increase HP on a 273

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wstcstjunkie

wstcstjunkie

69 Dart Custom
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Hemet, California
You are probably asking why? do a swap instead! well i would if this car wasn't so clean. i want to keep my 69 dart custom w/273 3spd auto mostly stock. just want to get a few more ponies out of it. can you reccomend a cam, intake, and carb combo that will work?
 
Check the Engine issues forum there is a lot if information on the 273 build there. Here is what I am doing to mine.
Bored 30, deck block and shave heads, balance, 9:1 compression, Custom ground solid lifter cam with specs 20% more that the original 235 hp 4v Commando engine, Eddy performer dual plane intake, Holly 4V carb W/vacume secondaries, Dougs headers and Pertronix ignition conversion. I will build the stock 904 to take a little extra hp and if I can find an a body 8 3/4 so I can get SL I will have what I am after-------Good luck with yours-----
JMHO Rat
 
Intake, carb, cam, wont make much difference without improved exhaust.
If you haven't done anything yet, start with upgrading the charging sytem and the ignition system. The stock stuff from a later model will work better than the original 69.
 
the ignition has been upgraded to electronic, it has dual flowmaster exhaust w/ stock manifolds. not really looking to do a complete rebuild, again just want to add a few more horses. What should i do with the charging system?
 
(Trying this yet again! UGH!)

OK, below is a list f parts that I would consider for upgrading the engine.

Intake; I would look at the Edelbrook Performer or Weiand Action Plus. The small port intakes would be very good for the small engine.

Carb; A 500 cfm Edelbrook/Carter would be right in there though not more than a 600 cfm carb for the 273.

Cam; A cam must work with the rest of the combo. The rest of it is rear gear, tire size and stall of the tranny. I'll assume it is set up from the factory as a people mover equiped with 2.76 or the like gears and the engine is a low compresion engine rather than one of the hi comp HP engines.

For this, I would look at a split duration cam with 6*'s more on the exhaust at a min. since your useing exhaust manifolds. Also, look at the cams RPM range of operation. Since the car was more likely set up as a people mover with low numeric gears, a cam of not more than 216*'s @ .050 should be about the max to look at.

If you have 3.21 gears, 218 @ .050 would be fine.
3.55's and you could move to a 220 @ .050 cam at max.
I say at max because if you exceed this spec, your likely to have a dead spot down low and require yourself a higher stall converter. (More money!)

Comp Cams has a XE256 that would work well.
 
Call Charlie at Camcraft Cams Toll Free (800) 426-2261. Tell him what you have and what you want and he can tell you exactly what you need. He'll grind anything you'd like and is exceptionally reasonable for cam and lifters. I got a cam and lifters for (solids) for $200.00 from him.
 
Good info guys. I believe Camcraft ground the original HP273 cams. The Isky E-4 is close to the factory HP cam. Not a split lift/duration but pretty impressive low end torque. (260/.425/108 deg.) I've been checking out cams on my Dyno program for some time now. A little more cam for the 273 helps a bit but more is not always better. More HP/less Torque at lower (usable) rpm. More lift and duration just makes it run more radical and requires a higher stall convertor and steeper rear gears to make it work. A dual plane intake improves low end torque but watch out for intakes made for 340/360's. The ports are too big and it won't help much. A 600-650 cfm carb is perfect, with vacuum secondaries for an .automatic. The biggest performance increase seems to be headers and free flowing exhaust. The 273 manifolds leave a lot to be desired for free flowing
exhaust. I don't believe you mentioned whether your 273 was a HP or not. The 10.5:1 compression makes a difference. If you have a 2 barrell motor and don't want to over haul it there's not much to do except shave the heads to increase compression. I am planning an overhaul on my hp273 this winter. Other than a bit bigger cam and some head porting it will be a stock rebuild using stock manifolds. The Dyno program figured 322 hp @6000 and 322 tq.@ 4500 rpm. I've tried all sorts of different combinations and this seems to be the best balance. Headers and low restriction exhaust bumped the numbers up over 350 hp and torque. So headers are important for performance. Good luck and keep us posted on your progress. toolmanmike
 
OK OK besides a cam,carb,intake.I would also go with a small stall and 355 gear to make it move a bit quicker.Now please do not beat me with a wet noodle. Jim
 
"No substitute for cubic inches" eh GTS? But like I've said before, we (273 owners) are pretty passionate about our "little engines that could". It's all about rooting for the underdog : at the football game or races.
 
thanks a lot guys, i guess i need to figure out what im working with in the rear before i start bolting things in. is there a way to find out the stall speed in the tranny with out removing it? and what about the rear gear ratio, i can provide a VIN, or tag numbers to help.
 
