Need help identifying an engine

I recently picked up a 1951 Fleetline that developed an engine knock over the weekend and I’m trying to figure out if it might have the original engine in it to decide whether I want to rebuild it or do a swap. The most comprehensive list of engine numbers I can find is from here: https://chevy.oldcarmanualproject.com/models/engine.htm#51eng, but it doesn’t have much on 235s from 1951, and the only markings that start with X (image below) are from ‘56 and should come with additional letters.

If it looks like this could be the original engine, I’m thinking it would make the most sense to rebuild it; but if not, any advice on what to swap it with is more than welcome (maybe a 350?)!

 

Did you look at numbers for 216’s?
A pic of the engine would help to differentiate between a 235 and 216, the 235’s I had used 4 perimeter valve cover bolts, the 216’s I’ve seen had 3? Maybe bolts in the top and centered down the valve cover.

 

The 499 on the cylinder head would be correct for a '51 235. Of course, 235s only came in Powerglide cars at that point.

 

You have some options.
1. Rebuild it.
You are going to have to find someone or some shop that knows Babbitt engines especially Stovebolt Chevys. Model A mechanics may offer some help as Model A bangers used poured Babbitt bearings.

The Chevrolet is really fascinating in how it oils. It’s a half pressurized half splash system. It has little dippers on the rod caps that dip into the oil and then sling this oil into tubes that lube the bearings.
Chevrolet made a template to help align or aim these tubes with the dippers. This needs to be done before the oil pan is installed.
A machinist or mechanic needs to know this.

The Babbitt bearing Stovebolt Chevy gets bad rap for performance.
The truth is they are a very reliable engine. Chevrolet out sold Ford starting about 1938? Ford did not out sell Chevrolet again until 1957.

The Chevrolet did not like to run at extremely high RPM for an extremely long time.

They had to be built for that.

California Bill Fisher has a series of book about Flathead and Stovebolt race engines.
If I remember right special attention was paid to the dippers, tubes and oiling system. They usually had 4.11 rear gears and topped out at 110+mph with about 150+ HP.

The little Stovebolt can be made to run but really in short bursts.
You can’t hop in one and go 70+ through 3 states. If you want to do that, get a 51 Ford or Oldsmobile that is if you are using a 1951 engine.

As far as the original engine; it is what it is and what it is is really neat.

2. Full pressure Full insert engines started in 1950 with the 235 Bel Air engine.
You may have a full pressure full insert engine. I’m not quite up on Chevys as I am Fords.
If it is a Babbitt engine. You they can be converted to full insert.
Most of my info may be concerning the earlier 216 and 235 so keep that in mind.

3.Replace it with a 1954 up full pressure “Blue Flame” 235.
Full pressure Full insert became standard starting in 1954.
A 1955 up 235 can be swapped in but it does require the use of the earlier fan and water pump.

4. SBC......
This really requires building the car. It means changing the rear axle transmission and modifications to the rear springs. It means doing away with the torque tube, clutch and master.....
Putting a V8 in one of these is a big deal.

The simplest to do.....
Replace with another Stovebolt. (Sometimes these can be found rebuilt and ready to go)

Rebuild yours.

Replace with a 1955-62 235.

 

you need to move the camera down just a bit, and maybe to the rear....there is a machined pad at the base of the distributor, which has the engine number stamped in it. Also, a bit further back, partly obscured by the starter motor, you should be able to find the block casting number and casting date code.

If you find them, we can help figure out more completely what engine you have. The head casting number does make it look like it could be an original Powerglide equipped engine...let us know what transmission it has, also.

 

Thanks so much everyone, this is all very helpful. It has a power glide transmission, I’ve included two pictures I have from the front and I’ll try to get more as soon as I can. The weird picture above is the casting stamp from the passenger side center, I’ll see what else I can locate.

 

A 1951 235 will still have cast iron pistons and babbitted rods. One of the biggest favors you could do for it is replace the stock pistons with aluminum replacements; it'll be much less stressful on the rod bearings. Federal Mogul used to convert the stock rods for use with special insert bearings, but N.O.S. babbit rods are still quite plentiful, and not difficult to find.

 

Here are some better pictures of the engine and the actual engine code (thanks for the help confirming I didn’t have the right number), it just took a bit of scraping and cleaning to find. This looks a lot more like what I expected to see from an original engine!

 

J is 51, A is passenger car, D is 235 (for powerglide), as best I can tell.

The casting date, hiding on the block near the starter, should confirm the year. And the casting number (and the partial side cover) should confirm the displacement.