I realize this is an old thread but "Cobra engine number"s (That's 1960s AC/Shelby/Ford cars sold under CSX2xxx chassis numbers. COX/COB60xx and 61xx over seas cars are a related subject but not included below and they have an additional "engine number" topic.) gets asked so many times in so many forums I thought I would put in my commentary for anybody searching this site.
Dan
There are four (4) different sources of “engine numbers” known for new 1963-65 Cobras day one:
#1:Ford Motor Company’s engine engineering department that created very hand built (as in many parts were manually produced as required) prototype engines. In regards to Cobras they were the Experimental High Performance 260 engines. Their serial numbers started off with a prefix XHP-260-. There is some evidence that only thirty five of this type engine were built. Shelby American was not the only user of XHP-260 engines in prototype or production street or race cars.
#2:Ford Motor Company’s engine production division. In regards to Cobras they were HP260 and HP289 engines made prior to about July 1964. We have no idea how many HP260 engines were made but there were at least 137 of them because we know where that one is. Shelby American was not the only user of HP260 or HP289 engines in prototype or production street or race cars.
#3:Ford Advanced Vehicles (in the UK). One new race Cobra is claimed to have been sold with a Ford Advanced Vehicles numbered engine. (Speculation on my part is that the engine arrived at SAI installed in a Ford GT40.)
#4:Shelby American’s production department. Ford ended five bolt block engine production before all Shelby’s chassis stock received engines. We don’t know how many were ordered but 48 each odd or hybrid (model year wise), part 1964 specification and part 1965 specification, tagged as 1964 models made in the 1965 model time frame, were delivered. Ford did not serial number them so Shelby’s works created their own numbering system. These engines, made just for new Cobras in August 1964, didn’t cover all the chassis without engines. 42 of the engines were installed in new Cobras, one was used as a warrantee replacement to an owner that damaged one of the 48 racing, and the rest are unaccounted for. Fifteen (15) addition cars received 1965 model year specification Fairlane HP289s built specifically for automatic transmission. These were 1965 model year production so they were based on six bolt blocks and they received numbers assigned by Shelby’s works.
Cobra chassis were not finished in strict chassis sequential serial number order in England, a good example is the test and development chassis CSX2126 was completed before CSX2080. Cobra chassis were not shipped from AC Cars to the east coast (to Hugus) or west coast (to Shelby) in order. Once in inventory in the U.S.A. rolling chassis were not pulled from stock in numerical order to get engines, transmissions, and cooling systems installed to make them running cars. Engines were ordered from Ford and delivered in lots. Evidence suggests that HP289 wise engines were pulled from Ford stock at random and shipped to Venice California. Shelby American apparently had no ‘first in first out’ inventory control as once an engine was stored it could end up in any Cobra street or race completed after that. In studying chassis, when those chassis became running cars, and engine numbers there is no pattern except there couldn’t be an engine made in July 1964 “original” to a car that first ran in February 1963.
Comparing two consecutive chassis numbers and their engines will usually not be very enlightening as there can be a few to hundreds of engines in between the two chassis; engines made in different time frames and maybe even in different model years. Example: Two consecutive VIN chassis sold as what Shelby American described as “1965 COBRA” cars have engines separated by 952 other engine serial numbers. In that pair of cars the highest serial numbered engine went into the lowest serial numbered chassis. One of the largest “spreads” in “engine numbers” I have come across was in the CSX24xx chassis contract of 6,734 engine serial numbers between a 1963 made engine and a 1964 made engine. If you understand that Ford made running changes in subassemblies and final engine assemblies over time, especially between model years, it is also clear that determining how any particular Cobra might have been equipped is not quick or easy. To have any idea how the drive train in a new Cobra was probably finished out one must know the Cobra chassis number, who completed the car (Shelby’s Venice works did the most but they were not the only shop-crew-state-country), the documented engine number associated with the car, and the engine assembly date stamped into the engine block.
