Mopar Mistake 'Not offering a 273 Commando HP II 'option'

[69 Cuda 440]

1965 thru 1967

The 273/235 Horsepower 'Commando' though a good little package was
without a doubt,,,,

Over-rated at a 235 HP Rating.

When compared to the;
* Chevrolet 283/220 HP
* Ford 289/225 HP

Could never understand why the 235 Horsepower rating. Of course years
later the NHRA rated the 273 to {220} Horsepower, and then again {210} HP, clearly more accurate numbers.

Chrysler, in their sometimes lack of effort with the small block - could
have and should have offered '2' versions of the 273 Commando.

The 'original' "273 Commando" should have been rated at 220 Horsepower.

But, a second "273 Commando HP II" {273/240 HP} should have been offered, with a step up in
A) Camshaft
B) Valve Springs
C) Carburetor
D) Intake

Could see a
A) .440 Lift /260* Duration 'Mechanical Camshaft'
B) #225 lb. Load-Rated Valve Springs
C) Carter AFB {600 CFM} Carburetor = {1 7/16" x 1 11/16"}
D) Aluminum Dual-Plane Intake

 

[toolmanmike]

That would have been cool for sure. I was disappointed to hear of the lower HP rating of the 4 barrel 273 but I'll bet the manufacturers didn't dyno anything back then. The little 273 has potential with the right parts and tune. I think the exhaust is the biggest downfall. If they would have built the bodies a inch or so wider, there would be room for better manifolds or easier to install headers. Mike

 

[69 Cuda 440]

Tool Man Mike,,,,,,

I just checked out the '273 Build' tread,,,,,,,

Muy Excellente'...........

Chrysler had originally stated that they couldn't put in 'dual exhaust' on the
1965 A-Body due to under-chassis restrictions. So they carried that philosphy
over into 1966 and 1967.

* Just a 'silly inch wider', would have made life much easier.

The 1966 and 1967 Models clearly should have had 'duals'.

And in late-1965 Chrysler Industrial and Marine, had 'the toys' to make a
higher performance 273 Commando.

They had something in the '273' called the '244 Marine', which featured a 'Camcraft
Camshaft'.

I'll see if I can dig up the information.

 

[WildCat]

I think the real problem with duals on 66/67 cars is the single strap and offset gas tank. The 68 & up have 2 straps front to rear and centered tank so both frame rails are open for the exhaust tubes on the rear.

Had to cut the j hook on my car to give room for the exhaust pipe.

Seems most of the time the companies were under rating HP but maybe in the case of the 273 it was overrated.

 

[cudavert]

I think that, just by design, with that 3.625 bore it put it at a slight disadvantage against the 283 (3.875" bore) and the 289 (4.00" bore). Bigger bore offers less shrouding of the valves. Do the 340 exhaust manifolds fit on a pre-'67 car?

 

[69 Cuda 440]

Back in early-1966,

There was a performance exhaust company in Jacksonville, Florida that had
offered a 'dual exhaust kit' for the A-Body Barracuda.

They did the installation in their shop, as they had a 'State-of-the-Art'
'pipe bender' and 'shorty' lightweight mufflers.

Piping, glass packs 'Cherry Bomb type' and tail pipes {1 7/8"}.

No chrome tips, just the standard ends.

 

[RedFish]

When building production engines they have to find a comfotable medium. I think they did what they could to their 273 to make it produce a little more hp without shortening its life span. The next step forward was called 318.
Try to remember this, the Dodge brothers started by building engines. They made their fortune selling these engines to Ford. They knew how to build an engine that would live a long life. Everyone else had to figure this out for themselves. Or maybe they didn't. Maybe they got more performance along with fewer miles.

 

[coffeedart67]

Somehat related to this thread. What is the reason for the offset gas tank?

 

[mvh]

It's not that the tank is offset, it's that the 67 side-to-side strap has the J-bolt only on one side, and it sticks out into the space the tailpipe would occupy.

I installed duals with 2.25" pipe from the mufflers back, and I just slipped some gas hose over the threads to keep it from banging against the tailpipe. But that's not something the factory would do.

Somehat related to this thread. What is the reason for the offset gas tank?

 

[ddartdude]

I think the 273 Commando HP II should have had the #11 cam that you are testing in the other thread and released it in 1967. It would have been a good replacement for the D/Dart engine and should have been released across platforms. I think it would have turned a few heads.

{#11} = .504 / .515 Lift ~ 288* / 288* Duration
Cam = Camcraft P820-Bx 'D-Dart' Optimal Race (1967 Model) (High RPM - High Horsepower)

 

[69 Cuda 440]

Alan,

That #11 Camshaft may have been a liitle too 'radical' for the street.

I was thinking more in line with a
A) Moderate-to-Bumpy - Lift and Duration Camshaft (ie; .440 Lift and 260* Duration)
B) Aluminum Intake
C) Carter AFB 600 CFM (1 17/16" x 1 11/16")

Could have been 'Factory Rated' at 240 Horsepower.

And put the original '273 Commando' in it's proper rating of 215-to-220 Horsepower.