SixT5HiPo wrote:Those early 260" COBRA engines are little known or documented except in the exclusive SHELBY books...The HP 260 is the "first generation" thin wall small block performance engine that ultimately led to the design and production of the much improved "Fairlane" 289 High Performance engine that was introduced by mid year 1963 .
More is known than widely published. Most of the questions asked that I come across are asked by people building a replica of some sort (Rally Falcon or early Cobra facsimiles mostly). I have met or know or known several owners of early Cobras that originally used some type 260 c.i.d. and none of them have any active interest in the subject of 260 engines. A friend owns a Cobra originally fitted with a HP260. The original engine was replaced during the car's days of SCCA racing. He has some of the original engine and he doesn't have enough interest to clean it up and display it on a stand. I wish there was more interest as I don't have a use for the COBRA intake, spacer, correct carburetor, and distributor that I have for a HP260 powered Cobra. Circa 2008 I was hoping to gather enough parts to assembly a complete engine. I found everything but an engine block (all once used in new Cobras) but the owner just didn't want to sell them.
Engine XHP-260-4 (experimental high performance 260 serial number 4), which started off as serial number 2 and was remarked 4, is mostly intact and unrestored. It was installed in one of the first few new Cobras before being replaced by presumably a HP289 engine. The engine had a few mostly external modifications for use in a Ferrari race car. The Ferrari was raced with the “Cobra” engine. The engine stayed in the Ferrari until a friend of the owner talked him into returning the car to a correct type Ferrari engine. The Cobra engine came out circa 1993 and was stored until I asked Bob Mannel if he would do one of his analysis of the engine.
Bob carefully dismantled the engine and took hundreds of close up photos of details in the manner as he did for his small block Ford V8 engine book. Many of the small parts in the engine were preproduction or prototype parts and very many had individual part serial numbers hand marked on them. Many of the valve train parts are not like any other Ford parts. Some parts appear to be the parents of what would become HP289 parts, connecting rods for example. Even small parts like bearing inserts were preproduction parts. One surprise was how early in 1961 some of the parts were dated.
Bob reassembled the engine. In cases, like gaskets, where originals would have been impossible or impractical to replace with 100% matches he used the closest original Ford parts available. The engine and signs describing some history of the engine and the parts that it was assembled with were on display at one show.
XHP-260 engines were hand built by Ford engineers with many hand built parts, I can only come up with a number of 35 engine made and that is based purely on the serial number of the experimental dual point ignition distributor installed into engine XHP-260-1 that proclaimed it was the 6th of 35 assemblies. Cobra wise I have only come up with serial numbers to XHP-260-14 but record keeping for Cobras in the first six months is not as good as it got later.
HP260s were almost regular production ready engines and Ford made at least 137 of them made (my guess was that at least 200 were made). (There is some evidence that Ford had considered offering a HP260 powered Ford Falcon. Dearborn Steel Tube built a prototype car for Ford testing and that car was road tested by a magazine publisher. For whatever reason or reasons the special option package for Falcons failed to materialize.) I have the original oil pan, rocker arm covers, and cam shaft from HP260 serial number 137. HP260 engine 137 was installed in a new Cobra but replaced by a HP289 soon after. A man bought the barely used engine from one of Shelby’s famous garage sales in the summer of 1964, installed it in a hot rod, and drove the hot rod for almost five decades using it. HP260s are made of mostly Ford production parts. The cylinder head assemblies, connecting rods, the cam shaft and lifters, intake manifold, and ignition distributors are their unique parts. The only parts you can see of course are the iron intake manifolds and Ford production mechanical dual point distributors. I have a HP260 distributor than came out of a Cobra.
The most visible part of a XHP-260 or HP260 engine is the 4V intake manifold. The life time of these engines was roughly between April 1961 (when some unique XHP-260 small parts are dated) and fall of 1962. Quantities of engines were small but development and experimentation was rapid so there are a number of 4V intake manifolds used with these engines. Ford provided a family of cast iron parts. Holman-Moody provided a family of cast aluminum parts which they, Ed Hugus (early Cobras), and Shelby American used as weight reducing options.
