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Origins of Ford Aero and Tank Engines, the American Merlin, and the writings of Maurice Olley.

 Before the entry of the United States in the Second World War, the U.S. had become a supplier of war materials to those countries with similar governmental outlooks. Our then President, Franklin Roosevelt proclaimed that the U.S. was “The Arsenal of Democracy”. 

One of our major customers was Great Britain, who, for a number of reasons, decided to have their very successful Rolls Royce Merlin aircraft engine manufactured in the U.S. The usual explanations of the advent of the American Merlin are:

 1. In 1940, through the efforts of Edsel Ford, President of Ford Motor Company, an agreement was made for Ford to build the Rolls Royce Merlin Engine at one of Ford’s depression idled factories.

 2. Two Merlins were built in the Ford Prototype shop, that, were “less than acceptable”.

 3. Henry Ford, Edsel’s Father, founder of “Ford” and Chairman of Ford’s Board, rejected the Merlin Contract on the basis that 60% of the Merlin’s were to go to British “uses”. Henry was not a fan of the British and stated that Ford would only manufacture for U.S. Defense. British “uses”, were mostly to be used in U.S. built export aircraft and in Canadian built Airplanes from British owned “shadow” factories. 

 4. Supposedly Bill Knudsen, President of GM, former V.P. of Ford, who President Roosevelt put in charge War procurement, went to see Henry to ask him to reconsider, and was told to leave Ford’s Office.

 5. Merlin production was then moved to Packard who successfully built over 58,000 Merlin’s, over ½ of which ended up in U.S. Army Aircraft, including later marks of the famous P51 Mustang Fighter.

 6. Some have gone as far to say that Ford did not have the ability to build the Merlin.

 7. Ford Continued to develop their Aero Engine on their own, which was very different from the Merlin and incorporated many of Ford’s proprietary construction processes.

 8. The U.S. Army approached Ford to adapt their engine to replace the previous inadequate engines used in the Sherman Tank. Ford shortened the engine to fit the Sherman by removing 4 cylinders to make a V8 and then built over 28,000 and of the lesser tuned GAA and variant GAF and GAN V8 Tank engines. Toward the end of the war two production runs were made, likely totaling about 50 engines, of the GAC V12 engine for the prototype T29 Heavy Tank and other derivatives thereof  .  

 Writings of Maurice Olley

 Maurice Olley spent his career alternating between both sides of the Atlantic.  His specialty was automotive chassis design, his principle employers were Rolls Royce Limited and General Motors. During the First and Second World Wars he also worked for various British firms and agencies on procuring materials for the British War efforts.

 The following excerpts were taken verbatim, including his punctuation from his book:

 **Chassis Design, Principles and Analysis.**

 From his Chronology:

 1939: In August to N.Y. and Detroit for regular summer visit. WWII starts, all American passports cancelled. In Detroit, promote concentrated drive to save body weight on passenger cars both by design and by control of metal thickness to closer tolerances. Also through physical testing of body stiffness. The program is adopted, but I don’t get it. Hives {RR Ltd.} discovers me in Detroit, and on receipt of his cable I beg off the GM program and receive “leave of absence.”

 October 1939. Work for Rolls-Royce in Detroit complicated by lack of funds, and by fact under Michigan law, if I do business in Detroit for Rolls-Royce I become a “foreign agent”. American enthusiasm to “stay out of the war” makes this dangerous. McManus {British Representative} incorporates a Michigan company as a legal safeguard.

 Acquire m/s tools [probably special purpose machine tools, which the U.S. were superior manufacturers] and small tools, and ship to Rolls-Royce Ltd. Assisted by British staffs in N.Y. and Washington.

 Try to persuade Packard to manufacture sub-assembles for Merlin engine, on the same principle as used in WWI. They won’t do this without contracting for complete engines, and no one will find the money for this.

 Get Wyman Gordon in Chicago making Merlin crankshaft forgings, including special steel for Republic Steel Co. Get Bower Roller Bearing Co. to work on Merlin Bearings.

 June 1940. [the Battle of Britain, Merlin’s so important] The famous shipment of Rolls-Royce print records. Purloined by U.S. Treasury Dept., handed to U.S. Air Force and landed under guard at Wright Field, with three cornered fight between U.S. Customs, Treasury and Air Force. Washington decides Ford shall make the Merlin in the U.S.A.

 Nearly a week spent in Dayton, Ohio, awaiting release of Rolls-Royce prints (hot weather, Paris falling and tangle of red tope getting thicker by the minute).

 Release of prints refused and we returned to Detroit. Arrive at Ford to learn that Merlin prints only are released. Drive back to Wright Field, recover prints and return to Ford at 3a.m. Performance of Ford people defies description. Merlin prints are like autumn leaves, being duplicated, retraced, microfilmed. Within two weeks Merlin Crankshafts are in existence, in correct material but cast instead of forged. A engine design appears and is built in extremely short time and on dynamometer. It is dimensionally the Merlin, but built without a single Merlin detail. With fuel injection, cast crank, aluminum block with dry sleeves, etc. [Eight cylinders of it, with carburetor, later become Ford tank engine.] Meanwhile negotiations between Ford and Washington reach complete stalemate, and instructions come from Washington to transfer all Merlin prints to Packard. Ford opposes this, claiming they will make the engine. Finally prints are retrieved and brought to Packard, who take their time, use their heads, and eventually, with assistance of engineers from Derby, do an excellent job. 

