I've been trying to find info on the 1956 265 cu. in. 240 hp. engine and have found an awful lot of conflicting info both in on line searches and from small block lovers on here. So far what I've come up with is that the 240 hp. was a Corvette only option even though there is some mention of this engine being in some passenger cars. I've had small blocks a long time ago '66 Nova, '65 'vette, '68 vette. etc but that was a long time ago so I'm really out of touch with these things, I've been looking at a 265 that the owner has been told by a small block "expert" that it is a 240 hp. I'm finding conflicting info on line as to this claim and would really like to get it cleared up. The engine in question has a suffix on the ID. # of GS which from what I can find is a 225 hp. stick shift dual exhaust passenger car. The intake is 3731394, heads, 3734077, Carbs 2419s, and 2362s heads have the two tower casting. Was the only difference between 225 hp. and 240 hp. the high lift cam? I saw in one search that the 240 hp. was over rated and didn't produce that much hp. So was it just a 225 hp. with a different cam promoted as a racing engine? Any help would be much appreciated and thanks to all who have tried to help out so far, just an awful lot of conflicting info out there on these engines.
The 240 HP version of the 265 was intended to be a Corvette only option. The stamped engine code was "GU" for the 240 HP engine, while the 225 HP version had an engine code of GR. These codes would be for engines with standard transmissions. The difference in the engines was the camshaft. The 240 HP version was the first to use the famous "Duntov 097" cam. The '56 version of this cam was for use only in the 265 cu. in. engine due to the oiling notch in the rear bearing journal. The heads on both the 225 HP engine and the 240 HP engine were casting number 3731762. However, some of the earliest 225 HP engines used the Power Pack "306" heads. The 3731762 heads did have the two tower marking but there were later 283 heads which also used this same marking.
The engine codes which I gave in my earlier post, GU and GR, were for these engines for Corvettes. The GS designation would be correct for a 225 HP engine in a passenger car with standard transmission. The 240 HP engine in a passenger car would supposedly have been stamped "GT". The intake manifold on all of these engines would have been 3728725 for the earliest 225 HP while later engines would have the 3731394 manifold for both 225 and 240 HP engines. The distributer should be 1110872 or 1110879. I do not know if there was a difference in these distributers or if either was exclusively for the 240 HP engine. The carbs used on the 3731394 manifold were 2414S and 2362S. The exhaust manifolds which were used on the later 225 and 240 HP engines were 3731557 (left) and 3731558 (right). These exhaust manifolds were the ones used in conjunction with the 3731394 intake. The earliest 225 HP engines had different exhaust manifolds.
The head casting number given in the original post did not make any sense. I have never seen heads with this number, but the number itself looked familiar. The number, 3734077, is actually the casting number for the camshaft for the 240 HP engine. The camshaft part number is 3734078 for the finished cam, but the 3734077 number is marked on the shaft. (The 283 and 327 version of this cam has the "097" number.) So it appears that the engine in the original post may, at least, have the 240 HP cam.
Here's the carb tags, this the only thing I think we differ on except the cam which I don't have a pic. of.
OK, now for the big question, what is the difference in value between the 225 hp. & the 240 hp. engines? This one has never been apart as far as I know and I've known about this engine since I was about 12 yrs. old (68 now) only 3 owners it was taken from a wreck in about '57-'58 and installed in a '46 convertible and was sold to the current owner in '94 he has driven it all over the country and just pulled it a couple years ago and installed a rebuilt 283.
Not specifically the 240 HP, but may be interesting reading. http://www.55chevys.com/ct/56dualquad2.jpg
It would be interesting to compare the casting dates on the block and heads of this engine. The 1732 heads and 1394 intake were not available at the start of the 1956 model year. Also, the 240 HP cam was not available until even later. The cam supposedly first appeared in the Corvettes which were entered in the Daytona speed trials in 1956 and then became a regular production option somewhat later. Again, the information which I have says that the engine code should be GT if it was a 240 HP, standard trans, passenger car. For this engine to be a true 240 HP engine, the casting dates would be expected to be no earlier than January 56 or perhaps December 55. With regard to value, I do not think there would be much difference today. A complete 225 HP engine is difficult to find (or to piece together). Of course the 240 HP passenger car engine may be a unicorn, which may never have really existed.
