273/4 -318 debate

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toolmanmike said:
"All cranks were forged" is a encompassing statement. Maybe not. I had always heard that Mopar used forged cranks up to 72 in the small blocks. I don't know about the slants and big blocks without looking it up.
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Bought a '72 340 hoping to get a forged crank but she was cast sure enough...
 
CHROME OGRE 313 said:
ALL CHRYSLER CRANKS WERE FORGED BEFORE 74 ... EVEN SLANT SIXES , SOME OF YOU GUYS MUST BE CLOSET CHEVYHEADS...
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I don't get it. What has that got to do with a 100 horse shot?,, as stated in post 41, to which I responded in 42.

5 of your 7 posts are right on these last two pages, and all are yelling and argumentative if even related. Are you Ok? Do you need help getting off the meds? Or do you just need a new keyboard and some sleep?
 
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SORRY , I WAS TRYING TO REPLY TO POST #1... AND IM NOT YELLING , I USE CAPLOCKS SO I CAN READ WHAT IM TYPING ....
 
CHROME OGRE 313 said:
SORRY , I WAS TRYING TO REPLY TO POST #1... AND IM NOT YELLING , I USE CAPLOCKS SO I CAN READ WHAT IM TYPING ....
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At the top of the page inside the address bar is a little oval just to the right of center. Press Ctrl and the + sign, at the same time and watch the number in the circle telling you how much you have magnified the page. Just enlarge the page until you find it comfortable.THEN TURN OFF THE ANGRY CAP LOCK. You may have to readjust the magnifier on different forums.
If you find yourself punching it up continuously, you can go into your program and punch it up there semi-permanently. Tou can still use the Ctrl+ feature, it will just start from the newly internally set size.
You can find the program by calling up the Desktop, and clicking on the circle with the 4-colored flags in it. Then click on "control panel" the "appearance and personalization", then"display", and finally "screen resolution". I have mine set to 125% and run it there.And I run my magnifier at 67% most of the time.

When replying to a particular post, go down to the Quote/reply box on the bottom right of the post in question and click on reply. This will transfer the post in question into your new reply box, where you can review it and manipulate it with the tools across the top of the reply box. In this way there can be no confusion as to which post you are referencing..... and you can win even more friends.
Try it and win friends.

Ps sorry about your vision problem, welcome to the crowd, easy on the meds, and at age 65,I know all about lack of sleep, and tight shorts under the covers.
 
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Just to add my two bits worth. In the spring of '66 I factory ordered a new Formula S Cuda. It was a black on black with the broad racing stripe in red over the car. I got a HiPo 273 as standard of course and added a four speed with 3.55 SureGrip and manual disc brakes. The best time that I ever turned at Kent Pacific Drag Strip was 15.26 @ 92mph. At the line I would rev to 2500 and drop the clutch. This resulted in wheel spin, but no bog and gave me the best results with the original Blue Streak tires. As summer progressed I became somewhat dissapointed in the lack of go with the HiPo 273. The only change I made was to remove the main muffler and have only the rear resonator, sure did sound good though. My personal feeling then and now is that Mother Mopar should not have done the HiPo 273 as it was just too small. They eventually fixed that two years later with the 340 ! which I have now and love in a '69. In December '66 I traded the Formula S in on a '66 Satellite Street Hemi and that was a whole nother animal.
 
For those that forgot. here is post #1 for reference,lol. click on expand.
pishta said:
Were having a discussion on the merits of the 273-4 engine compared to the 318-2 of the following years, sometimes even the same year. Sure the 273-4 was a hot motor back in 65 when it was the best thing between the fenders of the early A's but you just can't deny that a 20% larger motor is going to make a difference. Performance test are all over the board, depending if the dufus can drive or if the dyno is set up properly, yadda yadda...but I found a site that has a lot of info on cars in general and has generated graphs (from factory data) on performance specs. So I tried to match 2 like cars (in weight, gear and transmissions) with our 273-4 and the 'new' 318-2. Results? Well, I think it would ultimately come down to the reaction time between these 2 motors as they are pretty close. You can see the shift points are higher on the smaller higher winding 273 and the torque advantage goes to the 318 down low. Theoretical top speed goes to the high winding 273 due to the cam profile and possible higher RPM potential of its heavier valve springs and forged crank.

