273 power? HOW?

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66 Barracuda

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I thinking of rebuilding a 1966 stock 273 2bbl. What can I do to get some juice out of it? Can the heads be swapped to gain compression? Anything!
 
'64 - '65 and '66 -'67 LA heads have one of the smallest if not the smallest combustion chamber of all the LA heads. Plus your 2bbl 273 should be right at 9:1 and if you want to run regular you don't want to go any higher. I had a 273 in a '69 Fury and just by putting on a Performer intake, 600 Holley and headers with duals the thing ran real well. As a matter of fact the car is long gone but I still have the motor I was so impressed with it. Next stop for that little 273 is in my '85 Cherokee XJ. If you motor needs a complete rebuild it will probably cost you more doing the 273 that doing a 318 or 360 because the pistons are harder to get and are more expensive.


Chuck
 
I really don't know how much power I'm producing or anything like that but I am impressed by my little 273 also.
 
To maintain reasonble cost effect street driveability use 1 HP per Cubic inch.

You can go more but you'll run into alot of compromises along the way with drive line traction and just plain tearing sh*t up.

273 = 275 HP
360 = 360HP
440 = 440 HP

Just sensible and cost efficient number to guide you in your project.
 
The 66 D dart was rated at 275 hp and they did it with a stock 4 bbl manifold.
It had a hotter cam, better springs, headers and a holley 4bbl. Anything you can do to help it breath better helps. The stock compression ratio is great for a street car.
 
I've got an aluminum 4bbl Edelbrock SP2-P intake that I just pulled and had tanked at a machine shop. It's got intake ports that are great for a 273 or 318 velocity-wise, and it's got mounting provisions for spread-bore carburetors or square bore carburetors with a small, commercially available adapter. It uses the same bolt pattern as the 318, 340, and 360 to mount to the heads.

I'm currently asking $140 obo. If you're interested, drop me an e-mail.
 
The heads have smaller attaching bolts @ 5-16th. This makes a machining of the block to open the holes up for other heads a mandorty thing to do. HOWEVER;

You'll just need to pocket port the heads and backcutting the valves would be a good addition to low end flow. A light milling only to true yp the surface IF and only IF it needs it. The above idea of not to much compresion is very dead on and true. No sense looking for trouble.

Easy on the cam, a mild one will do wonders in the lil'engine that can.

The hardest part here is finding a intake to fit the heads. Look for old Edelbrock intake manifolds or go to offenhauser to get one.

Standard headers will fit and work well.

TWX, will that fit the earlier LA engines?
 
If your rebuilding your 273, you might need an overbore and that means new pistons. I thought of this about 6 years ago, but didn't want to spend 600 dollars for custom pistons. 273's can run well, but 360's run better for less money.
 
Was 315 HP at the crank and displayed 245 to the rear at 6200rpm on a clayton dyno.

I have a holley street dominator for the 273 for sale, works good, you can open up the ports some, do a good 4-5 angle valve job, back cut the valves, go with a solid cam and stiff valve springs. If you do new guides you could get a 1.55-1.60 exh. and maybe a little bigger Intake, but the cylinders need to be nothed if you get to big then you get shrouding etc and ruin flow a bit too.

You need a .480 to .500 lift cam with short durationand a fast flank to match the early D darts that made 275 HP. Good ignition, and a 625 AFB is enough too.

They are a little sanppy but once in the 3500 and up range pull very decent. Just dont over cam for a street car. And I would not get to crazy on other heads as mentioned either. Actually the early heads have a quench are that allows more compression which if you go with more ill be required, so stay about 10:1 or less but not under 9:1 or low end really suffers.

Also I found about 2800-3200 stall is good with a 3.55 for a street car, more like 3.91 if you do little freeway use.

I have several 273 parts up for sale so maybe I could save you a few $$s.

enjoy!
 
I,d start out by reading the mopar speed secrets book as it has recipes for motors from mild to wild.
 
And then I would switch to a split duration cam with as much lift as I could squeeeeeeeeeeze in and keep the stock intake valve, swap to 1 .60 exhaust valve. No need to notch the cylinder wall for a 1.88 valve.
 
the 66 to 69 273 used same size intake bolts as 318/340/360/, 3/8 and same angle. the 64-65 273 had 5/16 intake bolts and different angle. a 360 intake and exhaust sst valves can be cut down to 1.84 and 1.56, this will help airflow and doesn't shroud the chamber walls. the port velocity remains high.
the 2 bbl motor piston has a deck hgt of -.011 with a .028 gasket and 273 head at 57.3 cc, comp ratio can be 9.77. there is a few 2 bbl 273 in stock eliminator, T/S 65 plymouth runs 13.30,s a 235/273 valient in I/SA runs 12,30.s, its a great little motor,
 
why waste your money and time? it'll cost about the same to hop up a 360 and easier as well. you would also gain over 90 cubes at the same weight.
 
