The Stovebolt Site Forums The Shop Area Engine Shop 261 or 235?

Evening all,

I've been going through all the data sources regarding casting numbers, serial numbers and date code stampings and can't seem to find the answer to the question of what kind of engine I'm looking at so I have come to the source of all info.

I'm looking at what is advertised as a '53 Bel Air 235 with an "automatic" transmission (presumably powerglide). The head casting # is 3701887, which, according to http://1954advance-design.com/Stovebolt-engine/casting-numbers.html site, is one of the "last low-pressure 235" engines. The date code stamped on the passenger side of the engine is H 203, and there appears to be another number after the 3 that appears to be another 3 or a 0 or just a mark. That, again according to http://1954advance-design.com/Stovebolt-engine/casting-numbers.html, makes it August 20, 1953 build date. HOWEVER, on the passenger side of the engine, just above the starter are a pair of "captain's bars" which, according to just about every source I've read makes it a 261. So, as Vinnie Barbarino used to say, "I'm so confused".

I'm waiting to get photos of the block casting number and serial number.

Could this have been a 261 that, for some reason, someone put a 235 low pressure head on? If so I'm guessing that's not a good thing. What sort of damage would this have done to the 261?

Anything in particular I should look for when I got see the engine?

Thanks in advance,
Joe

Sounds like you have a 261 block and an early 235 cylinder head.

There are much more experienced people that will weigh in soon, but when I was looking for my 261, I ran into a couple that had JB Weld smeared all over the sides of the block in places. I quickly passed. This indicates cracking of the engine block. Is there any history of the engine? Does the owner know anything about previous rebuilds?

The serial number from the block will be the key to identifying your year of 261. These engines could run several different cylinder heads, and you will hear of the "848" head that I believe was offered on the 235 car engine, that raised the compression slightly. A 261 engine has additional coolant passages drilled in the block, and some recommend that these additional 6 holes be drilled into the 848 head if it is to be used on a 261.

I just bought a 261 last weekend so I am learning as well. It will be rebuilt and go in my '53 1/2 ton.

August of 53 would put it in the realm of 54 model year (August retooling) which is first year for 261. 53 powerglide Head, i don’t think any damage. Frankly, the block is what you want if it’s a 261. The 54 blocks are the stouter of the 261 blocks in that the cylinders are thicker and can be bored larger, read that, good for rebuilding. Will wait to see the casting number and a photo.

It has been reported that some 53/54 235 engines had one set of captain bars similar to the ones found on 261 blocks.

Apparently, in 1953, the powerglide 235 car engines had captains bars by the starter.

Thanks Mike,

Hopefully I'll have the photos of those numbers later today.

Joe

Well there's nothing like adding to the confusion. Hopefully the other numbers will tell me what I'm looking at. I'll post them as soon as they come in.

Joe

I just noticed in the one photo that the valve cover is held on by the 2 bolts on the top. So unless someone switched the heads this couldn't be a later 235 or 261 head.

http://chev235guy.blogspot.com/search/label/Identifying%20a%201953%20235
My blog post about 1953 engines.

Morning Dave,

Thanks for the post on the '53 engines. As noted above I'm still waiting for the block casting number and serial number. The date casting number on the block is August 20, 1953 and there are "Captain's Bars" just above and to the left of that number. The head casting shows it's a 1953 head, the last of the low pressure 235s as noted in the 1954Advance-design website. Your info seems to indicate it is a full pressure engine since it has the bars. I guess it will take the actual numbers from the block to tell me what it is.

Joe

FYI, in 1953 both splash and full pressure 235 heads interchange, and also fit the 1954-62 engines.

I still have my fingers crossed for you that it’s an early 54 261. On the other hand, I did not know about captains bars on the 53 powerglide blocks. It never ceases to amaze me what I learn around these parts!

JoeR,
Regarding the valve cover held by two bolts, it still could be a later 235 or 261 head. All you have to do is use the long studs when attaching the rockers. An example is my '50 COE which has a '58 engine block and head. They had to use the splash oiler valve cover that originally came with the truck because it has no provision for filling the oil due to the fact a filler would not fit or be accessible under the floor (doghouse). You fill the oil through a cap in the road draft tube.

A quick look to the drivers side of engine block for the presence (or lack) of an "oil distributor" cover plate to distinguish a combined versus full-pressure lubed engine: then look at the engine serial number on the flat boss near the ignition distributor. A "Q or S" in the engine serial number is RPO Powerglide "full pressure" 1953 235.5

Hi Soggy,

I'm waiting for the numbers from the seller. The one photo I have it's hard to see if the cover plate is on or not.

Joe

p.s. RPO?

Ah well, it's a 235, casting number 3701481. So that makes it a full pressure block, but the head is a "low pressure" head, which I guess is ok. But it's not the elusive 261. So Tim is correct about the captain's bars on the '53 Powerglide 235s. Not sure if I should make the hour and a half journey or just get the '54 one that's a mile or so away. For less than half the price I'm going to go look at that one first.

Thanks for all the valuable info.

Joe

Joe:
RPO is GM abbreviation for Regular Production Option

The block casting # 3701481 is for a Chevrolet 235.5 cu Passenger Car with Powerglide Transmission.
The cylinder head #3701887 matches all stock 1953 235.5cu engines for that car.
That engine used the SAE (Society of Automotive Engineers) nomenclatured "Full-Pressure" lubrication system.

GM/Chevrolet was a little more flexible/generous when using the term "full pressure".

So in the never ending journey to find a replacement engine I've located a complete early '54 235 with everything on it including the tranny. It has the water pump mounted in the right place for the '46 rather than the lower mounted one. And then I just found a "complete" 261 for a couple hundred more. The date code on it is July 20, 1954 and it appears to also have the higher mounted water pump. Both captains bars are there as are the additional water holes. It's been bored and stroked to a 304. It is currently apart but comes with a rebuilt 848 head and all the parts needed to put it back together. And, here's the clincher, it also comes with an additional 235 that was rebuilt but apparently had a bad rear main and is now apart again. I'm thinking this is worth a 4 hour drive to go pick them up. I've also located a rebuilt 848 head from someone else closer to me.

Joe