1965 273-4 Barracuda
reference weights: shipping weight 3029 lbs base curb weight: test weight 1430 kg / 3152 lbs
how fast is this car ? top speed: 126 mph (©theoretical);
accelerations: 0- 60 mph 6.9© s; 0- 100 km/h 7.3© s (simulation ©automobile-catalog.com); 1/4 mile drag time (402 m) 15.6
View attachment 1715247101







1968 318-2 Barracuda
reference weights: shipping weight 1363 kg / 3005 lbs base curb weight: 1430 kg / 3152 lbs
how fast is this car ? top speed: 178 km/h (111 mph) (©theoretical);
accelerations: 0- 60 mph 6.8© s; 0- 100 km/h 7.3© s (simulation ©automobile-catalog.com); 1/4 mile drag time (402 m) 15.4© s

View attachment 1715247102



overlaid


View attachment 1715247103

<<<lower 75 from tq curve points to align 5250rpm intersection>>>
<<<the tq graph should start at 100 so the data points align SAE>>>

and the overlay of the HP/torque curves from factory data. increased displacement really shows in the torque curve but the smaller 273 can hold its HP peak longer. This is due to camshaft differences. Put a similar cam in a 318 and its curve would change.



Bottom line: in a 1/4 mile race all things being somewhat stock on these 2 cars, the 318 would edge it by .2 seconds..theoretically. Now on the highway having some fun with your buddy, the 273 would probably walk away after 4500 RPM. Now put the 4bbl cam in the 318 and it would probably be a 20% increase across the board on the 318 data. To say the 273-4 would walk a 318-2 in a drag race is not supported in this data. All data is from blueprint specs and we all know how well those are kept in production, especially compression ratios.
Food for thought...or to fling?
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toolmanmike said:
"All cranks were forged" is a encompassing statement. Maybe not. I had always heard that Mopar used forged cranks up to 72 in the small blocks. I don't know about the slants and big blocks without looking it up.
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The lucky winners for cast cranks were 360’s and 400’s, followed by 318s and 340s and about everything else in 1973, except maybe HP2 and industrial engines. I have heard that heavy duty truck 318s used forged cranks up to1976 but unless I take it apart myself I take nothing for granted past 1970! I have even heard that late 1971 383s came with cast cranks to test the cast crank platform in big blocks...
 
OK guys, listen up. I have a couple Mopar small block books and this is what they say about small block cranks:


"The A engine cast crank was introduced with the 71 360 engine. The 360 has never used anything but a cast crank in production. By 1975, all A engines used a cast crank. The automatic transmission 340 engines got one in 72' however the manual transmission cars still used a forged crank until the end of 73'. Cast cranks made their first appearance in the 318 but they required no external balance, which makes them harder to identify. By the end of 74' all production forged crankshafts were gone". (Larry Shepard-How to Hot Rod Small Block Mopar engines)
It would be interesting as to whether some forged cranks were used in truck, marine, or industrial applications. A possibility.


"All production small block crankshafts made since mid 1972 have been cast cranks. LA and Magnum production crankshafts are very similar and can be interchanged as long as the proper rear main oil seal and pilot bearing are used. Early 273,318, and 340 engines used a production-forged crankshaft." Jim Szilagyi (Dodge Motorsports Engineering Dept.) How to Build Big Inch Mopar Small Blocks.