You get a lot more bang for the buck from a 360. Drops right in.
I'm building a 273 commando engine for it's appearance. The only thing I want other than its' stock equipment is the magnum exhaust manifolds and a little larger exhaust pipe with 1 flowmaster.
 
I was amazed by just the changing of my stock 2 bbl intake for the Commando/Charger 4 bbl cast intake and '67 Carter 273 AFB...it's like night and day,the difference. I still have my stock '67 exhaust manifolds AND single exhaust. It goes good enough for me.
 
bobscuda67 said:
If your rebuilding your 273, you might need an overbore and that means new pistons. I thought of this about 6 years ago, but didn't want to spend 600 dollars for custom pistons. 273's can run well, but 360's run better for less money.
Click to expand...

As others have said - if you have to rebuild and are OK with things being non-stock, really think about all your options long and hard before choosing an option. There is a lot to consider and the more HP you have, the more other things need to be considered (transmission/rear-end)

Also, one thing to think about is the resale after all is said and done. Even if it's overpowered and you can't get traction, a 340/360 is always going to help things sell compared to a 2brrl 273.

Of this is just my opinion.
 
jahsh said:
Also, one thing to think about is the resale after all is said and done. Even if it's overpowered and you can't get traction, a 340/360 is always going to help things sell compared to a 2brrl 273.

Of this is just my opinion.
Click to expand...

I wanted to big block my car when I first bought it. But then after realizing how much is involved in having a streetable big block A-body I backed out. Torsion bars,disk brakes,motor mounts, is top of list of the things I would have to gather.
I would hate to remove the 273 because the VIN number shows that the car came with the 273. Now I'm not totally sure its the correct motor that came with the car however but it might be the original. I have thought about a nice built 360 would cheer things up a bit but I would not get rid of the 273 altogether. I believe the 273 are slowly getting hard to find but I could be wrong.
 
I thinknow days more people are looking for 273s for A-body restore projects which is making them harder to find.
Somewhere I read about a guy trying alternative pistons. Pontiac maybe ?(dunt remember)
Near the same diminsions though and affordable at about 32 bucks each.
 
I think that there's no reason to re-build a 273 other than to keep a particular car stock. I know they run very well but if you go to the trouble to rebuild something get the most you can get.

A larger engine means more torque at lower speeds and this is what you'll really feel. You'll notice a huge difference if you get a mild 360 to replace a 273 especially if it's a 2 barrel.
 
go too the 1962-1965 mopar website and read info on tech forms

Also allpar.com has the info you seek!:computer::hello2::bounce::hello1::happy1 ::D :burnout: Good luck
 
RedFish said:
I thinknow days more people are looking for 273s for A-body restore projects which is making them harder to find.
Somewhere I read about a guy trying alternative pistons. Pontiac maybe ?(dunt remember)
Near the same diminsions though and affordable at about 32 bucks each.
Click to expand...

The pistons for my 273 cost $294.48!
 
RedFish said:
I thinknow days more people are looking for 273s for A-body restore projects which is making them harder to find.
Somewhere I read about a guy trying alternative pistons. Pontiac maybe ?(dunt remember)
Near the same diminsions though and affordable at about 32 bucks each.
Click to expand...

I have two I'd love to get rid of for cheap, just so they can be used. I myself haven't seen that they are in all that much demand.

Yes, I think people love to restore the Formulas 'S' cars and keep things looking stock - but I can't think of one example of a restored 2brrl car - yeah I'm sure there is a few cases, but not many.
 
It depends on what your goal is. If you want a motor that looks the same as the 273 - then a 318, 340, 360 can be made to look the same by using the external parts, like the chain cover, water pump, alt brackets, pulleys etc from the 273. What I did was drop a 318 in mine with all the 273 stuff hanging on it.

I have not looked into buying new pistons for one of these motors recently, but I bought two sets off of ebay a few years ago that were brandy new, a 060 and a .030 set for a 273. The .060 cost $20 for eight !! The .030 set cost 100$ with new rings. These werent anything special, just regular dumb old cast (new) 9:1 pistons. The deals are out there if you are willling to look.

What I'd suggest doing, if you want to keep the 273, is rebuild it using a 9:1 set of pistons, rebuild the heads with hard valve seats on the xhst, a mild bowl and runner port job, and a stock 340 cam with a dual plane intake, or the oe 273 4bbl intake, and no more than a 600 cfm carb with headers. Should be good for 275-300 hp.

Have fun deciding - remember it will cost about the same to do any of these motors -
 
I have been giving that some thought also.To change engines and make it look stock.I have my hands on a 340 or a 360 and thinking of putting all my 273 stuff on it or turn my 273 2bbl. to a 4 bbl. car.Either way I would have to rebuild each motor.I guess one of my questions would be is would the motor mounts,balancer,and timing cover from my 273 fit the 340 motor?
 
Don't mix the balancers around. Use the original one intended for the 273 or the 340 whichever you decide to use. The 340 balancers are thicker but have the same pulley spacing.
 
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