67_Slimer
Real Hot Rods don't shift themselves.
So no matter what I get out of this post , at least I know I'm "pathetic"
273 or NOT 273?
- Thread starter 67_Slimer
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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If you want cheap, go 360.
----------------------------------
I'm not a 273/318 hater. But
I'm going straight for "swept area"; and I'm willing to detune my bigger-inch engine to match the power of a hopped-up 273, and then be able to drive nearly twice as far on the same amount of fuel.......... with a cam nearly 2 sizes smaller, all-the while enjoying the fatter midrange.
Now,
if instead of a 67A-body, you had said 66 or older, which are lightweight-As, something like 300 pounds lighter; I'd not preach the big-bore advantage, which in those, all just goes to tirespin anyway.
------------------------------------
Back in about 74, at age 21, I built one of those with a 340, even with a 318 top end and a 318 cam, she was a tire-frying torque-monster! lots and lots of tirespin. That car I built from laying-around-junk and left-over parts from other guys cast-offs. It turned out to be my Third favorite of all-time combos; maybe even Second favorite.
-----------------------------------------------------------
As for 360s;
Mine went together with 40 over KB107s (502grams) that landed at .012 below deck... With factory bushed 318 rods, and the lightweight pistons, mine was easy to balance externally. With 028 gaskets, and .012 decks, the Q was 040, and with small-chamber, big-port alloy heads, she was good for 11.1 Scr.
I later reset the deck-height to .007pop-up, and switched to an 039 gasket, the Q going to .032. With a few cheap oiling mods, and decent valvesprings, the valve gear goes 7200 all day long. As a streeter, this set-up was ready for any decent street cam.
Speaking of cams;
My first cam was the Mopar 292/292/108.. She drove 5.6mph@650 rpm, with a starter-gear of 9.44, but it was a struggle. Even with a starter gear of 10.97, I just could not drive slow enough to parade it. Well I could but, at typical Idle-Timing, she just wanted to buck down there, which then needed a toe on the clutch all the time.
My second cam was a 223/230/110, This cam had the potential for over 30 mpg, geared 65= 1600rpm; and with a starter of 10.97, this drove 3.6mph@500rpm. This made just enough Power to get into the 12s on 245 street tires. This was my favorite cam.
My third cam, 230/237/110* drives 4mph@550rpm. This has gone 93 in the 1/8th, at 3457 pounds, at 900ft elevation, on 295 street tires. The Wallace Calculator makes this out to be 433hp. But this 230*cam is NOT easy on gas.
In it's final iteration,
it's now running with a Commando 4-speed, 3.55s, and a GVod, which is often being used as a splitter. I have tried seven gears; but on the street, that was just too much; Five gears is all I need. In the 1/8th, 4 gears is all I need. She is currently geared 65=2240..
With what I learned over the last twenty years with that engine, I now have a pretty good idea of what my next cam should be ......... but I doubt there will be a next cam, as the current 230 cam, just won't die! This engine now has well over 100,000 miles on it.
BTW,
with those alloy heads, right from the beginning in 1999, she has always run on 87E10 gas, even at up to 195psi.
BTW2
Well, but.... I'm 25 years older now, and I must admit that I could be happy with a hi-compression 273/318; BUT, with a tiny solid-lifter street cam, and that A833-Commando/GVod, is looking pretty good. I'd be looking for a gear to be revved out in, at ~60 mph. The math points to ~7.76Roadgear, Which could be 1.92Second and 4.10s, which hits 60@ 5880, sounds good.. Using the Splitter, that would be 3 gears/2 shifts. But cruising at 65=2600 in od.
But, I'm also thinking, that these days, I could be just as happy with a hi-stalled A500LU, and something like 4.30s; for 60=~5500 in Second, and 65=2400 locked up in od. But as you can see, this combo really has no useful passing gear on the hiway, so I'd be looking at, at least a 318, to use less rear gear.
But a Magnum top end on a 340 with a small cam, and less gear, would restore the passing gear; yeah I'm liking that thought. Jus not with the heavy forged pistons, nor with that factory 340 cam..
But if yur willing to go that far, you might as well just start with a Magnum, but throw away the factory cam. and, if it was me, I'd install some really small chamber alloy heads and crank up the pressure!