From my notes:
The family of intakes (small numbers of several variants used by Ford or Holman-Moody or Hugus or Shelby's companies) were created for Ford XHP-260 and HP260 engines. That means runner and port volumes are sized for racing 260 c.i.d. Ford engines in terms of 1961-62 technology. Every Ford intake for 289 c.i.d. engines has larger runners. There was a final 260-4V version of an intake manifold for Sunbeam Tiger 260 Ford engines offered as an over the counter or aftermarket accessory. The Tiger specific Ford 260 engine assemblies are not the same as HP260 engines.
1st design iron Ford prototype XHP-260 (installed on at least the first eight XHP-260 engines), 260 engine sized ports. Cast in SK 12569 “sketch” engineering number. Sometimes these will have in a second SK prefix engineering number hand stamped in along with a unit serial number. 1962 Fairlane style heater hose port in left front of carburetor location.
2nd design Ford prototype HP260 design iron, ports are 260 engine size. No cast in engineering number. Heater hose port now moved close to coolant outlet somewhat similar to 1963 production 2V and 4V models.
3rd iron Ford version, the production ready HP260 (many more engines were made than most people are aware of) – These are 260 engine size. Cast in identification was a 1962 model year Fairlane engineering number C2O 9425-K (The casting definition is poor where the text is and it is believed the text was suppose to be C20E-9425-K.) and directly above the Fairlane number was a Ford engineering experimental number of XE 10639.
4th cast iron version by Ford, a production HP260 piece, 260 size passages. Cast in identification was a 1962 model year Fairlane engineering number C2OE- 9425-K. The Ford experimental number has been dropped by the time this version was produced. While possible to have been part of a new Cobra engine none have been confirmed.
1st Holman-Moody Rally Falcon HP260 aluminum version with a few different final machining variations during their short life time in use (all aluminum versions based on 2nd iron design and one master mold that got modified permanently for each change), parts are 260 engine size and were machined differently for different applications, Lee Holman believes most went into marine applications. The cast in identification is a Holman-Moody engineering number of HM9424-1.
2nd version aluminum is same as first except HM bird machined off, I don't have a picture of one, still 260 engine size passages, one of these intakes was shown well in a new Cobra road test article in 1963. Again the cast in identification is a Holman-Moody engineering number of HM9424-1. Shelby American registered this style 1-4V intake with the “FIA” 11/30/62 under part number XEO-113.
3rd aluminum version, HM logo replaced with raised rectangular boss, still 260 engine size passages, I have never seen one in person but one was for sale in an ebay® auction in 2013 with the Holman-Moody part number ground off. A Shelby factory advertisement in a magazine article for brand new Ford 260 powered Cobras shows this style with lettering as a decal I believe like racing valve covers had. The magazine article claimed that this was now the stock intake for new 1963 Cobras. As produced and shown in Shelby factory images they have the cast in Holman-Moody engineering identification number of HM9424-1.
4th and final COBRA application aluminum version, still 260 engine size runners, offered and sold as a
regular production option all the way into the completion of CSX24XX chassis (yes with HP289 engines). (Special Note: A first person report by an original Cobra owner indicates they were not suited to any kind of racing on a HP289 engine. The person indicated that every 4V intake of any type or brand made for a 289 sized engine that was tried worked better.) The cast in identification on this COBRA lettered intake included both the Holman-Moody engineering number of HM9424-1 and a new Ford/Shelby C4SA9421 engineering number. The May 1965 parts book lists it under a S1CS-9421 sales part number.
1st TIGER version (sold by Shelby American), for 260 engines, has road draft/PCV port (owner plugged in
this image – Ford/SA sold a steel block off plate that bolted on). The cast in identification on this TIGER lettered intake was the Ford/Shelby C4SA9421 engineering number.
2nd TIGER version (sold by Shelby American), aluminum, still 260 engine size runners, no road draft port