There you have it. A bit more specific info. It looks like 72-74 were the phase out years for the forged crank depending on engine and application. tmm
 
A buddy of mine ran across a 66 D-Dart with the hi-po 273 in it. The seller thought it had a rod or main bearing knock. The guy was asking $600 for it. Ken took it home and adjusted the valves. The seller didn't know it had a solid lifter cam from the factory.
 
Commando 273 engines were 4 barrel engines and had a number of special HP parts. The 318 was a 2 barrel work horse that had the best Warrantee record of any American V-8. Not being theoretical, I actually ran a 66 Formula S 4 speed Barracuda on the street. Raced from a stop more than a few stock 318 2 barrels. No chance, not even close. Nothing anywhere it's size was it's match, even with 100K on the speedometer. A lot of cars could get the jump on me, but once she hit 3,000 rpm she took off and I'd pass them like they were standing still. Having a 1,000+ higher rpm range is also a big factor. A friend of mine has a 67 4 speed Formula S Fastback and had his 273 dyno'd. With all the Commando good stuff and 2 barrel pistons, a small Isky E-4 cam, and a 600 Edelbrock carb the little 273 made 260+ hp at 5,500.

In general If you are building any wedge engine, you should be able to get 1 hp per cubic inch and torque as well. A good 273 will move a 65 Cuda very well and get 20+ mpg. 66 Cuda's were lighter than the 64 and 65. A High Performance 273 likes rpm and will easily run to 6,000 to 7,000 rpm with stock heads. I had a 64, 4 speed Cuda as a daily driver for decades. Loved that car. Here are some stock hp numbers from one of the Chrysler Racing manual. Notice that a 318 2 barrel does not make any where near 230 hp. Depending on what you have, all engines are similar in cost to build. What do you have available? What do you really want the car to do? Start there.

Stock hp Estimates.JPG


Stock Weight Estimates.JPG


MP Engines.JPG
 
Hang on if you believe the 318 numbers , do you also believe all the other numbers?..... like the 4bbl 360 numbers, or the 390/410 hemi?
This argument is so old, and so rotten,..............

The 74 4bbl 360 had all the 340 stuff on it from the previous year. All of it including the same advertised compression ratio. So now, there it sits blazing out in 245 hp glory, while the 340 sits at minimum 275. How does 20 cubes less make 30 hp more, wearing all the same parts. Com'on;. that chart stinks so bad.....
Not to mention the sucked out Hemi numbers

Or the fudged 318 numbers. How does a 318 with 45 cubes more than the 273 make 50hp less with just the loss of 1 point of compression and a bit of lift and two tiny secondaries?
I mean I ain't the brightest candle in the package, but I can tell there is something fishy going on there.

Or how about the 440 numbers ? 40 hp from adding a 2bbl over a TQ? I don't think so. Going by the same ancient source How much power was given to the 340 6pack over the TQ? Was it 10 or 15 hp I forget. And now the 440 is claiming 40hp from a 2bbl with the same cam and heads?
Crimminy I need to put a 6-pack on my lawnmower.
 
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motorpirate said:
The better question is, does it matter?
Are Mopar cast cranks prone to falure?
I'm thinking not....
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There seemed to be a lot of misinformation a few posts back. That's why I posted what I had found. Nothing more, nothing less.
 
318willrun said:
Had a '72 340 with a cast crank. '73 340's would be cast. Dude! your striking out on every post - this stuff isn't opinions, it's facts!!! LOL
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My '72 motor is forged. They started out with a steel crank, but changed sometime mid year. Most LA 318's were cast crank.
 
"The 74 4bbl 360 had all the 340 stuff on it from the previous year. All of it including the same advertised compression ratio. So now, there it sits blazing out in 245 hp glory, while the 340 sits at minimum 275. How does 20 cubes less make 30 hp more, wearing all the same parts."