To me in my streeter, pressure and the right gear, is worth way more than over-the-nose absolute power....... Cuz think about it; most streeters, in most situations, are not going much over the speed limit, which with street gears, means yur onlybuzzing her up to shift-rpm, just once, cuz 5500 with 3.55s is gonna get you 80 mph, in Second (Auto).
So then, yur gonna need a lotta midrange torque, to give you that kick-in-the-azz feeling .... which points straight to cubes, or lots of Cylinder pressure. Cubes is usually cheaper than pressure, especially as you cross the detonation line near 165psi on pumpgas, with iron heads. So if yur stuck with iron, you might as well go 340/360 . But if you can afford alloy heads and your design can accommodate enough Scr, then a 318 can be used. But to get decent pressure out of an alloy-headed 273, is gonna take a lot of Scr, which with off-the-shelf pistons, is gonna be hard. and if I'm gonna fork over the dough for alloy heads, I'm sure gonna need a special reason to put them on a 273. .... cuz on a 318, I'm already looking at plus 45 cubes and an easy 40 hp, just on those cubes! never mind the torque boost from stall to ~3600, the range in which most of your city driving is gonna be. Forty hp, at this level, is like two cam sizes! That's a lotta fuel-economy sacrifice just to say you have a legendary 273.
----------------------------------
I'm not a 273/318 hater. But
I'm going straight for "swept area"; and I'm willing to detune my bigger-inch engine to match the power of a hopped-up 273, and then be able to drive nearly twice as far on the same amount of fuel.......... with a cam nearly 2 sizes smaller, all-the while enjoying the fatter midrange.
Now,
if instead of a 67A-body, you had said 66 or older, which are lightweight-As, something like 300 pounds lighter; I'd not preach the big-bore advantage, which in those, all just goes to tirespin anyway.
------------------------------------
Back in about 74, at age 21, I built one of those with a 340, even with a 318 top end and a 318 cam, she was a tire-frying torque-monster! lots and lots of tirespin. That car I built from laying-around-junk and left-over parts from other guys cast-offs. It turned out to be my Third favorite of all-time combos; maybe even Second favorite.
-----------------------------------------------------------
As for 360s;
Mine went together with 40 over KB107s (502grams) that landed at .012 below deck... With factory bushed 318 rods, and the lightweight pistons, mine was easy to balance externally. With 028 gaskets, and .012 decks, the Q was 040, and with small-chamber, big-port alloy heads, she was good for 11.1 Scr.
I later reset the deck-height to .007pop-up, and switched to an 039 gasket, the Q going to .032. With a few cheap oiling mods, and decent valvesprings, the valve gear goes 7200 all day long. As a streeter, this set-up was ready for any decent street cam.
Speaking of cams;
My first cam was the Mopar 292/292/108.. She drove 5.6mph@650 rpm, with a starter-gear of 9.44, but it was a struggle. Even with a starter gear of 10.97, I just could not drive slow enough to parade it. Well I could but, at typical Idle-Timing, she just wanted to buck down there, which then needed a toe on the clutch all the time.
My second cam was a 223/230/110, This cam had the potential for over 30 mpg, geared 65= 1600rpm; and with a starter of 10.97, this drove 3.6mph@500rpm. This made just enough Power to get into the 12s on 245 street tires. This was my favorite cam.
My third cam, 230/237/110* drives 4mph@550rpm. This has gone 93 in the 1/8th, at 3457 pounds, at 900ft elevation, on 295 street tires. The Wallace Calculator makes this out to be 433hp. But this 230*cam is NOT easy on gas.
In it's final iteration,
it's now running with a Commando 4-speed, 3.55s, and a GVod, which is often being used as a splitter. I have tried seven gears; but on the street, that was just too much; Five gears is all I need. In the 1/8th, 4 gears is all I need. She is currently geared 65=2240..
With what I learned over the last twenty years with that engine, I now have a pretty good idea of what my next cam should be ......... but I doubt there will be a next cam, as the current 230 cam, just won't die! This engine now has well over 100,000 miles on it.
BTW,
with those alloy heads, right from the beginning in 1999, she has always run on 87E10 gas, even at up to 195psi.
