced in mid-year 1946.  The first 6-148 engines went into the high-end station wagon models.  Jeepsters were unveiled in mid-year 1948, initially with flathead 4-134 engines only.  Station wagon sales were good, but not Jeepster sales.


  Since emerging from bankruptcy in 1936, W-O’s majority shareholder was Ward Canaday, Harvard class of 1907.  Canaday was not a car guy.  He treated W-O as an investment.  Three different company presidents came and went between 1939 and 1949.  Each was an experienced, well-respected automotive executive, and none met Canaday’s profit expectations. 

After January 1949 Canaday took over as company president himself.  By then he was in his mid 60’s, and looked forward to pursuing his interest in Greek antiquity.  Sales fell in 1949, and by January 1950 Canaday was confidentially exploring an exit strategy.  He consulted industrial broker Samuel Vance, but instructed that no one be told his desire to dispose of his W-O interest, or his price.


Also In January 1950, Canaday successfully negotiated with Edgar Kaiser (son of Henry J. Kaiser) to supply Willys flathead 4-134 and 6-161 engines for K-F’s new “Henry J” small car, and mentioned to Kaiser that K-F and W-O should merge.  Canaday asked for a firm commitment.  Kaiser backed off. 


With Jeepster sales not improving, no long-range plans and no new models in development, Canaday suddenly decided in early 1950 that it was time to produce an all-new car, and to do so as quickly as possible.  Former Packard engineer Clyde Paton had been visiting car companies (including W-O) trying to interest them in his proposed new light car.  Canaday now told Paton to go forward with his new design, with time of the essence.


 Meanwhile Canaday’s broker Vance associated himself with another broker, Millar Brainard, who arranged a meeting between Canaday and Cyrus Eaton, an investor who was at odds with the Kaisers over performance of his Kaiser-Frazer investment.  Those talks went nowhere. 


By 1951 prototypes of Paton’s new car, dubbed the Willys Aero, were ready.  Canaday invited Edgar Kaiser to Toledo to show them off.  If Canaday hoped the new car would motivate Kaiser to make a generous offer, he was disappointed.  Kaiser didn’t like the new Aero, and doubted that enough could be sold to turn a profit.


But K-F had its own problems.  It had sought government financial assistance after over-producing, and agreed to limit future monthly car production to not more than 50% of its October, 1950 production, and to give first priority to defense production.  Government-owned defense-production equipment was installed at Willow Run and Dowagiac.  An inactive Kaiser-owned corporation, the Phoenix Iron Works (chartered in Pennsylvania), was activated and re-named Kaiser Manufacturing Corporation to handle government work.


In 1952, with both military aircraft and K-F cars being produced at Willow Run, K-F informally participated in merger talks with Consolidated Vultee Aircraft Corporation (Convair) and Atlas Corporation, a major Convair stockholder.  Atlas’ representative was David Baird, who was also a large Willys-Overland shareholder.  Baird floated the idea of a three-way merger of Kaiser-Frazer, Atlas (Convair) and Willys-Overland, with Canaday selling his interest as part of the deal.  When Canaday heard about it he objected, and talks collapsed.


The new Aero had a unitized body that was beyond the capabilities of Willys’ body-making equipment, so Murray Corporation made them.  In January 1953, Canaday and Edgar Kaiser met to discuss possible joint production of car bodies.  Kaiser sensed that Canaday, now in his late 60’s, had changed his tune, and now wanted to get out of the car business sooner rather than later.  The station wagon had been on the market for 6-1/2 years without significant updating, and W-O had no new models in development.  The Aero was not selling in profitable numbers, and Canaday was ready to throw in the towel. 

 In March 1953, an agreement was reached that Kaiser Manufacturing Corporation would be re-named Willys Motors, Inc. (still chartered in Pennsylvania) and take over W-O’s manufacturing assets and trademarks.  Willys-Overland Motors, Inc., a Delaware corporation, would continue as a corporation headed by Canaday, and would be re-named Overland Corporation, but without the right to use the name “Overland” as an automotive trademark.  The deal closed in April, 1953, and some months later, Kaiser-Frazer Corporation was re-named Kaiser Motors Corporation. 