The 225 and 240 horse motors were both 2x4 motors. The 225 could be had in a sedan if you ordered it that way, I suppose you could get the 240 horse motor in a sedan too. I have not seen a 240 horse motor in a sedan but I have seen a couple that I know came that way with a 225. The difference in the 225 horse motor and the 240 horse motor was compression, one being a 10:1 ( some books say 10.5:1) and the other being an 11:1 (or 11.5:1) and what GM called an off road cam. Very few 240 horse motors were sold they were primarily a road race motor. Here is some information for you that may help this is accurate as far as I know it to be: Location Of Engine Code: Stamped on the block in front of the right hand cylinder head. Letter Code Engine Horsepower Torque Transmission Carburetor FG 8-265 225 270 Powerglide 2 - 4 BC FK 8-265 210 270 Powerglide 4 BC GR 8-265 225 270 3-Speed Manual 2 - 4 BC GU 8-265 240 270 3-Speed Manual 2 - 4 BC GV 8-265 210 270 3-Speed Manual 4 BC The 270 is a torque number and the HP ranges from 210 to 240, the table didn't transfer well so you may have to strain your brain to understand it but I am sure that you can decipher it if you try.
I thought that we were talking 265" corvette engine the information that I posted was all 265 inch and they never made a 265 that built 1 horse per inch. At least not from the factory that anyone one of us could have ever owned. The compression ratios that I posted were from memory. So I could have been off a point, the real difference between the 225 horse 265 and the 240 horse 265 was compression the cam difference was minimal and the real producer of zot was the compression difference.
ALL Chevrolet 2 barrel engines were 8:1, ALL 4 barrel and 2 X 4 barrel engines were 9.25:1 in 56. The difference in CR was in the heads used, specifically, the combustion chamber size. The early 56, 4 barrel/dual quad heads were the same 5603 castings, while the later 56, dual quad, 1762 casting heads, had larger ports and shape. ALL had true flat top pistons, without any valve reliefs. The 240 HP was arrived at with a "special high lift" cam, RPO469, a strictly Corvette option Things changed in 57 when some engines did come with domed pistons. That's a fact Jack! I am Butch/56sedandelivery.
OK, so from the #'s I've been able to find in my searches there were 111 240 hp. corvettes produced and somewhere north of 3000 225 hp. engines both corvette and passenger car. Which I would think the 225 hp. would be worth less, but seeing that they both used the same heads, intakes and just a different cam maybe not???? But for a collector of Corvettes you couldn't very well take a GS engine change the cam and call it a 240 hp. in a corvette. So in that case it wouldn't be worth much other than the heads and intake could be used if you had the right block or fudged the #'s. So what is a 225 hp. worth?
I've been hunting for a GOOD, 56, 265 block for a few years; all have been rusted up, damaged, POS, that people think are made of unobtanium. I had to "settle" for a 57, 265 block, but it has better features too, such as full pressure oiling ALL the time, and a block mounted starter provision. You have an almost complete, 225 HP, 265. To a restorer, a block can be decked and renumbered; you think that's not done? A cam change then upgrades it to 240 HP specs; the aftermarket can copy a factory cam. Your engine masy have come from a passenger car, but any Corvette restorer would snatch it up just to clone it. Join one of the Corvette forums, and ask what THEY think it's worth; the guys that really want what you have (or about to have). I'm sending you another PM with some info I've held back; someone who CAN answer your questions. I am Butch/56sedandelivery.
I knew several guys that bought new 1956 Chevys with 225HP motors, if 240 was available they would have had them. One was Ron Hassel a C gas national champion. My understanding was the 240 didn't come out until 1957 which was a 283.
Yes it did, see 56Ssdandelivery's post above. He knew his 265s. I was just pondering this last week. My '56 Vette has the 220hp (according to the stamp). One of my beater work trucks is a '96 S10 with a Vortec 4.3 (262 CI). The Vette engine feels is soo much better! It does suck more gas...
Damn it was good seeing ol Doodlrodz name pop up, I almost forgot.... Then I see Butch 56Sedandelivery too.
Here are the cam specs I found- the 225 horse cam had .404 lift/264 duration IN and .413 lift/266 duration EX with the difference for the 240 horse 3734077 having a duration of 287* with the same lift figures as the 225. The ‘077 cam was designed by Duntov and it later evolved into the ‘097 which kept the 287 duration with lifts of .394 IN and .400 EX. Also I think the 240 h.p. engines were the first to have notched pistons.
