Model A's





Engine Color: Green

Ignition Point Gap: .016" - .020"

Spark Plug Gap: .035"

Spark Manual Advance: 20

Rotor Dist. Terminal: .025"

Condenser Capacity: .20 to .25 MFD

Rotor Rotation: Counterclockwise

Spark Plugs: Champion 3X, 7/8-18 Thread

Oil Capacity: 5 quarts

Firing Order: 1-2-4-3

Rated Horsepower: 24.03 SAE

Brake Horsepower: 40 HP

Compression Ratio: 4.22:1

Piston Displacement: 200.5

Bore: 3.876"

Stroke: 4.250"


Model A Engine Specifications

..The engine was an L-head 4-cylinder with a displacement of 3.3 L. This engine gave the car 40 horsepower (30 kW). Typical fuel consumption was between 25 and 30 mpg (U.S.) (8 to 12 kilometers per liter or 12-8 L/100 km) using a Zenith one-barrel up-draft carburetor, with a top speed of around 65 mph (104 km/h). It had a 103.5 in (2629 mm) wheelbase with a gear ratio of 3.77:1. The transmission was a 3-speed sliding gear unit with a 1-speed reverse. The Model A had 4-wheel mechanical drum brakes. The 1931 editions came with stainless a steel radiator cowling and headlamp housings.

..On the downside, the L-head engine also requires the airflow to make at least a 90° turn to enter the cylinder, which makes it less efficient; colloquially it's said that such an engine has poorer "breathing". Breathing was not greatly emphasized in past production cars because engines could not run long and reliably at high speed due to other factors. This was a minor concern given the benefits in simplicity. Although L-head inline 4 and 6 cylinder engines were frequently used for automobiles, tractors, etc., the best known L-head automotive engine is the early 20th century Ford V-8 , which has both sets of valves (intake and exhaust) located on the inside of the "Vee," and which are all operated by a single camshaft located above the crankshaft.

Open view of the engine and transmission of a 3.3 L Straight-4

..All Model A/AA Ford engines were produced at the Rouge foundry in Dearborn , Michigan with the exception of those engines produced in Canada with prefixes of CA, CAQ, CAW, CAR, CAT, CAY, CAU, CAI, CAO, CAP, CAS, and CAD, and those which were produced in Ireland/England with a prefix of AF.

..The engine serial numbers used the same “style” of numbers up to the end of January, 1931 when Ford changed the style of three numbers only.  Those numbers were 1, 6, and 9.  According to the February, 1931 Ford Service Bulletin, Ford did this “to lessen any possibility of outside individuals attempting to change engine numbers”. This numbering change appeared between A4299173 (January 27, 1931) and A4319643 (February 3, 1931).

View engine left side

..In determining if your engine is an original stamping, the engine number pad, which is located on the left side of the block just above the water inlet hole, must be that of the same “texture” as the rest of the block.   If the engine number pad is very smooth and machined down, more than likely the original number has been ground off and a new number stamped into its place.  Sometimes you can barely see part of the older, original number. (Photo above of the right side of the engine)

..There were three items that were included in the data.  Omitted Engines, Industrial Engines, and A-6005's Engine Assemblies.

..Engines which were shipped to other foreign assembly plants that did not receive the England “AF” engine, more than likely came from the Rouge engines not to mention those that were shipped from the Canadian plant.

View Engine right side

Omitted Engines, of which there were a total of 143992 engines through 1931, may have been those engines that were, according to John Charlton and who is from England and a fellow Model A'er, cast and forged at the Cork, Ireland plant and for which were machined and finished at the Trafford Park Plant in England and were given the AF prefix.  It appears that Ford designated a certain block of numbers, as seen in the data, which were also in the USA sequence of numbers, to appear on these engines.  Once cast and assembled, they then received the “omitted” numbers that were assigned to them such as, AF3019264, May 20, 1930 Tudor (see March 13, 1930 chart); AF3730313, July 22, 1930 Cabriolet (see July 8, 1930 chart); and AF3734739, October 31, 1930 Tudor (July 8, 1930 chart). 

..Today over 85 years later this engines still the power plant for the classic Model A on the road. There simplicity if we compare to today's engine is amazing. I consider them a remarkable piece of engineering in the automobile history ...thanks to Mr. Ford.





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