My 273 Experiment

[Hyper_pak]

Thanks to cross_thread72 I now have a 273 Block.
I have wanted to build a small block for a few years now, so I am going to slowly build a 273 with a few parts I have located along the way.
Feel free to chime in with your ideas!
The engine will run in the Colt after I get that going so it's a few years away.
Baseline:
I want it to look like a 273 Commando, so Factory Covers and Air Cleaner
273 block, bore ?
318-3 crank
318 Swirl port heads
Crane Fireball Cam, Specs ?, 273 adjustable rockers
LD4B Intake
Electronic Ignition
650 4777 Double Pump Carb
Tube Headers
Manual Transmission
Lots of gear and Tire.

 

[chryslerfat]

Why not keep the 273 steel crank?

 

[clifftt]

X2

 

[toolmanmike]

x3 Looks like you have a great start. Are you going to have flat top pistons made for a zero deck motor? tmm

 

[PocketAces]

I'm in the middle of building a 273 for my Dart. I've learned that there are not a lot of options for pistons and they are expensive. You end up with a smaller motor that costs more, weighs more and makes less power. Since it's going into a Colt, originality is not a concern so you might as well build a 318. All the 273 dress up parts will bolt onto a 318 and nobody will be able to tell the difference unless they look at the numbers on the side of the block. Sorry to be a downer.

 

[bamacuda]

Sweet!

 

[RedFish]

You'll need to alter the base plate of that air cleaner for any other than the stock carb'.
318 minus 273 equals how many reasons we can post on why not to build a 273 for anything other than a correct restoration it belongs to.
Yeah I've gathered every piece to build my 67 vert as a 273 Commando clone but only for the show.

 

[Hipo65]

They are a little more $$$ but built right it will suprise you! thease motors like short duraiton tall lift cams & higher compression really helps too. id build the 273 man. X4 on running the 273 steel crank. Mine is really close to stock specs other than pertronix & E-4 cam with 1.6raito rockers & it kept right bside a sweet looken 70 road runner with a close to stoch 383 hp until 115mph then wy wife yelled @ me to lift. nevr lost an inch. that guy was impressed "ive got 110 cubic inches on you & you didnt lose an inch" that aint rite.

 

[Hyper_pak]

Great Comments! Keep them coming!
Here is a little more info, All I got was the bare block, nothing else.
I have a 318-3 truck crank, I don't have a 273 crank.
I run slant sixes, so I am not too smart, 273 just sounds like the underdog route.
I have 2 sets of 273 2 barrel pistons and rod sets, no 4 barrel stuff.
I can run a small adaptor on the intake for the carb.

 

[Robbie2734]

Great little motor, I'd go for it! You'll be surprised in a light A body, they really do make power. I like your combination.

 

[Abodybomber]

Manual Transmission
Lots of gear and Tire.
THIS...^^^…
As for Crane "Fireball " cam specs: look for a number stamped ,on the end of the camshaft. "288/296" are the most common ones. Slow adverised ,with roughly 215-230 @ .050 lift.Lift ranges from .450-.500" on these grinds.Usually a hydraulic cam,a solid could pop up(rare!). I would work on pocket porting /GOOD valve job & getting compression up. Like this combo.

 

[jerry6]

I don't know much about the 273 , so excuse if it's stupid , can you use pistons from another small block ? I like the idea of a 273 screamer , my mom had a 68 Dart convertible with the 273 4 bbl , I used to get her pissed off while driving cause when she would stomp on the gas and it smoked the tires , great little motor .
Go for the 273 , everyone has a 340 or 360

 

[toolmanmike]

I don't know much about the 273 , so excuse if it's stupid , can you use pistons from another small block ? I like the idea of a 273 screamer , my mom had a 68 Dart convertible with the 273 4 bbl , I used to get her pissed off while driving cause when she would stomp on the gas and it smoked the tires , great little motor .
Go for the 273 , everyone has a 340 or 360

I agree. Build it. The pistons and rings will cost more but the other parts are the same as any other small block. tmm

 

[chewy]

I'm also in agreement, id go for the 273 build, these little 273's are fast revving, and surprise many, as to how high you can take the rpms before float occurs, and how quick they can pick up and move when dialed In right.