One of the first steps to consolidate vehicle production was to modify the engine compartments and related parts of Willys cars, station wagons and trucks to allow installation of the K-F 6-226 engine.  That helps explain why a 6-226 engine is hard to swap into a Jeepster, which has a smaller engine compartment and transmission hump than outwardly-similar station wagons.  Some minor internal changes were also made to the 6-226 engine, such as replacing the barrel-shaped valve lifters (tappets) with mushroom-shaped ones similar to those used in Willys 4-134 and 6-148/161 engines, and casting the name “Willys Super-Hurricane” into the head instead of “Kaiser Supersonic.”  Intake manifolds and carburetors were eventually changed to use manual chokes, like other Willys engines.


In mid-1953, the Korean conflict was winding down, causing cutbacks in defense work.  Coincidentally, GM’s huge Hydra-Matic transmission plant in Livonia, Michigan burned down in August, 1953, the largest industrial fire in U.S. history.  GM quickly leased space at the huge, underutilized Willow Run factory and began installing new production equipment for Hydra-Matic transmissions.  GM soon bought the huge plant outright, giving Kaiser time to remove its remaining car production equipment and ship it to Toledo.  Kaiser’s Dowagiac foundry produced Hydra-Matic transmission parts during GM’s emergency, and then it was closed and sold.  The old Continental Detroit engine factory was also closed down and sold, with engine production equipment shipped to Toledo and Cordoba, Argentina, where Industrias Kaiser Argentina in Cordoba produced a South American version of the 6-226.  Production of Kaiser cars based on the 1955 model eventually resumed in Argentina, and continued into the 1960’s, eventually with facelifted styling.


 By 1955 the 6-161 engine had been discontinued in U.S. models, replaced by the less efficient but more powerful 6-226.  Production equipment for the F-head version of the 6-161 was shipped to Willys-Overland do Brasil in Sao Paulo, where it became the first gasoline automotive engine produced in Brazil.  Tooling for the 1955 Willys car was sent to Brazil after U.S. production ended, and that car, eventually with facelifted styling, was produced in Brazil with the F-head 6-161, being re-named the Ford Aero after Ford acquired the Brazilian company in 1967.  Brazilian F-head 6-161 engines were eventually improved with stud-mounted stamped rockers, full-floating piston pins with solid drilled rods, improved exhaust valves and manifolds, and sometimes dual carburetors mounted on a water-heated intake manifold.  (Normally F-head Willys engines had their carburetors bolted directly to the head, without separate intake manifolds.)  In its highest-performance version, the block was modified and the piston stroke was lengthened from 3-1/2 to 4 inches, producing 140 horsepower, same as the early-1960’s Toledo version of the 6-230 overhead-cam Jeep “Tornado” engine.  It became the standard engine for Brazil-made Ford Mavericks until the late 1970’s.


In the 1960’s, both the Toledo and Cordoba factories made the overhead cam Jeep “Tornado” 6-230, which was an evolution of the 6-226 engine, using the same crankshaft as the flathead 6-226, but with surface-hardened journals.  Plans called for the “Tornado” to be the basis for a new overhead-cam 4 that would replace the F-head 4-134.  Plans changed, and the “Tornado” was withdrawn from U.S. civilian models in 1965, replaced by a newly-designed AMC 6-cylinder engine from a new jointly-owned AMC-Kaiser engine factory in Mexico.  The F-head 4-134 was supplanted by 225 cubic inch V-6 engines initially purchased from Buick.  When GM stopped making the Buick V-6, its engine production equipment was sold to Kaiser Jeep (as Willys was then known) and shipped from Flint to Toledo, where production continued until a few years after AMC acquired the company.


In Toledo, “Tornado” engines were produced for Kaiser military trucks until the late 1960’s, then discontinued.  But in Cordoba, the “Tornado” was improved and upgraded into a more-modern high-performance engine with a seven-main-bearing crankshaft.  That cured the unfortunate problem of 1930’s-designed 6-226 four-main-bearing crankshafts flexing and snapping at high engine revs.   The “Tornado” became the standard engine for Argentina-produced Ramblers into the 1970’s.  The Argentina factory also produced the Toledo-planned 4-cylinder overhead-cam variant for Argentina-made small jeeps.


Continental also made its own 6-226 engines into the 1960’s, including a conventional overhead-valve (not overhead cam) version.  Most went to Checker Motors in Kalamazoo, the taxi specialist.  Continental-produced 6-226 engines also went into industrial generators, air compressors, forklifts and the like.  Graymarine converted them into boat engines.

Information provoded by Morris Hill