What would I gain from a 4bbl on a 273?

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Flatlander

Flatlander

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My 66 dart gt has a stock 273 in it and I'm planning on dual exhausts this spring, along with electronic ignition. Would I gain much by also installing a 4bbl carb or is it a waste of time and money? I don't want to stray too far from stock.

Also, what is the relationship between horsepower and torque? I've noticed early Buicks carried a high torque rating relative to hp. Is it possible to squeeze more torque out of this motor?
 
Hey Flatlander;

It will be a nice upgrade, mostly in the HP department. I can not say for sure what the increase will be, but I do think all the exhaust work and a 4bbl will be nice. I tend to do the same to all my mondaine cars to spice them up. It is very satisfying.
(sp, all over)
On the HP to torque thing you ask about, torque, based on the engine configuration alone and nothing else is more readily avaliable with a longer stroke engine. You can see this in a 383 MoPar vs. a stoked SBC from a 350 to a 383. The Chevy engine with a longer stroke makes more torque in the low RPM band than the short stroke MoPar 383. Then the HP that comes in with the higher RPM's tends to be favored with the MoPar.

Your 273 is a short stroke engine. A few things that can help in the torque producing area would be dual exhaust with or without headers. Headers a plus. Change of cam. I would call up Comp or Crane for help and ask about customizing a cam to enhance torque in a small engine.
Now that your going to a 4bbl. , a small one, like a 500 cfm unit is more than enuff for moderate engines and small ones as well. Going to a larger one will weaken the snappy response and hinder good air and fuel flow for good torque making mixtures.

Some head work can enhance low lift cylinder filling. (This an a cam designed for this thought train) By addressing low lift cams and enhancing the cylinder head to take advantage of this all, you can help fill up the cylinder with more air and fuel.
Now that theres more in the cylinder, the result is a more powerful charge and bang.
 
Try to biuld it like the Commande/charger engine. 4 bbl, more cam, hipo piston and better exhaust. If you ad headers your lokking at 250-260 horses
 
Carefullly done, marginal. Carelessly done, huge. He he he he
 
I would say do the exhaust first before you worry about the 4bbl. And I personally probably wouldn't do the 4bbl until you had a bigger cam.
 
Thanks everyone, esp. Rumblefish. I'd often wondered about the torque.

Would anything have to be done to the throttle linkage to accomodate a 4v carb.? Also, what kind of carb would be good to use, reman. stock or aftermarket. I used an Eddy on my cutlass and got along great with it.
 
Carbs are alot like socks or underwear. Whatever you like. IF it were me doing a 4bbl on a 273, I myself would do the Edelbrock 500 cfm AVS. Everything else is stock minus the dual exhaust right? Even with a small cam, that should be enuff for the street.

If you plan on pumping it up and start to create some HP under that there hood, Holley has a small street Avenger 570 cfm that would do well. Also a Edel. 600 cfm on a hopped up engine is a good size.
Over 300 HP for the latter carbs mentioned.

The small engine doesn't need to much cfm and would be a bit muddy down low with a carb to big.
 
my father has a factory 273 power pack 4bbl intake and carb he would sell.he ran it on our 78 volare wagon 4spd.for several years.sold the car kept the intake.also have 4 sets of power pak valve covers in excellent condition but don't thing these are for sale.but i know he would sell the intake and carb combo.alson has original chrome? air breather with it..if interested u can contact him at 660-849-2580.his name is Danny.i am certain he would not part with the valve covers.hope this might help in decisions of stock or aftermarket.
 
Did the 1966 have the odd bolt manifolds or was that the 64,65's??? What was the year break on that one again? Flatlander asked me about a manifold I had (cast # 2465726) and I believe this was a 65 only??......Dont want to mislead him. Thanks.
 
64 & 65 have the odd manifold. 66 & later should be the same as a 318, 340, or 360 as far as the size, angle & placement of the bolts.


:burnout:
 
Doing a quick glance at the motor yesterday I found the intake casting #2536559 and the #R 273 225 stamped in the block in front of the LH head. I'm not real clear on the block number. I'll have to pull a valve cover to chech head numbers today.

Dam*ed milkcows don't give me any free evenings.
 
OK, it looks like a 318 according to mymopar. Block casting number 2806030-1 and head casting number 2658920. I'll be starting out with a little more horsepower than what I thought I had, I hope.
 
My '65 Barracuda has the Edelbrock 1406 4bbl 600cfm and I'm quite happy with it. The guy who worked on the car for the last owner said that it now gets about 253 HP. He had tried 2 other 4bbls on it, and a 2bbl, and this one worked the best. I recently put a Pertronix igniter on it , too . I'm not sure if that has increased the horsepower past the 253. It is getting better gas mileage though.
 
If 273 is stamped into the left front face of the block, it isnt a 318. One thing you need to ask yourself; does it need to "look original"? If not, (assuming you have the later bolt angle) you coud certainly do worse than a 1406 Eddy on a Performer manifold, and the factory single plane iron intake would be worse. This would certainly support a bit larger cam down the road, and not kill your low end. Heck, when the old 273 gets tired a 318 short block would still be well served with those same parts. Headers are something to think about I suppose, but for a mild street driven early Dart, I can think of other places to better spend the cash (BRAKES!!!).

Bottom line here, a small 4 barrel and dual exhaust on an otherwise stock 273 or 318 will certainly make an improvement, but don't expect "instant race car". You won't make it worse in any event.
 
Not expecting(or wanting) race car, just more zip and stock is appealing to me. But now I wonder what gives with the casting number 2806030-1?
 
here are pictures of a 1967 dodge dart 273 power pak combo i have for sale for my father.it was on his running volare back in the late 80s early 90s.has been in a trash bag in the shed since.would need cleaned and rebuilt.has the carter afb 4bbl,water neck,fuel line.all include along with factory chrome air breather.would possibly sell a nice set of power pak valve covers if interested.can be contacted at 573-821-6585
jeremy

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