Ok, so lets say i do the cam,carb,and intake, oh yeah and a decent set of headers. What is my total cost for parts? i am driving the car more and wish it had a little more push. sad to say my honda civic seems to have more power than my dart. there is a 440 on craigslist for $400 but it may need total overhaul, also there is a 383 block, heads and crank for $100. see where i am goin with this.. should stop putting money into my 273 and swap in a bigger motor?
 
What do you want the car to do should be your first thought. After you decide then build it to that goal.
I went down that same road as you with my 273, I now have a 340 in it, if that tells you anything.
 
wstcstjunkie said:
You are probably asking why? do a swap instead! well i would if this car wasn't so clean. i want to keep my 69 dart custom w/273 3spd auto mostly stock. just want to get a few more ponies out of it. can you reccomend a cam, intake, and carb combo that will work?
Click to expand...
this is gonna sound STUPID but look at some chevrolet sites and see the UNBELIEVABLE horsepower there getting from
NA 283's. most of it would be applicable to the 273.
 
Yes there were modded D darts with the 275 hp 273 making 400+ but it takes a lot of money and head work too. You need compressionand that E4 is about a right good choice for a 235-250 hp at the crank build in the under 6200 rpm range.

Need better exhaust too, it is an issue.
 
I was just over at a couple of Chevy sites. Those guys do just what we all do to make horsepower. Lots of compression, lots of camshaft, lots of head work,
and lots of money. There were also a lot of stories about them being built in the late 50's and 60's. Lots of talk about 12.5/1 pistons, 550 lift cams, and dual quads and multiple carbs. Lots of big number estimates of horsepower output without dyno time to back it up.You need to decide how far you want to go to get the results you need for your car. I never wanted to build a 500 hp / 273 for my Dart. That's why I picked the E-4 cam. It will work best for what I need. I spend most of my time between idle and about 4500 rpm. That's where the E-4 works best.
For my basically stock rebuild, I thought 325 hp. is pretty respectable.
toolmanmike
 
Mike...I hear lots people recommending the E-4 cam. Can you tell us how it "feels" (drives) compared to, say, a stock Commando setup? Whats the idle quality like? Low end torque? I'm getting a pair of "302" heads done as we speak for my '67 Dart 'vert, and was considering a cam change at the same time. Is the E-4 a hydraulic or solid cam?

Thanks for the input.
 
wstcstjunkie said:
thanks a lot guys, i guess i need to figure out what im working with in the rear before i start bolting things in. is there a way to find out the stall speed in the tranny with out removing it? and what about the rear gear ratio, i can provide a VIN, or tag numbers to help.
Click to expand...

My book says: Stall 1950-2150 rear gear ratio 2.93 or 3.23. My opinion: Small cubes + adequate engine building = good gas milage and better than normal performance. Ask the leaning engine fellers.
 
65Val said:
Mike...I hear lots people recommending the E-4 cam. Can you tell us how it "feels" (drives) compared to, say, a stock Commando setup? Whats the idle quality like? Low end torque? I'm getting a pair of "302" heads done as we speak for my '67 Dart 'vert, and was considering a cam change at the same time. Is the E-4 a hydraulic or solid cam?

Thanks for the input.
Click to expand...

My drive train is scattered throughout 3 counties about now so I can't show what it will sound like, but Jim (MVR Corp) put one in his Dart/273. It has a great sound. http://www.forabodiesonly.com/mopar/showthread.php?t=72278&highlight=Isky Read through his post for details of his build. I have spent days on the Desktop Dyno program I have experimenting with different cams and specs. I tweaked the stock cam specs and improved the torque and horsepower. I was just about to contact someone for a custom grind and then somone mentioned the E-4. I found more info about it on the Flatlander Racing and the Isky website. When I plugged the specs in the dyno program the torque and horsepower were
an improvement over stock and pretty impressive to about 5000 rpm or so.
By the way, the E-4 is a solid lifter cam. There's lots of solid lifter cams for small blocks out there but most are for racing and don't produce much torque and develop their horsepower at 6000+ rpm. That's not what I wanted.
BabyBlue 66 also has a 273 with a performance cam. http://www.forabodiesonly.com/mopar/showthread.php?t=80039&highlight=toolmanmike His sounds great too!
Check out both of their posts and see what you think. A fresh 273 with a little cam and nice sounding exhaust is what I'm after. toolmanmike
 
Mike...thanks for the links. MVR's sounds real good,although I'd like a little more lope at idle, if I could get it without killing the bottom end torque.

Another question...has anyone tried running the "302" heads with the 273 4 barrel "Pop-Up" pistons? Does this combination work, or is there interference somewhere?

Thanks guys!
 
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