BTW2
Well, but.... I'm 25 years older now, and I must admit that I could be happy with a hi-compression 273/318; BUT, with a tiny solid-lifter street cam, and that A833-Commando/GVod, is looking pretty good. I'd be looking for a gear to be revved out in, at ~60 mph. The math points to ~7.76Roadgear, Which could be 1.92Second and 4.10s, which hits 60@ 5880, sounds good.. Using the Splitter, that would be 3 gears/2 shifts. But cruising at 65=2600 in od.
But, I'm also thinking, that these days, I could be just as happy with a hi-stalled A500LU, and something like 4.30s; for 60=~5500 in Second, and 65=2400 locked up in od. But as you can see, this combo really has no useful passing gear on the hiway, so I'd be looking at, at least a 318, to use less rear gear.
But a Magnum top end on a 340 with a small cam, and less gear, would restore the passing gear; yeah I'm liking that thought. Jus not with the heavy forged pistons, nor with that factory 340 cam..
But if yur willing to go that far, you might as well just start with a Magnum, but throw away the factory cam. and, if it was me, I'd install some really small chamber alloy heads and crank up the pressure!
To me in my streeter, pressure and the right gear, is worth way more than over-the-nose absolute power....... Cuz think about it; most streeters, in most situations, are not going much over the speed limit, which with street gears, means yur onlybuzzing her up to shift-rpm, just once, cuz 5500 with 3.55s is gonna get you 80 mph, in Second (Auto).
So then, yur gonna need a lotta midrange torque, to give you that kick-in-the-azz feeling .... which points straight to cubes, or lots of Cylinder pressure. Cubes is usually cheaper than pressure, especially as you cross the detonation line near 165psi on pumpgas, with iron heads. So if yur stuck with iron, you might as well go 340/360 . But if you can afford alloy heads and your design can accommodate enough Scr, then a 318 can be used. But to get decent pressure out of an alloy-headed 273, is gonna take a lot of Scr, which with off-the-shelf pistons, is gonna be hard. and if I'm gonna fork over the dough for alloy heads, I'm sure gonna need a special reason to put them on a 273. .... cuz on a 318, I'm already looking at plus 45 cubes and an easy 40 hp, just on those cubes! never mind the torque boost from stall to ~3600, the range in which most of your city driving is gonna be. Forty hp, at this level, is like two cam sizes! That's a lotta fuel-economy sacrifice just to say you have a legendary 273.
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NC Engine Builder
Grumpy Old Man
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I wasn't addressing you personally. But spending large amounts of money, and running 12s is not impressive these days. Now if you do it with a backyard re-ring build, then it could be considered impressive. I have no idea what you built or what you spent.
NC Engine Builder
Grumpy Old Man
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But the bottom line is, a 273 that runs 12s in a 3200lb street car is going to be a tough build. More expensive than a 318-340-360, and less torque than any of them. It will basically be a temperamental race engine that you try to make street friendly, and will likely be a exercise in dissatisfaction. Put a 4" crank in your current 340, refresh the engine as needed, and be miles ahead and have money left in your pocket when your done.
dibbons
Well-Known Member
I ran best of 12.72 (108 mph) in a 2960 lb. Valiant (street legal at the time) with stock cylinder heads/valves. To go half a second faster would have broke the bank I'm sure.
67_Slimer
Real Hot Rods don't shift themselves.
I don't want a 4" crank , If I stay 340 I will use the stock stroke. I like to rev and my car is a 4 speed so cam choice isn't really a problem and I have 4.56s so a tourque stroker that is done at 6k isn't in my list of goodies. Every car I see now has a stroker , I'm old school. I like to rev , Make a buzz saw that rips. Might not be fast but I guarantee that it will be impressive for what it is. I have a stock bore 340 block that I might work with but I'm really thinking about a 273. Confused at the moment.
67_Slimer
Real Hot Rods don't shift themselves.
Thats awesome!! 273? what intake? gear? tranny? compression? cam?
NC Engine Builder
Grumpy Old Man
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Gotcha, well the stock stroke 340 would be my suggestion for what you want, with your particular stipulations. The 273 is doable, just more expensive, and probably shorter lifespan
Newbomb Turk
Well-Known Member
Don’t think I haven’t thought of a 3.79 crank in a 273.
