The Stovebolt Site Forums The Shop Area Engine Shop are these captains bars?

Right side of block has what looks like the number 11 turned sideways (pics attached), but it doesn't look like the captains bars I've seen in pictures. Is that what they are?

Stamped serial number 0496758F55N seems to confirm it's a 261 from 1955. Also, head casting 3703570 indicates 261 head. Would the CON4 G57 indicate July 1957? Doesn't make sense for a 1955 engine so I'm confused. Haven't found any seven digit casting numbers anywhere else on the block, and no captains bars at all on driver's side.

Skooter -- The experts will chime in soon, but in the meantime, all I can tell you is that not all 261's have the "Captain's Bars"

My 261 is a crate motor out of the 3733950 mold (for the ''54 qand '55 1st series trucks). There may be more than one mold for the 261's built for the last of the Advance Design Trucks (with the high water pump). Someone with better access to a casting code decoder ring can tell you for sure about your code. You also need to decipher the date code, too.

v/r
John

Skooter,

Perhaps the below picture will better help you know where to look on your engine for the block casting number.

Right side, forward and below the distributor opening but behind the fuel pump mounting boss, about midway between the oil pan to block mount flange and the bottom edge of the push rod side cover.

Find that number and we can get the decoder rings a-twirling.

Look for the block casting number just above the oil pan flange on the passenger side near the front of the block...it' will be under a layer of crud.

CON4 is of no value to us, it was the conveyor number the engine casting was made on and it helped identify where to look when problems in the casting process happened.

Casting date code G 5 7

G = July
5 = Day
7 = Year (1957)

So it looks like you have a replacement engine done under warranty as it got the original serial number transferred to it.

Mike B

Between and just below distributor hole and breather tube hole definitely not there on this engine. Got a good bit of crud scraping left to do!

Interesting, didn't know they transferred original serial number to replacement engine. Makes alot more sense now. Still got buncha crud chiseling to do above oil pan flange and elsewhere.

Skooter,

I did a little more searching and came a cross this quote in a VCCA chat conversation about 261 casting code locations: "The block codes are in various places on the fuel pump side of the engines. The casting number on my 261 which I believe to be 54-57 is located in front of the fuel pump down low near the oil pan."

Sounds like one last good spot to clean and check. I think the indication is the number is down just above the oil pan flange, right in the midst of all that wonderful crud in front of your fuel pump mounting boss. Sorry

Skooter,

Here is one more linked picture that will help give a better idea of where to find that farther forward casting number: http://www.langdonsstovebolt.com/wp-content/uploads/2014/01/235_261_50_TO_54_CASTING_NUMBER_PIC.jpg

Let us know what you find.

Bingo. 3733949 Although I'm finding that number as a 235 casting number, not the 261 indicated by the serial number. Will be up bright and early to pull head and measure cylinder bore.

Skooter,

Glad you were able to find it finally.

Lots of different sites (inliners, VCCA, etc.) decode that as a 235 for sure, with some specifying 53-55 1st series, 53-54, 54 only or 55 1st series only (guessing that may have to tie in with the casting date codes to define better).

Either way, definitely a "235". Your internal inspection should lock that in tomorrow.

Have a good night!

Per my parts books casting number 3733949 was used for ALL 1954 235 (exc PG) and 1955 1st series 235 trucks.

I'm betting by 1957 Chevrolet was scrounging around to find enough casting molds to make replacement blocks for the now obsolete engine (that had been out of production for 2+ years), so that they used whatever they had. So, you got a 235 casting number with sideways captian's bars (made with a screwdriver pushed into the sand cast) that was built as a 261 for warranty replacement. And since most vehicles were titled using the engine serial number prior to 1955/56 it was sent out with the serial number stamped on it from the factory confirming it's size and the exact customer it was going to.

Mike B

Removed head and confirmed, 3 9/16 bores indeed, so it's a 235. Which might be ok because 235 parts seem to have greater availability than 261 parts. There's very slight ridge at top of middle two cylinders, will catch a fingernail but the ridge doesn't go all the way around the bore. Outer four cylinders have a trace of carbon, but no ridge that I can feel with a fingernail. Will be doing Hotrod Lincoln's technique of measuring taper pretty soon: https://www.stovebolt.com/techtips/engines/cylinder%20taper/index.html

Got a good recommendation for local machine shop, will likely farm out most of the critical measuring and more. Now that the big question has been answered I'll be taking a slower approach from here on out. Just want a solid reliable engine and will try to keep my bumbling self out of the way in the process to make sure that happens.

Excellent info, thanks a bunch. Really think that's the number 11 though, after picking some more crud out of the edges. Saw another 261 or 235 engine pic (forgot where) that had a 17 in that location, also sideways to the date code. No idea what it means.