I love some of the stories my dad tells me about my dart when he used to drive it daily out to thiokol. One of my favorites is the 442 that was messing (one of his co workers) with him on the old highway out to work for about 10 miles, and he got tired of it, dropped it from fourth to second and romped on it, breaking tires loose in second, third and then fourth gear. Leaving the GM bunch in the dust. They didn't catch up for a number of miles. Driver was totally embarrassed and his carpoolers never let him live it down. The guy ended up selling the car shortly after, trading down to a 326 firebird that just looked pretty.

At any rate, my point is, yes u can build more horses in a 340/360 setup, but, the little LA can be as fun. If u have the parts and want, I'd say go for it.

 

[2 Darts]

Bore on a 273 is 3.625. Egge Speed Shop stocks up to .060 over for the 10.25:1 style piston.

I believe that the Crane Fireball is a hydraulic cam.

Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,800-5,500
Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 228
Duration at 050 inch Lift: 218 int./228 exh.
Advertised Intake Duration: 276
Advertised Exhaust Duration: 288
Advertised Duration: 276 int./288 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.441 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.441 in.
Valve Lift with Factory Rocker Arm Ratio: 0.441 int./0.441 exh.
Lobe Separation (degrees): 114
Computer-Controlled Compatible: No
Valve Springs Required: Yes
Camshaft Manufacturers Description: Fair-smooth idle, low-midrange power. Works with stock-2,000 stall, 9:1 and higher compression, and gearing.

I have this cam in a 318, 302 heads (9.2:1 CR), 625 cfm AFB, 904, in my 72 Demon and have enjoyed it.

 

[omahamoparguy]

... a 318-3 truck crank is way,way way overkill in a 273. did you know those cranks are good for 8000 rpm (what I have heard). they are heavy and I am not sure but I think they have a different flange on the end. But if you've got one....I guess you could use it. Just a cast 318 crank would be just fine or a steel crank from a 67 318. Even a 318 poly crank would work (they are steel, most of them) the cast crank would be lighter...

 

[67Dart273]

I'm in the middle of building a 273 for my Dart. I've learned that there are not a lot of options for pistons and they are expensive. You end up with a smaller motor that costs more, weighs more and makes less power. Since it's going into a Colt, originality is not a concern so you might as well build a 318. All the 273 dress up parts will bolt onto a 318 and nobody will be able to tell the difference unless they look at the numbers on the side of the block. Sorry to be a downer.

 

[66fs]

273 all the way. Should be able to get 9.0 CR from 2 barrel pistons. If the clearance is good and the lands are good, run what you have. The carb should fit directly to your LD4B. Base of the Air cleaner is small for a Holley, I'm sure someone will trade you, or get a 10 in Edelbrock air cleaner and use that base. I'd sell the Crane and get a smaller solid cam, but what you have will work. Check for clearance between rocker arms and valve springs. Check your crank for pilot bushing, since we are talking 4 speed and while it is apart. Sounds like you are good to go.

 

[Hyper_pak]

All good stuff! Thanks guys, I hope to get bore measured this weekend and check my pistons. C 273 means a low compression 273 correct?

 

[67 Power Wagon]

Everyone builds big block Mopar (HELL, I've got one to build!) and never hear of many doing small block LA Mopar engines, so I say, GO FER IT! Small Block Mopar is better then ANYTHING Brand X.....And the 273 most steer from due to their small size, but they still can rev pretty good! As said there are 8000 RPM cranks made, which go a long ways on a short stroke engine!

 

[toddlum]

273 all the way... Have a 273 4speed 66 barracuda that hauls some serious butt.great little engine that likes the R's.With 8 3/4 sure grip with 3:55's kit can get alittle hairy.