I can never get my mind to accept a bore that small.
Small bores kill power for several reasons. I hate killing power for no reason.
Makes sense, but to me the question is the bore big enough to reach the OP's goal? low 12's, I don't see no reason that can't with basic hot rodding.
67_Slimer
Real Hot Rods don't shift themselves.
NC Engine Builder
Grumpy Old Man
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Depends on how it sonic checks
67_Slimer
Real Hot Rods don't shift themselves.
So lets say a .030 over 273 , ported set of 318 heads , port match a victor intake , solid flat tappet cam , 1.6 roller rockers , 12/1 pistons , lighter rods , stock steel crank , 750 HP carb , 1 5/8 headers , 4 speed and 4.56s. does that sound like it would work on a 273? Not exactly but just a rough draft.
Newbomb Turk
Well-Known Member
It’s like NC said above. Low 12’s in a 3300 pound car takes about 375 honest horsepower to run low 12’s. You might not get the ET but the MPH should show enough to get a low 12 pass.
You already know this but with the bore limits it makes it that much harder for the same cylinder head to make power.
A 340 at 375 hp is 1.1029 hp/cid.
A 273 at 375 hp is 1.3736 hp/cid.
Two tenths of a point don’t sound like much but when you are bore limited it’s a bear to get it.
Doing the same math a 408 is .9191 hp/cid.
Even with a 4.56 gear and a 27 inch tall tire about 6500 rpm. For some guys that’s a deal breaker.
Here's a handy chart. Another piston option for the 273.
Newbomb Turk
Well-Known Member
Use a 360 head and 1.88 valves and notch the block.
A 318 head is too small for a 273. By a ways.
NC Engine Builder
Grumpy Old Man
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Not a bad recipe, but I'd either do a magnum head, or a 340/360 casting. The 318 casting lacks enough port cross section imo. And nothing is truly exotic about it, but if I were doing it, I would have a custom piston made for it, chevy pin diameter, and a metric ring package. The ring package alone is reason enough to go custom. With that, you can turn your 273 crankshaft rod journal to the generic "chevy" size, and have a much better selection of shelf rods, in numerous lengths. Allows you to shorten up the excessively tall compression height of the factory type pistons
It would work. 300+ horse depending on the cam. Just guessing. The 273's small bore is where it chokes. A lot of power comes from the heads with big valves and free flow. You can only fit a bit larger than stock valves in the small bore with out notching the block. It can be done. Go ahead and try and record the procedure. Make sure you either dyno it or take it to the strip so we can see the power levels. I have followed a few members here that have built 273's but they either didn't finish them or never got any horsepower readings. No real good reason to bust your pocketbook to get 350 horse when you can do that fairly easy with a 318 or even easier with a 340.
Dartswinger70
Well-Known Member
12s I dunno but I d bet its boring I mean like running a street car down the track boring. I have stock street cars that Ibve had at test and tune. a guy I know recently said "I thought youd be running your car" I said "well its a street cruiser and I hadnt really modded it , I know how fast it goes..." I think point is I can run the thing down the street for free I dont need timeslips for a 12 or slower car(My car in question here doesn't do 12s no Its not Mopar LOL!)
Some say you can go to a 305 bore 3.75" (292), but definitely a sonic check would tell you.