I never saw .050 figures posted online from Chevrolet for any cams, in fact the vaunted L-79 hydraulic was listed by Chevrolet as having 320* duration, but I think that was at a checking figure of .006 IIRC. When checked by cam grinders or engine builders they were 222* @ .050. If we could check the ‘077 240 horse cam with its factory value of 287* I bet the duration might be a real eye opener at .050, it would look very tame by todays standards. Those early Chevy performance cams had a gentle rate of lift off the heel of the cam and that was one secret to their success on both the street and track even with factory springs with only 80# on the seat and maybe 180# or so at full lift. I can’t say if anyone ever checked the ‘077 at .050, but I’ve seen the ‘097 Duntov figures at that value. I won’t be home for another week or so but maybe someone can post those numbers just for comparison sake.
"The 265 arrived on the scene with a 3.75-inch bore and 3.00-inch stroke (95.2 - 76.2 mm). It made 162 horsepower and 257 lb-ft in base form with a two-barrel carburetor. An optional Power Pack added a four-barrel carburetor (and other modifications) taking power up to 180 horsepower and an even 260 lb-ft of torque. When fitted to the Corvette, the 265 made 195 horsepower through a dual exhaust system. Later in the year Chevrolet added a Super Power Pack option to the Bel Air, taking it to Corvette power levels." "In 1956, the 265 in the Corvette was available in three more powerful flavors: 210 horsepower with a single four-barrel carburetor, 225 horsepower with "dual quads," and 240 horsepower with the dual four-barrel carburetors and a high-lift camshaft. Its compact size was made possible by consolidating accessories. According to GM, it used a one-piece intake manifold that combined the water outlet, exhaust heat riser, distributor mounting, oil filler, and valley cover into a single casting." https://www.motortrend.com/features/small-block-chevy-v8-through-the-years/ Hello, When my brother’s teenage friends started coming over to our Westside of Long Beach house, I was impressed with the different types of cars that showed up. From a 1934 Ford 5 window coupe/Oldsmobile powered to a 37 Chevy 4 door sedan, to a green and white 56 Chevy Bel Air Hardtop. Most of the teenage cars had some form of drag racing done in their timeline. I was able to film the Green and White 1956 Chevy Bel Air at Lion's Dragstrip during this time period of the late 50s. The 1956 Chevy came with a 265 motor in different stages of development. It seemed like that was the car that was going to give the 1934 Ford 5 window, Olds powered, the most challenge in a drag race. The motor looked stock, but my brother told me later, that his friend always kept what was inside, a secret. When the 4 barrel got a new addition one week, now, it looked like the above mentioned 240 HP dual quad motor. Knowing this teenager, he probably had his own modifications inside but never told anyone. So, assuming 240 hp at least. Living near Jocko’s, the Cherry Avenue Speed Shops and Hot Rod accessory shops was an advantage. From the outside, the 265 SBC motor looked like a Corvette motor, but we had no idea what else was done to the motor. It is hard to see, but it may say C/Stock or C/Gas. C/Gas seems right, as it was modified, but there were those guys that ran in the stock car classes at Lion’s Dragstrip, because it looked completely stock. He won, but never had to tear down the motor on a protest. It could have been the time line of the stock 265 bored out to a 283 c.i. with some other modifications, head porting, cam, pistons, etc. But, no one knew for 100% certainty. 56 Chevy Bel Air at Lion's Dragstrip Jnaki The final episode of this 56 Chevy was a drag race against my 58 Impala. It was rumored that he had modified his 265 to the limits, so he got a 283 motor and had Reath Automotive enlarge the motor to 301, then finally, to a 352 c.i. with a stroker kit. He had known me from coming over to our house plenty of times. He knew my brother’s 58 Impala, but with the new C&O Stick Hydro, plus internal modifications, it was a different ball game. I got off to a car length lead with the power and C&O, but soon after, I was waiting for the other two carbs to kick in and take off. That did not happen, but we were still neck and neck. He was looking over at me and smiling, but not pulling away. He knew his limits. But, I was still waiting, knowing something was not right. So, after the race with the 56 one bumper ahead, we headed back to the drive-in restaurant parking lot. Upon arriving, I opened the hood and found what was the matter. I was racing with the center two barrel carburetor alone, as the vacuum hose fell off and was sitting on the manifold. Instantly, I put it back on and clamped it down. When my brother’s friend saw what happened, he declined to race against my full power, knowing the Impala had not used the full power of the modified 348 motor. there was some excuse to re-race that night, claiming something happened to his motor, too... Even if he did have a 352 stroker motor, I knew the full power of my 348 could easily whomp his so called 352 SBC sedan, but with all three carbs running. With the full power of the modified 348 motor and the C&O Stick Hydro, there was no way the race was going to be close from the start. But, as an 81 year old guy, he still laughs at the mention of the race...
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