Stirring up a hornets nest

-
That's good pishta. I love the comments and opinions expressed here. There are plenty of those.
 
... As for the little 273.. Im a user and a current owner (273/2) and past owner of a 273-4. My 273-4 spun a bearing so I swapped everything 273-4 sans pistons and crank over to a 318 short block. Even @ low compression, that 318 trounced the 273/4 performance wise.
The 273/4 had 235 HP @ 5200/260 tq at 4000 while the 2bbl had 180 HP @ 1800/ 260 tq at 1600. The "no respect" '68 318 workhorse had 230 HP at 4400 and 340 tq at 2400, all at flywheel..and that was a 2bbl! . Does the smaller 273 rev faster? I think the /2 pistons are close in weight with the /4's a little heavier.
So the guys look at your 273 and tell you to upgrade. Lie to them and tell them its a stroked 340 to 422cid with 273 badges. Just dont try and back that up.

My son has an original 318 in his 73 Dart. 273 4 barrel, intake, small MP hydraulic cam, and good DC quick curve distributor. The is no chance that motor could ever take my 273 Commando. As for a stoked 340, I already make too much power for an early Barracuda, and I'm not into low end torque. I don't even like 360's. Power wise the 273 Commando is perfect for me. If I want more than a 340 in a second generation, I'll go BB. Stock stroked, better flowing heads, and pretty much for nothing except for some headers and mounts.
 
It is so wet here. Wettest May in over 100 years in central north Carolina. I would really prefer to do them outside,
 
Me, I've daydreamed about getting hold of one of the Argentinian big "906" Slant-6 blocks that'll support a bigger bore than the regular items, and bore it to 3.745". That would yield 273.35 cubic inches, then I'd put a Hyper-Pak on it and go around telling people—truthfully—that it's got a 273-4bbl.
 
my take is if you have a good 273 use it for this type of fun car. great engines... if no engine, take a 360 and make it look just like the 273 and lie to those that ask what it is, and too lazy to check the # on the block! ha
 
I'll be happy to finish mine and have some fun. I bet my tires last longer than the other guys anyway
 
Me, I've daydreamed about getting hold of one of the Argentinian big "906" Slant-6 blocks that'll support a bigger bore than the regular items, and bore it to 3.745". That would yield 273.35 cubic inches, then I'd put a Hyper-Pak on it and go around telling people—truthfully—that it's got a 273-4bbl.
It's got a different sound but 500 ft.lb. under the hood. Lol
 
Can you imagine when I put the new HIPO exhaust on mine. I think it will be awesome. When I take the dual exhaust off and have the single resonator, these guys may flip. It's all good though, it's what I want to do.
 
My son has an original 318 in his 73 Dart. 273 4 barrel, intake, small MP hydraulic cam, and good DC quick curve distributor. The is no chance that motor could ever take my 273 Commando...
How? Look at the specs: its the same stroke but bored 15% bigger. 10.5:1 compared to 8:1 brought the HP up but look at the torque of a 318 compared to a 273 of any flavor sans D code. Im telling you, that "S" was a different car with that 318 block. I even used the 273/4 cam that was mismatched to the compression of the teen. Your results may vary..
 
Can you imagine when I put the new HIPO exhaust on mine. I think it will be awesome. When I take the dual exhaust off and have the single resonator, these guys may flip. It's all good though, it's what I want to do.
The Hipo exhaust is nice. I used the Accurite LTD set up. sorry for the poor video.

 
I have the accurate setup as well. Went without the resonator a regular muffler though with a turn down. Fits nice.
 
I have the accurate setup as well. Went without the resonator a regular muffler though with a turn down. Fits nice.

Sounds really good! The only reason I did the resonator is for the tip.
 
If I can ever have the time and the weather will clear up, if, if, if. Maybe this week will improve
hoping. Thanks for the videos. Love the sound
 
Dare to be different, keep the 273..........the jerk who said jerk the 273 should learn some manors.
 
... Your results may vary..
I think your last thought says it. A 273 was a High Performance engine from the beginning. 318's had to wait till the 80's. All my 273's were balanced and blueprinted. That means every chamber was equalized to within .2 of a cc. TDC was found and marked. Cam was degreed in. Bores were honed with torque plates and mains torqued. They were built when you could readily get 10.5 forged pistons. Theoretical size and horsepower numbers don't add up. A good 273 will hold it's own against anything near it's size and more. A 318 built the same way should be faster, but not by much. But it takes the whole package and attention to detail.
 