Egge
dibbons
Well-Known Member
Starting from the top: Velocity stack, 600 cfm Holley double pumper carb, stock cylinder heads re-surfaced (gasket matched with Dremel tool) with blocked crossover passage and steel shim head gaskets using copper wire placed in gasket bore ring as a kind of "poor man's" o-ringed block, polished stock valves, cylinder block bored .060 over and decks resurfaced and oil drain back holes drilled in lifter valley, inside surfaces of block de-burred and painted inside with Rust-Oleum rusty metal red primer, splash shield in lifter valley to prevent hot oil from heating bottom of intake manifold, factory 273 adjustable rocker arms, chromed stock rocker arm shafts, Isky 1012B solid lifter camshaft and lifters (.580 lift and 312 advertised duration), Isky dual valve springs with dampers, chrome moly pushrods, aluminum valve retainers, knurled valve guides, teflon valve seals, TRW forged dome pistons (10.5:1), connecting rods reconditioned with aftermarket bolts (factory full-floating pins), beams polished smooth and then shot-peened, 318 forged truck crankshaft, rotating assembly balanced, main and rod bearing clearances of .003" with full oil grooves on Clevite main bearings, stock oil pan and pick-up deepened by 2 inches, high volume oil pump, double-roller timing chain, Chrysler electronic ignition (blue box), Packard 440 spark plug wires with Rajah snap terminals, Champion N9Y spark plugs, orange performance flex fan (these days not recommended), 160 degree thermostat with stock radiator, Cyclone fenderwell headers (not equal length), round aluminum cool can and dual see-thru fuel filters at carb pumped to the front with Holley electric fuel pump and pressure regulator, 1/2" aluminum fuel line, trunk mounted battery with welding cable as positive cable.
Drive train: Full syncro Chrysler A833 four-speed built by Pepe's rear ends in Los Angeles (3.09 low gear later replaced by 2.66 low gear version), 1970 Challenger 8 3/4 sure-grip differential (4.56 ratio), super-stock leaf springs and super stock rear shocks w/pinion snubber, 10 inch wide M & H slicks on black rims with rim screws (inflated to 10 psi), custom balanced drive shaft retaining ball & trunnion front joint and Zoom rear u-joint (without grease fitting for strength), drive shaft safety loop, bolt-on frame connectors, VW 15 inch front tires on narrow Centerline wheels, Lakewood scatter shield, and Mcleod diaphragm clutch, 30 lb. steel flywheel, firewall brace to eliminate clutch movement. Manual steering and manual drum brakes with metallic linings. Stewart Warner mechanical oil pressure gauge mounted on cowl outside windshield in plain view, 8,000 RPM Sun tach mounted on top of dash, Hurst shifter linkage with pistol-grip shifter later replaced by T-handle canted 45 degrees to the right to assist in power shifting. Full seats, windows, horn, rear bumper, headliner but heater box, front bumper, and floor coverings removed. In street trim: dual turbo mufflers with 2 1/2 inch pipes dumping in front of rear axle.
Bracket Racing Routine: One brief water burnout in second gear, then launch from starting line with engine turning 6,000 rpm and the same 6,000 rpm shift points (always full-power shifts with accelerator never lifted from the the floor until passing the finish line). Trap speed was 6,400 rpm and still climbing rather fast (probably could have used a 4.89 or lower rear end ratio). Used an rpm limiter (don't remember where it was set-must have been 6,500 rpm or higher). Oh, I built the vehicle at my Auto Technology class while attending Hartnell Community College in Salinas, California circa 1973-74. I believe I performed all the work except for polishing the crankshaft for clearance and balancing the rotating assembly.
Renteria Brothers purchased my Valiant in 1980 and installed a 340 (first photo) and then they went to a big block and painted it black (second and third photos):
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This is I think P.I.E build
The 273 Build That Doesn't Suck
Forget The Little Engine That Could. This Is The Little Engine That Does!
WARNING: Reading this article might cause you to giggle uncontrollably with excitement. It might lead to sleepless nights and neglected work-hours spent planning your own 273 build. It might have you scrounging vintage salvage yards, the classifieds and maybe even strangers' back yards looking for neglected 273 cores. It might even lead you to abandon all rational engine building protocol in the quest to create your own dare-to-be-different scream machine.
We are not responsible for any of this. However, if you choose to build an engine like this, we'll be right there to help you build it.
A few months ago, Chris Sockriter stops into our shop with that glint in his eye and a plan in his head to build a hot 273 for his 69 Dodge Dart. Now if this was 1965 and the 273 was still a serious D/Stock contender, we might have been just as excited as Chris to build this engine, but the fact is, MOPAR's tiniest small block is just that- tiny- and as anyone who builds or has had an engine built for them knows, bigger engines make more power for less money. In other words, why build a 273 for power when you can build a 360 that will make more power for less money? While you're at it, why not build a 408? In comparison, they're even cheaper than 360's when it comes to producing power for pesos.
