The Stovebolt Site Forums The Shop Area Engine Shop Having trouble with 261 identification

I’m having trouble decoding this number. Next to the distributor S0319XXM. 3836850 says it 261, 3769925 I have seen for 261 from 1958 to 62. The truck is 1948 2ton wrecker. So not the original motor. Pretty sure it’s a 261

Edit by Moderator: I moved your post to start a new thread. It’s always better to start your own thread so it’s not confused with the original post. You’ll get info that pertains to your engine.

Ppacker,

Can you post pictures of the "serial number" (next to the distributor). Don't think I have ever seen a factory stamped serial number that included "XX".

The head casting# 3836850 and block casting# 3769925 both do indicate a 261. More can be told if you can post the "casting date" codes for the block (above/behind starter) and head (under valve cover just inside are where the "casting#" is found).

Dan

Working on something else (about carbs), I came across THIS in our Back Room Tech Tips -- "Identifying the 216 / 235 / 261" :: "Quick and easy 216, 235, 261 spotting"

My research says the block is a 1960-1962 261. Head casting number indicates a 1958-1962 261. As Dan sez, find the date code and we can pretty much tell you month and year that engine was built.

FWIW, you may find this Tech Tip interesting. ** click the image **

Hope you can see it S0319XXM. If not I’ll have to clean it up better and take another picture. I believe I have 1948 2ton tow truck with a1958-62, 261 motor and a timken or Eaton 6.1-8.1 two speed rear. At some point they installed a pto to drive the wench cable. So I don’t know what trans is in it yet. The motor was started about 3 years ago. Any ideas on rear replacement. Really low gears. Low and lower.

I have to take starter out to see that number. The one on the head and in front of distributor say it’s 261 motor. Trans is funny. Has pto on the side powering an aftermarket winch. Think it’s a Tulsa 18g maybe model 838. Might have a Frankenstein here. Front lugs are 5 bolt 6-1/4. Other trucks have 8 bolts. Do have 10 bolt rear.

Ppacker,

Yes, the serial number is visible and I think gives us a necessary clue to it's origin.

The use of 2 different size/style stamps would suggest this is probably a replacement engine (they came without stamped numbers) and the shop/installer or some other entity stamped this number to identify the engine.

When you get around to it (if you choose to) add a picture of the date casting codes behind the starter and we can give at least a bit more definitive answer to your question.

For answers on your other topics (transmission w/pto and front/rear axles), post new questions in the Driveline forum for each as it's easier to respond to them separately to avoid any confusion on topics.

Dan

Thanks for the info. The valve cover has the 4 bolts on the edges. I believe the 235 has bolts up thru the top. So far everything is pointing to the motor being replaced. Most likely transmission also since there is a side gear and chain going to a power winch that was added . I think the numbers for it are on the top. It might be awhile before I can get to the starter numbers. Got too much going on. I will post when I am able to get starter out. Hoping to start actual work on it next year.
I found an old license in the truck and it was still towing in 1978 in North Dakota.

Early 235’s did have bolts going thru the top but changed in 1955. 55-62 235’s have four bolts on the valve cover rim like your 261.

Look for the captain's bars on the block between the distributor and the starter to be a 261

Got starter out. Con2 C18 0 on the block with bars. I’d say everything points to 1960 conveyor 2 march 18.

Looks like you have those numbers deciphered correctly!

Mike B