'72 and '73 340's compression was dropped to 8.5-1 and rated at 240 HP. 5 less than the HP 360's
 
66fs said:
... A friend of mine has a 67 4 speed Formula S Fastback and had his 273 dyno'd. With all the Commando good stuff and 2 barrel pistons, a small Isky E-4 cam, and a 600 Edelbrock carb the little 273 made 260+ hp at 5,500.
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Thats my point exactly: "with all the commando stuff ( The intake, advance curve and springs... whats left?) and 2bbl pistons...260+HP at 5500" imagine all that motors commando stuff (and other parts) on a ~18% bigger 318 short block (like I had, night and day with the 318 block). Like I said on the other thread, there aint much a 273-4 can do that a 318 cant do better.
 
'73red-duster said:
"The 74 4bbl 360 had all the 340 stuff on it from the previous year. All of it including the same advertised compression ratio. So now, there it sits blazing out in 245 hp glory, while the 340 sits at minimum 275. How does 20 cubes less make 30 hp more, wearing all the same parts."

'72 and '73 340's compression was dropped to 8.5-1 and rated at 240 HP. 5 less than the HP 360's
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You know it!
But the page don't say that
 
pishta said:
Thats my point exactly: "with all the commando stuff ( The intake, advance curve and springs... whats left?) and 2bbl pistons...260+HP at 5500" imagine all that motors commando stuff (and other parts) on a ~18% bigger 318 short block (like I had, night and day with the 318 block). Like I said on the other thread, there aint much a 273-4 can do that a 318 cant do better.
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I like that,
even an 8/1 318 with nothing but a TQ on a small-port intake,and free-flowing exhaust is surprisingly powerful in a lightweight-A. Even in my porky 2nd gen. with the 1st gen trans and 3.55s.
And I like to say the same thing about 360s vs 340s, in streeters. The extra torque a 360 makes, combo for combo, is never a PITA. If it was there would be no market for strokers.
But I gotta say this; I have sucked a lotta mpgs out out of 273s,especially in 7/8/9 Darts. That 273 is 4.47 liters. But it can run mpg numbers of engines down to nearly half it's size in non-injected more modern cars; what's up with that?lol.
 
pishta said:
Thats my point exactly: "with all the commando stuff ( The intake, advance curve and springs... whats left?) and 2bbl pistons...260+HP at 5500" imagine all that motors commando stuff (and other parts) on a ~18% bigger 318 short block (like I had, night and day with the 318 block). Like I said on the other thread, there aint much a 273-4 can do that a 318 cant do better.
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That is what I have been telling you all along. You keep saying a 318 2bl will run with a Commando. My cousin thought the same and I proved it to him twice, happened like I said above, back in the day. I have no idea how your Commando was a dog, mine was not. The only point here is, you don't need a 318, 340, or a 360 to go fast. The 273 in the 64 4speed Cuda had the same power to weight ratio as a stock 383 4 speed Road Runner. It was a stock 2 barrel for about a month. And that was with a Holley 600 and a 284 duration cam. At it's best configuration it would blow that combination away. That little 273 would run anything. Looked at trading the 64 Cuda for a 360 Volare and passed since it was not as fast as the 64 Cuda. I took the money and had my seats recovered in leather. I used to build 318's for other people, but I kept my 64 273. With 4.10 gears it would fry the tires all the way thru 1st and halfway thru 2nd. With highway gears you could wind it up to 100mph in 3rd gear and shift into 4th. With 2.76 gears it would get mid 20's mpg on a road trip. This is all from a daily driven, always up for a race, drive anywhere, street car with 200,000 and 300,000 miles on them. I've said it before, I could have any engine I wanted. I am running 2 273's in a 66 and 67 Cuda and a 383 68 Formula S. You can make anything go fast with any Mopar engine if you use your head and can tune a combination. Yours may not be fast but, it does not mean mine is not.
 
I’ve got no horsepower or torque numbers, but a 273-4 powers this heavy SOB. She’s no slouch either.

D4DB3B84-00F6-48D2-9CDC-C9E449C70825.jpeg
 
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