But like we said, Chris had that glint in his eye, a plan in his head and money in his pocket and all of them were targeted to build the 273. So we kept listening. And that's when things started to get interesting. Turns out Chris didn't just want us to build a hot 273, he wanted us to build one with a hair dryer- aka- a turbo (or two), for some stick-shifted silliness in that Dart we mentioned earlier. Now we started getting that glint in our eye too. This could be fun. Sure, the 273 is still small but throw some turbos at it and it gets quite a bit bigger. Factor in the advantage that Chris already had the engine and that its factory forged crank is plenty tough for boosting and beating and the higher costs generally associated with building small engines might not be so high. So we devised a plan to build a simple, stout, small block that's just a huff-job away from becoming a hero.
Building For Boost
With the plan established that this was going to be a turbo engine, we got to work on prepping and building for boost which in this case, like every case, meant first building a solid and excellent performing naturally aspirated engine. To do this, we spec'd out a package that included a mix of tried and true components along with some creatively applied out of the box thinking and parts selection along with our requisite high accuracy prep, machining and assembly procedures.
The Foundation
The Block
Since everything is built to go on or in the block, we started there. From the beginning we were concerned about the 273's small bore- things like bore shrouding, air flow and even basic piston availability were major considerations; custom pistons for example can add huge costs to a build. As it turned out, we had little to be concerned about. Here's why: sonic checking the walls on this particular 273 revealed thrust side cylinder wall thicknesses of about .280. Better yet, core shift seemed non-existent on this block because the numbers were consistent from front to back in both banks. If nothing else, this solved our piston selection, material and price issues because we could safely bore the block to stock Chevy 305 size which meant our piston options grew almost exponentially while the price point dropped with the selection and availability of the much more common pistons.
The Crank
Like we mentioned before, this was almost a no brainer. We know from experience the factory forged steel crank can take a beating thanks in part to its robust construction method, material and relatively short overlap. Provided it was in good condition, this would prove a near perfect part of this build. Fortunately, the crank was in beautiful shape. Done.
Rods
Yes, Chrysler's factory forged steel connecting rods can be excellent choices for high performance engines but the reality is that once you factor in the cost of reconditioning, new, forged steel performance rods are a better and more economical choice. We used SCAT I Beam rods.
Pistons
Knowing we were gonna get blown dictated several custom design parameters be built into the pistons which is why we went with custom designed PIE/JE units. Even with the custom design however, the more common bore size kept costs within reason for this type of build.
Camshaft
One of the great things about turbo engines is their excellent street manners vs performance potential. Turbos make great power while offering unmatched drive ability. Getting blown is awesome! With this in mind, we selected a reasonably mild, off the shelf grind from COMP. It specs out with 218/226 Duration @ .050, .525 I/E lift and it's all built on a 114 LSA. This is a cam we knew would make great power in naturally aspirated tune but also make the most of what the turbo has to offer.
Heads
This was almost as much a no brainer as the crankshaft or conrod selections: we went with the EQ Iron Magnum heads. When it comes to bang for the buck these things just can't be beat. EQ's key durability upgrades that addressed the Magnum's short comings combined with an LA style manifold bolt pattern make these heads outstanding, economical performance pieces. The iron construction also make these perfect for power production and long term reliability in a turbo engine. For our part, we added our exclusive Stage One Porting which includes upsized intake valves and flow bench tuning that help unlock even more power potential. Throw in a set of our adjustable roller rockers and this part of the combo is good to go.
Intake
An Edelbrock Super Victor will help handle the deep breathing induction duties. It will be drilled and set up for EFI once we go boosted. Until then (and for dyno testing) we'll use a 700 cfm carb.
Oiling System
A Melling standard volume pump is all we need to keep everything moist. Remember, staying lubed is a very important feature when you're gonna get blown.
Prep, Machining & Assembly
The reality here is that for most people, machining isn't all that interesting and we get that, so we won't bore you with details here except to say that exciting or not, proper machining is critical to an engine build's success or failure on the dyno, the road or the track. Both power production and durability are greatly affected by the quality of the machine work. With this in mind, all you need to know is that we spent painstaking hours, the way we do with every build, inspecting, cleaning, machining and prepping every element of this little 273. From machining and assembly to inspection and cleaning to fanatical detail of each and every tolerance, we checked everything to make sure we didn't miss anything.