 From Maurice Olley’s Reminiscences 1-1:

 There were 6 months of “phony war”. During this time I bought small tools and machine tools for RRLtd, out of my own pocket till finally the British Treasury saved me from bankruptcy. I had to incorporate myself to avoid becoming a “foreign agent.” I had to contend with the Zeiss people in New York who were buying up all Ziess instruments to prevent the allies getting any of them. For months I felt like an international spy. 

 The phony war came to a sudden end, and RRLtd, to preserve their records, filled an engine case with prints of all their drawings and sent them to Halifax, N.S. consigned to me. Previously I had only a few prints of the Merlin Engine, obtained from the Cincinnati Milling M/c Co, and from these had been trying to persuade various American manufacturers to undertake parts-production. Now the scene was changing and there was discussion of manufacturing the complete engine in the U.S.A. On the strength of these discussions the U.S. Treasury Dept. seized the case of drawings in Halifax and held it “somewhere in Washington” under Military guard, thus stalling all constructive action for several weeks. During this period, Paris was entered by the Germans and France had collapsed. England was to stand alone for the next six months facing Hitler with all Western Europe behind him. Under these circumstances the delay appeared disastrous. 

After a period of purgatory however it was decided that Ford would build the Merlin engine. All my activities were transferred to Dearborn for the next two months, The Merlin drawings has mysteriously appeared at Dayton, and were released and transferred to “Gate 4”. (The remainder of  RRLtd’s drawings were not released until months later)

At the end of two months, everything was in the air again, Ford had refused the Merlin contract and it was transferred to Packard, my office was moved back to the GM Bldg. and we started over again. Luckily Packard were well acquainted with the engine having been approached as early as October 1939 to make parts, notably crankshafts.

Followed a period during which Packard got started on redrawing all engine details, extending the plant for new engine testcells finishing contract negotiations, an deciding some of the vital details of any contract, such as “ Are American threads to be used, What ignition system, carburation, system, bearing materials, etc. are to be used?” Three RRLtd. Engineers arrived with their families and took over the job, and I could get back to my parts supply business, which had now almost standardized itself.


 Jim’s Responses.

 Olley’s writings appear to somewhat challenge the usual explanations concerning Ford and appear contradictory;                                                                                           

 “Ford opposes this, claiming they will make the engine”.{Timeline},

 “Ford had refused the Merlin contract and it was transferred to Packard”. {Reminiscences}

 To me, both are correct, Ford wanted to build “the” engine, their engine, they did want to build the Merlin as designed by RR Ltd. The two “less than acceptable” engines were without a doubt the Ford design, not Ford built Merlin’s. 

 Simply Ford engineers did not like the Merlin design, they thought it to be overly involved and complicated. They had made a very successful corporate model of simplicity and durability. At that time they were producing the highest performing, low cost automobile in the world, they saw no reason they could not do the same with Aircraft Engines.

 The Merlin contract would have given Ford the entry into the market, which is why it was pursued.  It is obvious from Olley’s writings that RR Ltd. did not approve of Ford’s version of RR’s design. However, from what I read here, Olley has a grudging respect for Ford, as to their amazing ability to design and build an engine that quickly. One wonders if Ford had a preliminary design for their engine before entering in the Merlin negotiations.

 The idea that Ford did not have the ability to build the Merlin, as designed by RR Ltd. is ridiculous. This opinion is proved that to be specious by their British Factory which, starting in 1941, made over 30, 000 Merlin’s without one reject! Like Packard, the British Ford factory redrew the RR drawings and tightened the tolerances so the engines could be mass produced. If they could do this in England, they certainly could have at their main plant in Dearborn, they chose not to. The Ford GG aircraft V12 showed great potential, producing over 1800 Hp on its initial dyno test!

Would the Ford Aero Engine been a good Aircraft Engine?

 My opinion is, absolutely.

 A. Through the efforts of their designer, Charles Sorrenson, aka “Cast Iron Charlie”, Ford was the first carmaker to mass produce  “enbloc” V engines, namely the Ford “Flathead” V8’s and the Lincoln V12’s. The aluminum 1650 C.I. enbloc V12 Aero engine was well within their capability. It was far more rigid than the multi piece Merlin or the GM Allison blocks and could have been pushed far harder and been capable of more horse power.

