Has anyone ever built a 318/340/360 to look like a 273??

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Mike Correll

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I have a 66 Barracuda Formula S 4 spd car with the Commando 273.

The 273 is getting tired, and I’ve heard that they are difficult/expensive to rebuild with a decent amount of horsepower.

I think it would be easier to rebuild another LA small block, 318/340/360 to put out some more serious horsepower. The goal would be to build one of these motors to put out a higher amount of HP than the stock 273, but keep it looking like a mostly stock Commando 273. Basically a sleeper.

For the sake of originality, I’d like to be able to keep my Commando 273 air cleaner and the finned valve covers to keep it looking original.

I’m sure it’s been done before but I’m looking for any kind of advice I can get on a build like this. I’m attaching some pics of the car for your enjoyment. Thanks!

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273 air cleaner, Commando valve covers, Offy single plane intake, paint it Red...looks like a 273
 
All the LA blocks are basically the same. Rebuilding any of them stock cost about the same. Once you add performance components they all get more expensive. 65'
 
Its not really an expense concern, its the limitations of the 273. Bore size and valve size limitations.
 
Unless I'm mistaken you could pull out the 273, bolt in the 318, and all of the exterior ( oil pan, valve covers, 4bbl intake, timing cover, water pump, etc) will bolt right on.

As others have said paint it red and the only way anyone would know is the casting number and the number stamped in the front of the block on the driver's side
 
Yup my daily winter beater is a 318 incognito.
 
My 273 was tired also and I decided to go with the 5.9 Magnum and keep the V-belt front. Had planned to keep the valve covers and air cleaner but, I've decided to sell the 273 Commando and transmission whole. It just didn't feel right breaking up the 273. Plus, with the Air Gap I would have to use a shorter air filter in the Commando air cleaner to clear the hood. Thinking I'll go Mopar Performance if I can find them.

Funny thing is, I haven't sold it yet and I already miss the 273.:(

Here's a picture of the 5.9.
IMG_20200319_224205.jpg
 
Getting ready to do just that. Have a 273 commando top end to put on a rebuilt 318 with 302 heads. Ha.ve a 64 dart gt to put it in
 
Everything 360 bolts to a 273, cept the balancer (and convertor, but you can fix that)
 
318 stroker and change the casting numbers on the block with devcon b 4 paint
or 360 unless someone looks under the headers at the motor mount it would pass a casual visua late roller motor would be nice
late magnum with la heads and valve covers
most likely would not even need a rebuild
 
Back in 67, Dover AFB, my (not so stock) 273, 65 Barracuda, was accused of being a 318, by some dude with one of those "new Camaros." Hey it was his idea to make the challenge, not my fault he didn't like the outcome.
 
I have a 66 Barracuda Formula S 4 spd car with the Commando 273.

The 273 is getting tired, and I’ve heard that they are difficult/expensive to rebuild with a decent amount of horsepower.

I think it would be easier to rebuild another LA small block, 318/340/360 to put out some more serious horsepower. The goal would be to build one of these motors to put out a higher amount of HP than the stock 273, but keep it looking like a mostly stock Commando 273. Basically a sleeper.

For the sake of originality, I’d like to be able to keep my Commando 273 air cleaner and the finned valve covers to keep it looking original.

I’m sure it’s been done before but I’m looking for any kind of advice I can get on a build like this. I’m attaching some pics of the car for your enjoyment. Thanks!

View attachment 1715489761

View attachment 1715489762

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I like the sign on your garage. A guy I work with made mine.

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273's use all the same parts as any small block, except pistons. They have forged cranks and typically the crank does not need turning, just a polish. They run mechanical cams. The 2 barrel pistons are typically .020 in the hole. 4 barrel pistons have a dome. The heads are closed chambers and flow better than any 318 head as cast. With a good rebuild a 273 with 2 barrel pistons will make almost the same HP as a "back in the day" 340.

However, if you wanted to put a larger engine in place of a 273, Use the 340/360 heads, add the extra expense of headers. There are base plates that have the standard large opening to allow the use of the Commando air cleaner. Use an Offenhouser single plane intake and a 750 cfm AVS. Use the Commando valve covers. Now you will easily over power any tires you can fit on the back of a 66 Barracuda.
 
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340/360 open chamber heads will lower the compression ratio. The original 273 Commando heads are closed chamber. 65'
 
273's use all the same parts as any small block, except pistons. They have forged cranks and typically the crank does not need turning, just a polish. They run mechanical cams. The pistons are typically .020 in the hole. The heads are closed chambers and flow better than any 318 head as cast. With a good rebuild they make almost the same HP as a "back in the day" 340.

However, if you wanted to put a larger engine in place of a 273, Use the 340/360 heads, add the extra expense of headers. There are base plates that have the standard large opening to allow the use of the Commando air cleaner. Use an Offenhouser single plane intake and a 750 cfm AVS. Use the Commando valve covers. Now you will easily over power any tires you can fit on the back of a 66 Barracuda.

2 barrel engine pistons are in the hole. Charger/Commando engines fill up those closed chambers a bit. I don't think I ever measured. :BangHead:

clutch kit 001.jpg
 
340/360 open chamber heads will lower the compression ratio. The original 273 Commando heads are closed chamber. 65'

I would not give up a Commando motor. The second paragraph in my post was for a larger engine, starting with 360/340 heads. 360/340 heads are about 8cc larger than 273 heads, about a .040 cut. Then you have to worry about intake valve hitting the block on a 273 only. I have done it, but you must measure everything and assemble carefully. But I was not advocating putting the 360/340 heads on the 273.
 
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