Dyno Time
Let's face it, you probably skipped to the dyno sheet before you read anything else. That's cool, we do that too. In that case, you already know the little 273 made 360 bhp and 355 lb-ft of torque. Stout numbers indeed. Naturally aspirated, this works out to about 1.3 bhp per cubic inch which means this little beast is pretty efficient at sucking air, mixing it with fuel, slamming them with spark and blowing the whole combustive cocktail out the exhaust. And it sounds sweet doing it.
So what's next. Well, we think you have a pretty good idea by now. Soon we'll pour on the boost and see how many more horses we let loose. In the meantime though, Chris is getting ready to drop this little bomb into his Dart and drive it as is for a while. We know he's gonna have blast with it but we can't wait to get those turbos installed. Once they're on, the suckin', squeezin, bangin' and blowin' is going to get really good.
This an engine masters 273/292 473 hp at 7,900 rpm
It's got fully ported old school EQ heads
"Hemirunner said:
Stock 273 block 8 sleeves and 3.75 bore for 292 cubic inches
Stock crank
5.4 H-beam Ford rods with EDM pin oiling
Diamond custom pistons with crappy 1/16 ring package
Wet sump oil pan and HV pump with oil crossover
Iron magnum style engine quest heads w/roller rockers, jomar girdles and pushrod oiling
Comp solid roller cam and lifters
Lots better parts today to make way more power"
It's got fully ported old school EQ heads
"Hemirunner said:
Stock 273 block 8 sleeves and 3.75 bore for 292 cubic inches
Stock crank
5.4 H-beam Ford rods with EDM pin oiling
Diamond custom pistons with crappy 1/16 ring package
Wet sump oil pan and HV pump with oil crossover
Iron magnum style engine quest heads w/roller rockers, jomar girdles and pushrod oiling
Comp solid roller cam and lifters
Lots better parts today to make way more power"
Interesting. I read until I saw it was going to be turboed' Hair dryers are cheating!This is I think P.I.E build
The 273 Build That Doesn't Suck
Forget The Little Engine That Could. This Is The Little Engine That Does!
WARNING: Reading this article might cause you to giggle uncontrollably with excitement. It might lead to sleepless nights and neglected work-hours spent planning your own 273 build. It might have you scrounging vintage salvage yards, the classifieds and maybe even strangers' back yards looking for neglected 273 cores. It might even lead you to abandon all rational engine building protocol in the quest to create your own dare-to-be-different scream machine.
We are not responsible for any of this. However, if you choose to build an engine like this, we'll be right there to help you build it.
A few months ago, Chris Sockriter stops into our shop with that glint in his eye and a plan in his head to build a hot 273 for his 69 Dodge Dart. Now if this was 1965 and the 273 was still a serious D/Stock contender, we might have been just as excited as Chris to build this engine, but the fact is, MOPAR's tiniest small block is just that- tiny- and as anyone who builds or has had an engine built for them knows, bigger engines make more power for less money. In other words, why build a 273 for power when you can build a 360 that will make more power for less money? While you're at it, why not build a 408? In comparison, they're even cheaper than 360's when it comes to producing power for pesos.
But like we said, Chris had that glint in his eye, a plan in his head and money in his pocket and all of them were targeted to build the 273. So we kept listening. And that's when things started to get interesting. Turns out Chris didn't just want us to build a hot 273, he wanted us to build one with a hair dryer- aka- a turbo (or two), for some stick-shifted silliness in that Dart we mentioned earlier. Now we started getting that glint in our eye too. This could be fun. Sure, the 273 is still small but throw some turbos at it and it gets quite a bit bigger. Factor in the advantage that Chris already had the engine and that its factory forged crank is plenty tough for boosting and beating and the higher costs generally associated with building small engines might not be so high. So we devised a plan to build a simple, stout, small block that's just a huff-job away from becoming a hero.
Building For Boost
With the plan established that this was going to be a turbo engine, we got to work on prepping and building for boost which in this case, like every case, meant first building a solid and excellent performing naturally aspirated engine. To do this, we spec'd out a package that included a mix of tried and true components along with some creatively applied out of the box thinking and parts selection along with our requisite high accuracy prep, machining and assembly procedures.