Last edited:
Don't think I don't like 318's because I do. When I did a 318, I jumped right to the 340 / 360 heads along with a 340 intake and carb. 340 horsepower on a budget.
 
Somebody is comparing apples to oranges.The early LA 318s when rated the same way as the 273s, were rated at 230hp(2bbls, remember), and 340 ftlbs at 2400. The 340s when similarly rated, were 275 (4bbl now), and 340 at 3400. Forget the alleged "fudged" 340 hp numbers for a sec and look at the torques. If you understand the hp to TQ relationship, this tends to indicate that the lowly 318 has more torque than the mighty 340 at every point below 2400, and possibly a long way up the curve towards 3400.
When the new ratings came out, in about72, the engines were rated differently, but were very nearly identical engines. So please don't confuse 230 hp LA-teeners to 180 horse LAteeners.
Now I don't have figures for the mighty 273-4bbl, but you don't have to be a rocket-scientist to extrapolate the numbers backwards.
Now as to fudging? who knows what's right. Or even if anything was right!
Now I know you 273 guys love your mighty engines.....................but please don't hate me.
 
Last edited:
I like to study the NHRA blueprint spec sheet for stock and superstock classes and their factoring system.
They factored
the 273 -4bbl at 235hp, The 2bbls at 180/190
all 318s,2 or 4bbls, from 67 to76 as having 225 to 230hp
the HC340-4s at 300/310hp, the LC 340-4s at 270
the HC340TQ at 325hp which is about the same as the 6bbls
the HC360-4s at 270 to 290
the LC360-4s at 250 to 265

Now compare th 273-2s to the teeners. They had the same cams, the same ports and valves and about the same C/Rs. So basically the 2bbl-teener is a big-bore 273-2, with an extra 40 to 50 hp. And a mountain of torque.If you do the math; thats 1 hp for each cubic inch. You see where this is going, right?
Well if you pump up the C/R of the lowly teener to match the 273, and give it the 273 cam, what might you expect. Ima gonna guess the same extra 45 hp. So doing that math, the teener becomes 280 hp.
So now, lets work the 340-4bbl backwards. at 22 cubes bigger,and 300hp, I'd expect no less than 22 hp difference to that HC teener, when the 340 heads and cam go into it. Doing the math, I'd be expecting 300 less 22 =278
So now we have a problem. You can't have a HC-teener, with a 273 cam, and rinky-dink heads,equal a HC-Teener with a 340 cam and heads. So obviously there is some fudging going on in the numbers.
So I did a little digging, and this is what I found. The HC273-4 is factored at .86hp/cid, the teener at just.72hp/cid,the 340-4 at .88hp/cid, and the 360-4 at .79hp/cid
What'can we learn from this?
What I see is HC engines make quite a bit more specific output than LCs and obviously, 4bbls make more than 2bbs.
So what can one really expect from a HC-318-4 ? Ima guessing about .87 hp; and that math is 277hp
So while you're there, how 'bout a HC360-4? Ima guessing .89 hp/cid or 320hp.

So lets line the horsepowers up; 235--277--300--320
And let's look at the differences.......42---22----20
Now if I just had torque numbers to screw around with................
 
Last edited:
Great information. Thanks for sharing the horse power ratings. I had posted earlier that a friend who worked for Chrysler back in the day had told me the 273 commando was rated on the low side because the insurance companies charged a higher premium based on the ratings. I'm not really concerned about the ratings. I'm quite happy with my formula S. Once I finish the world on the car and have it on the street I will be even happier.
 
for the sake of conversation, would not the " feel of your pants" power, which we are talking here, NOT racing...... would it not be pretty similar between all these SB. the difference we would get ( assuming the same condition, similar compressions, cam of each engine), be in rear gears, distributor curve, tune of carb. and perhaps the ratios of the trans?????

I see a lot of all this, is which group you fall into???. the old school mindset of building a good running fun to drive hotrod for as fewer $$ as possible?.... or the I have $$ and I want all the streetable power I can get, and can afford the best parts $$$$ and a stroker etc...????????
 
-
Back
Top