I built this 261 motor years ago. It's an early model with the short water pump. It also was not a full flow oil system. From what I can find, the full flow oil motors came out in late 1954/55. So mine must be older? No captain bars on the L side & now that the motor is installed in my 39 Chevy with dual intake & dual exhaust, in my tight engine compartment, I can not see if there are captain bars on the R side. I have a machined 235 head on it. I do not have the original distributor & mine is probably newer than 54, "not sure"? I have not started the motor yet. Now I find that around 1954/55 GM also changed the material they used on the oil pump gear on the cam & on the bottom of the distributor. Now I'm scared to start the motor. From what I read, the motor ID# should be cast on the block right above the starter, or in the earlier models it may be in-front of the fuel pump. No #s in front of the fuel pump, just GM in the casting. Above the starter it reads, CON 3 62/. The forward / may be a # that did not show-up completely during the casting of the block? That still would not be enough #s, but that's all that is in the block casting. Stamped in the block right behind the distributor.is #s 50918. I called Jim Carter & they guessed by the stamped #s it may be a 1950 motor because the first two #s are 50, but they were guessing... The Distributor serial.# is 1112403, but I have not found any one that can determine the year from those #s. Does any one know were I can go to solve this problem???
The 261 came out in '54 I think, the full flow in '58 or '59, so yours can't be older than '54 (as I recall). I'd say do what you can to get the casting numbers off it (mirrors and flashlight will help), might try the stovebolt site.
Now I find that around 1954/55 GM also changed the material they used on the oil pump gear on the cam & on the bottom of the distributor. Now I'm scared to start the motor http://www.langdonsstovebolt.com/tech/camshaft-cast-iron-or-steel-how-to-tell/ http://www.langdonsstovebolt.com/tech/casting-numbers/ http://1954advance-design.com/Web images/261-engine/index.htm http://www.secondchancegarage.com/public/1958-chevrolet-235-145hp-6-distributor-specs.cfm 1958 Chevrolet 235 (145 hp) Inline 6 Engine Distributor Specs Distributor part number: 1112403 http://vcca.org/forum/ubbthreads.php/ubb/showflat/Number/130885/Main/21233/ 1112403 was originally for 1955-1962 6 Cyl. Then its application kept backing up and by the 1960's was described for all 6 cyl. engines from 1940-1962. First the gears. Yes, when Chevrolet changes from a forged camshaft to a cast in 1954 (except some solid lifter engines) they changed the gear material to make it combatible with the cam material. At that time there were two different gears made for replacement. Later the newer gear was sold for all applications. It my experiance I have never seen a later gear being eaten up when used in a forged cam engine.
The #s I see right behind the starter is all there is, unless there are more #s down so low the starter will need be removed to see them? Would they be at the very bottom of the block? below the #s I quoted earlier?
OK, I think I got it figured out. The gear on the crank is definitely the wider 1/2"+ gear. So it must be OK to use this distributor since it's from 55/58... After looking real close I felt another something on the block. It must be an "I", not a "one" since the photos show a letter in-front of the last 2 #s? The block casting#s must read CON 3 I 6 2.. Thanks again for the help.
This seems to be your main concern. You don't need the year, all 261 engines are 1954 or newer. '54 is when they changed cam & gear material. The first Langdon URL above tells you how to identify what the cam is made of. This is how to identify the distributor gear according to (http://www.chevytalk.org/fusionbb/showtopic.php?tid/79723/) It says: The most important thing is to use the correct gear to match the camshaft that you are using.Camshafts up thru 1953 were steel and used steel dist. gears,From 1954 and up (some exception on early 1954 sticks) the camshaft and gear is cast iron.(cast iron gear has a groove at shank of gear teeth.If they are mixed they could "eat each other up"
I trust you mean the cam. Yes, you should be ok. The casting number will be a 7 digit number on the surface in front of or behind the distributor. I have a 235 with the casting number in front of the fuel pump mount way to the front down low just above the pan flange. It could be there too. I had to dig off a lot of grease to find it. Those numbers are quite small. One thing I ran across showed it in the center of the engine on the manifold side down low.
Yea, it makes seance that the to different metals not holding up. Thank you... After looking at the casting #s again, I can see all the cast #s very clear.. I'm not sure why there is only 3 digits after con 3, All three are spread apart, the first is either an I or a one? than a 6 than 2. It's so clear that you can see the in-prints if the small screws that held the stamping plate in place. There is no room for more.
You should have a serial number stamped directly behind the distributor. '54 261 codes begin F54Q or N & T54Q or N. '55 1st series will be F55Q or F54Q55; and F55N or F54N55. Source is '64 P&A Chassis book.
If I remember correctly CON 3 is a conveyor number. The 3 numbers after that are the casting date code, see http://1954advance-design.com/Web images/casting-code-photos/codes-ser-nums.html for decoding. As you can see from the pictures the block casting number may be at least partially under the motor mount. The block casting number will be 7 digits. See http://1954advance-design.com/Stovebolt-engine/casting-numbers.html for the years that the numbers were used. Scroll down to the 261 (green) section.
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