The Foundation
The Block
Since everything is built to go on or in the block, we started there. From the beginning we were concerned about the 273's small bore- things like bore shrouding, air flow and even basic piston availability were major considerations; custom pistons for example can add huge costs to a build. As it turned out, we had little to be concerned about. Here's why: sonic checking the walls on this particular 273 revealed thrust side cylinder wall thicknesses of about .280. Better yet, core shift seemed non-existent on this block because the numbers were consistent from front to back in both banks. If nothing else, this solved our piston selection, material and price issues because we could safely bore the block to stock Chevy 305 size which meant our piston options grew almost exponentially while the price point dropped with the selection and availability of the much more common pistons.
The Crank
Like we mentioned before, this was almost a no brainer. We know from experience the factory forged steel crank can take a beating thanks in part to its robust construction method, material and relatively short overlap. Provided it was in good condition, this would prove a near perfect part of this build. Fortunately, the crank was in beautiful shape. Done.
Rods
Yes, Chrysler's factory forged steel connecting rods can be excellent choices for high performance engines but the reality is that once you factor in the cost of reconditioning, new, forged steel performance rods are a better and more economical choice. We used SCAT I Beam rods.
Pistons
Knowing we were gonna get blown dictated several custom design parameters be built into the pistons which is why we went with custom designed PIE/JE units. Even with the custom design however, the more common bore size kept costs within reason for this type of build.
Camshaft
One of the great things about turbo engines is their excellent street manners vs performance potential. Turbos make great power while offering unmatched drive ability. Getting blown is awesome! With this in mind, we selected a reasonably mild, off the shelf grind from COMP. It specs out with 218/226 Duration @ .050, .525 I/E lift and it's all built on a 114 LSA. This is a cam we knew would make great power in naturally aspirated tune but also make the most of what the turbo has to offer.
Heads
This was almost as much a no brainer as the crankshaft or conrod selections: we went with the EQ Iron Magnum heads. When it comes to bang for the buck these things just can't be beat. EQ's key durability upgrades that addressed the Magnum's short comings combined with an LA style manifold bolt pattern make these heads outstanding, economical performance pieces. The iron construction also make these perfect for power production and long term reliability in a turbo engine. For our part, we added our exclusive Stage One Porting which includes upsized intake valves and flow bench tuning that help unlock even more power potential. Throw in a set of our adjustable roller rockers and this part of the combo is good to go.
Intake
An Edelbrock Super Victor will help handle the deep breathing induction duties. It will be drilled and set up for EFI once we go boosted. Until then (and for dyno testing) we'll use a 700 cfm carb.
Oiling System
A Melling standard volume pump is all we need to keep everything moist. Remember, staying lubed is a very important feature when you're gonna get blown.
Prep, Machining & Assembly
The reality here is that for most people, machining isn't all that interesting and we get that, so we won't bore you with details here except to say that exciting or not, proper machining is critical to an engine build's success or failure on the dyno, the road or the track. Both power production and durability are greatly affected by the quality of the machine work. With this in mind, all you need to know is that we spent painstaking hours, the way we do with every build, inspecting, cleaning, machining and prepping every element of this little 273. From machining and assembly to inspection and cleaning to fanatical detail of each and every tolerance, we checked everything to make sure we didn't miss anything.
Dyno Time
Let's face it, you probably skipped to the dyno sheet before you read anything else. That's cool, we do that too. In that case, you already know the little 273 made 360 bhp and 355 lb-ft of torque. Stout numbers indeed. Naturally aspirated, this works out to about 1.3 bhp per cubic inch which means this little beast is pretty efficient at sucking air, mixing it with fuel, slamming them with spark and blowing the whole combustive cocktail out the exhaust. And it sounds sweet doing it.
So what's next. Well, we think you have a pretty good idea by now. Soon we'll pour on the boost and see how many more horses we let loose. In the meantime though, Chris is getting ready to drop this little bomb into his Dart and drive it as is for a while. We know he's gonna have blast with it but we can't wait to get those turbos installed. Once they're on, the suckin', squeezin, bangin' and blowin' is going to get really good.
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