1951 Chevrolet engine swap

[crazycars]

Gentlemen, I am looking for a suitable engine for my 1951 Chevy Styline  which has a 223 engine.  Any of you have any experience with this? I've seen various writings about using a similar truck engine or a 250 but I would like to have as easy an installation as possible and minimize fabricating and changing parts.  All answers greatly appreciated.

[JohnS25]

I believe you will want to find a 235ci Chevy, it is virtually a bolt in and only an experienced Chevrolet guy will know the difference

 

John

Edited June 18, 2023 by JohnS25 (see edit history)

[Bloo]

Is this Canadian? I believe the 224(223?) was a Canadian overbored Chevrolet 216 intended for a Canadian Pontiac. Is this what you have?

 

A US 1951 Chevrolet would normally have a 216 if it is a stick and a 235 if it is a Powerglide. The 235 in this case is not like the later ones. It is more similar to a 216, having cast babbitt bearings and "low pressure" oiling.

 

The popular thing to do is to put in a later 235. Sustained speeds of over 50MPH were bad (depending on who you ask) on the old "low pressure" engines once they got a little loose. Rod bearing failures were reported.

 

As far as I know, the 99% bolt in engine is a 1954 235, or a 1953 235 from a car with a Powerglide, or a 1954 261 from a big truck. For 1955 there were changes in the engine that make it a little more difficult, but aftermarket parts are available to make it easier, for instance a plate to mount an earlier water pump on a 1955 or later 235 or 261. There are probably other things that need to change, but this conversion is done so often you can find the parts. They kept making 235s all the way until 1962. The Stovebolt.com forum probably has the best information about all this.

 

The 230/250 is a better engine by far on paper. In practice, I don't like it much. Also there is absolutely nothing about it that directly bolts to a pre-1955 Chevrolet. It is about the same general size and shape though, so you could stuff one in there if you want to. Many have. It's not near as common as the easy 235 swap though.

[Oldtech]

You can also put a Canadian Pontiac 261 in there. Very torquey engine.  If you are in the U.S. they had them in trucks only. Okay, but the 57-62 Pontiac is the best.  All you have to do is mess with the water pump. You will have to shorten the shaft an inch and press the flange down the inch and find a different pulley. There is a Ford one that works. 289 maybe

[Rusty_OToole]

Bloo gave a good answer. The 216, 235 and 261 cu in six will bolt up to your bellhousing and transmission. 1953 (Powerglide) and 1954 (all) and newer, have the preferred insert bearings and full pressure oiling system. The best or most powerful, would be the 261 cu in used in large Chev trucks 1954 - 62 and Canadian Pontiacs 1955 -62.

 

Here is the swap in detail from Inliners International. I would add, if you want to go to 12volts, you can use the 55 up ring gear and starter, they are different from the 6 volt with finer teeth.

 

https://inlinersinternational.org/swapping-stovebolts/

[Rusty_OToole]

The newer engine used to be a popular swap when good used engines were available. Now, the newest is over 60 years old. Check your engine number, you may already have a newer engine. In any case it may be easier and cheaper to rebuild your old engine if the rod is not sticking thru the block.

[crazycars]

Thanks, Rusty. You always have great answers! Appreciate it!!

[Rusty Heaps]

While not as common as in days past, the 235 is still relatively inexpensive and they do show up for sale regularly.  Usually when someone decides to install a V-8 the engine goes on the market. Should you do the swap don’t pull the front motor mount plate from the 235 to install the plate from the 216, just drill the holes for the mounts. There’s a lot more involved in the plate swap which includes pulling the cam shaft. I did the swap on my ‘46 coupe, and intend to do likewise on my ‘50 Fleetline eventually ( the 216 is performing well for the time being but I would like to attain highway speeds). I’m also of the belief that the ‘58/‘62 engine is mechanically superior to older ones. Best of luck with your project. 

[Oldtech]

I've not heard of a 223 Chevy in Canada. they were all 216 until the powerglide came then they had a splasher 235 for a couple of years with the PG. Our Pontiacs used the flathead til 54, then the 261. 

I did this swap on my 47 Chevy. The 235 is by far the most common and you should be able to find a late model one at a reasonable price. The Chevy salesmen used to tell us the 235 was almost as powerful as the 261 but a well tuned 261 is a torque engine and will pull like an 8 until 60 or 70 mph. (then the 8 wins). 

[Rusty_OToole]

I think if I bought a random 235 or 261 I would take the head off and the pan off to inspect the cylinders, bearings and valves. If it checked out good would touch up the valves install new gaskets and be satisfied. If necessary would hone the cylinders put in rings and bearings and do the valves. Worst case, badly worn engine would need to be rebored and completely rebuilt. I don't know what this would cost but should be reasonable as parts are plentiful and they are not a difficult or complicated engine. And you would have the satisfaction of knowing your engine was in perfect shape and good for at least 50,000 miles.

 

As it happens I have a 261 from a 62 Pontiac. It only has 50,000 gentle miles but sat in a field for 40 years and is frozen up, I expect to do a complete rebuild before it is any good.

[Frank DuVal]

FYI, I was told years ago the 235 blocks can be bored 1/8". 😁

 

Although the largest pistons I can find at Rock Auto are .080" over. That's still large!

[Oldtech]

As a note: you can use a 235 head on a 261 if you drill the steam holes as the cylinders are siamesed on the 261 to get the 3 3/4 bore. Valves are the same.