As values increase, things that were once overlooked as not important suddenly gain importance. This will become increasingly true of engine numbers in Alfa’s 750 and 101 series cars as they grow in popularity and value in the collector car world. Engines, much like VIN numbers have a 4 or 5 digit Tipo number, followed by a serial number, which in some cases starts with a number indicating the model it was fitted to. The engine number ranges I will quote below come from Fusi’s book, which is known to have errors and omissions, if you have a number that doesn’t fit with what is presented, let me know at firstname.lastname@example.org!
A Sprint 10105 build plate indicating Tipo, Autotelaio and Motore numbers. The font of the stamp is correct. Note that this plate is held on by screws. Also note that Autotelaio and Motore numbers don’t match. The serial number of the motor 010669 is included.
This is the engine that matches the build plate above, again note the font. Also of note are the use of stars and the company initials AR. It is difficult to achieve this level of detail when faking an engine number, but if you don’t know anything about how they were stamped, you could be easily fooled.
In 1954, with the start of Giulietta Sprint production, the engine series starts with AR 1315*00001* and runs through *00012*, with corresponding chassis’ numbers 00011 – 00023. Apparently Bertone numbered their prototype cars, but Alfa didn’t number the engines used in prototypes. If I ever run across one of the prototypes at a show I’ll ask to see the numbers and verify whether this is the case. Sprint 750 series engines ran to AR 1315*09002*, then started up at 1315*010001* and ran to *014299* in 1959.
In 1957 Fusi indicates a second group of engines for the 750B Sprints starting with number 00100*03400*, continuing through 1958 to 00100*06903*. I have never seen a Sprint stamped with a number like this and I am inclined to think it is an error for two reasons. For 1959 the engine numbering starts with 1315*06904*, a seeming reversion back to the old numbering system and because of what is on the picture below.
Two things were going on in Giulietta production for 1958/1959. The new 101 models with their numbering designations were being released and the 101 series engines, with their series prefix of 001## were being phased in. In 1958, a Sprint with a 101 style machine stamped body was still called a 750B, probably because it was still being built on a 750B floor pan with open rockers. In 1959, to keep track of the changes and the possible combinations, two new number series were added for the Sprint, the 10105 and the 10102. 10105 Sprints had 1315 numbered engines and 10102 had 00102 numbered engines. This means there were 3 possible combinations for 1959! I have never seen an original build plate for a 10102 Sprint with an 00102 engine that had the rest of the engine serial number.
For 1960 only the 00102 engine series was carried over for the 1300 Sprint’s and Alfa, in an unusual fit of efficiency, started putting the same engine in the Spider Normale. Seeming to pick up from 1315*014299* but dropping the leading zero, 00102 ran from 00102*14300 to 00102*35785* in 1965.
The Giulia Sprint 1600 (not to be confused with the Giulia Sprint GT) released in 1962 had a new engine series starting with 00112*00001*. These engines were also shared by the Spider Normale’s and were made through 1965 ending with engine number 00112*09106.
Alfa recorded the Engine tipo and serial number on a build plate along with model designation and Autotelaio number through about 1959. As far as I have seen, all 750 series cars have the engine number stamped on the build plate. Some early 101 cars also have the engine number stamped, but most seem to only have the engine tipo stamped. As more cars numbers are catalogued it may be possible to show approximately when the engine numbers were no longer stamped. Comparing red car build plates below they stopped between car 20379 and 21131. I have a picture of the build plate for 20825 with the engine serial number, but the plate doesn’t look original to me.
Alfa engines from this period are relatively easy to move from car to car and figuring out the correct engine for your Sprint without a build plate or provenance may be impossible, but you can get ‘close enough’ by comparing similar models of similar age, assuming the engines will be within a few hundred of each other if the cars are. A further confounding factor is the existence of engines without engine numbers, which were used as replacements early on when dealerships were doing repairs on cars with blocks cracked by freezing or catastrophic failure. Alfa may have records matching chassis numbers to engine numbers for all their cars, but an inquiry about your cars history sent to the Alfa Romeo archivist doesn’t usually return an engine number.
Still to come are similar analysis of Sprint Veloce Engine numbers, Sprint Speciale chassis and engine numbers, Bertone body numbers, engine swapping between models and more. Comments and corrections welcome.