 B. The cast crankshaft as mentioned by Olley was made with a process pioneered by Ford and used very successfully in their cars and trucks. As the load on the crankshaft is far more uniform in an aircraft engine than that of a land vehicle, it would not likely have caused problems. Vigorously engaging the clutch of a car results in approximately 10 times the transitory load than an aircraft crankshaft of similar horsepower will ever experience. A few of the early Tank engines had some crankshaft problems as these models maintained the thinner block casting and the “lace” main caps of the prototype Aero engine. Sometimes, the tank-driver would “drop the clutch” causing the original main caps to slightly deflect and the crankshaft to move longitudinally. This was totally cured in later engines with the use of more conventional 2 very large stud main caps and by reinforcing the main bearing webs.  In an aircraft engine, this would have never been a problem. Further the Ford crankshaft had bigger journals and therefore was more rigid than the Merlin. Had the Aircraft engine been accepted for production, perhaps the crankshaft may have been changed to a forged unit; however, all in all, the cast units worked very well in the Tanks and in extreme postwar performance uses.  

 C. The Ford’s used “standard” side by side rods, which resulted in far lower construction costs, higher strength, and less weight than the Fork/Blade rod system as used by Rolls Royce, Allison and other Aircraft engines. Again Ford had considerable experience with this type of arrangement and knew its reliability and strength. Like those in their automotive V engines, they used “floating” rod bearings with bearing surfaces on both the inside and out, for longer life and less friction. The only possible negative to the Ford side-by rod design was that the overall engine would have been about 1.25 inches longer.

 D. The valve train was again superior with dual overhead cams (4 total) V/S the single OHC of the Merlin. The drive to the cams was also superior, as was the use of cam “bucket” followers which directly drove the valves without any possible follower flex.

 E. The combustion chamber of the Ford engine was a “Pent Roof” design with four large valves per cylinder and spark plugs located in the center of the chamber for less flame travel than the Merlin.

 F. The Bosch direct fuel injection of the Ford was superior to the carburetion of the Merlin, as proved by the Germans in their aircraft of the time. I wasn’t until much later, about 1944, that the Allies started to quite successfully test this method.

 G. The Ford designed dual stage Turbocharger showed great promise, however, was not completely developed and had the “contract” been allowed to continue, may have been replaced by the superb Hooker Supercharger of the Merlin. As it was, the Ford Turbocharger showed inspiration from the Hooker Supercharger.


 In this person’s opinion, the Ford Aero Engine, had it been allowed to develop, would have been a superior engine to the Rolls Royce Merlin. However, at the time, we needed good Aircraft engines, immediately, the Merlin was a known quantity. The de-rated Ford Tank engines, with their less than optimum carburetion arrangement, were very successful and continued to be used in Foreign Service into the 1980s. Properly modified V8 Tank engines are still being used in very high performing Truck and Tractor Pullers.

 If things had been different, we may have had Ford powered Mustangs by 1943, and I do not mean, cars.

 Jim Dickinson                                                                                                  

Copyright, 2013-2014    


I personally own two of the Ford GAF 1100 cubic inch Pershing Tank Engines, the last variation of the V8 tank engines. I got one running last year, the first time since its military rebuild in 1954. The other, also rebuilt at the time has some rust damage in the bores and needs to be bored out on about four cylinders. The running engine has the same "big" sound of the WWII V12 aircraft engines, but with a different cadence. Due to the 60 degree V angle and the "flat" crank shaft it does not sound like a normal V8, more like the sound of a Griffon.There are likely about 500-1000 V8 GA series Tank engines remaining in the world, in various states of repair.

 I know of only the confirmed existence of four remaining 1650 C.I. G series V12 Fords,  they all appear to be GAC Tank V12's. Two are in preserved T29 prototype Tanks in the Army Armour Museum, one is loose somewhere in California, I have not been able to find it, and another is in the Ford Museum archives in Dearborn Michigan. The one in the Ford Museum may be the only prototype Tank engine with fuel injection, as that was done after the war's end.  There are rumors of about another 15 or so out there, mostly outdoors in greatly deteriorated condition. The two GG Aircraft engines and the two prototype supercharged PT boat engines appear to no longer exist.  If you know of the whereabouts of any of the V12's, please let me know.

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Comment by ED Hollowell on November 1, 2020 at 9:14am

I first became aware of Ford's involvement in the production of the Merlin from the book "The Fords, An American Epic" By Peter Collier and David Horowitz. In that book the reason for Ford not building the Merlin was made plain. Henry threw a fit about producing war material for the British. Henry canceled the contract that Edsel had already signed to produce the engine.

I took this as fact for some time.

I later read "Allied Aircraft Piston Engines of World War II" by Graham White and felt that he must have got the wrong story as he said that, after Henry Ford rejected the contract he set out to build his own engine. I had never heard about this.

I then was studying up on tanks and heard the Ford GAA engine described as the 'development of a aircraft engine Ford had designed but never produced'. My curiosity was peaked and I did a search for more on the GAA and that lead me to this post and Maurice Olley. Thank You for posting the explanation of why Ford backed out of the Merlin contract. It now seems to me that the 'The Fords' book version of the story was just a way to present an entertaining narrative about the decline of Henry Ford rather than truth. It's disappointing when "History" turns out to be nothing more than a promotion of the author's imagination. They thought Henry had lost his mind and built a story around it.

At this point I have to believe that Ford felt they had built a better engine and they could corner the customer into excepting it as a substitute for the Rolls-Royce Merlin.

It's also a surprise I had to read about tanks and boats to arrive at this point!

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