Need A Recipe For A 273 Rebuild

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Be VERY careful when camming a 273 engine. It's exactly the oppisite of a stroker that eats up duration. A big cam in a 273 will kill it for street use. Think about how a 360 runs with a xe268H and then take 1/4 of the displacement away. Won't run the same or even close. It would be like putting a 292H or 305H cam in the 360.

I'd think a std 340 cam would be as big as you'd want to go for a street engine.
 
I have found by FACT not theory that a Erson .420/.420 lift is a great cam for a 273 but the Summit .441/.441 opens the door a bit up in the RPM range. I have tried both cams on a .060 273 and that's what I have found. Now I tried the purpleshaft .474/.474 cam also and that was to big for the 273. I run that cam in my 360 and have 419lbs of torque and is around the 400hp mark.
 
I say way to go build the little 273 there high revers.Use the 273 commanda pistons and a repo soild-lift cam and 4brrl. you should be happy.A couple years ago i was talking to a older guy about his 65 dart 273 hipo 4-speed 4? somthing gears.He said in 66 he held a S?Stock record with it 12 85 then he got drafted never raced again but keeps the car for mermorys
 
Does anyone sell pistons for the 273 or are they all custom parts now ?
 
I've done the 273-360 swap in my 64 Dart. No comparison!!! You can rev the 273 higher but low end grunt is not there. I did the cam swap in the 273, stay with a 268-270 max duration cam. The repo 340 cam works great in that and a 318... Dual plane intake a must also...

Bob
 
Thanks MR318. PoisonDart and I were just looking for suggestions from those
who have built 273's before. I'm not looking to build a 273 to drag race or even street race. I just want a clean overhaul and a little more performance.
I could put in a 360 or build a stroker but I choose not to. I like my 273 and that's what I'm going to build. toolmanmike
 
Adam, you can get allmost everything you need from Egge Machine.
 
Me too but I dont want to Hijack the thread anymore. Lets get back on track.
 
Hey Poisondart64, I just got done doing a 2-bbl 273 in a 67 Barracuda rag-top. We did a Formula S clone out of it. The mods that I did to the engine brought it to life. The owner loves it and told me that the first time he drove it home, he knew right away that it had alot more power. Send me an email and I'll give you more details. And I used the Summit cam that Mullinax95 suggested.

Ken
Edison, NJ
[email protected]
 
What is this nazi germany? joke.
Ok, with out insults, I recommend the MP.490 276*[.460 lift after lash]
10-1 pistons a dual plane, headers, and good rod bolts, and use the lil 273-318 floating rods. thats just what I recommend.
I'm just reposting what was deleted, that is p.c of corse.
Do whatever you want , just have fun learning while your doing it.
 
Guys I had a very nasty 273 in my 64 Dart, owner the car since 73 and it has gone from stock to a factory type 235 HP 273 to a D dart spec and eventually ended up at a 275 HP to the rear wheel which factored out to about 340 at the crank. I ran low 13's with a 4.10 and a 727. Had to spin it 8k to make that kind of power. The 273 will loose torque fast as posted early in this thread if you go long on cam duartion.

The key is fairly high compression, lots of initial spark timing and a high lift short duration, low overlap cam. Even if it is a street 230-250 hp at the crank engine. Sire a 318, 360 make more HP T etc. But if you want to keep the 273 get a custom set of pistons in the 10 range and cam like 480-515 lift max for street. 625 Carter, or Holley is enough omn a modiified 2 plane to act like a torquer, decent headers and a 2 or 2 1/2" ex is plenty. Do a bowl cleanup job on the heads, port match the intake, do a great 3 or 4 angle valve job, back cut the valves etc. , if you have the money replace the guides and go taller valves with smaller stems spring seats etc. If you go oversize valves shrouding is an issue. I have the origional Mopar bible from 78-79 and I am telling you high 13's even on todays crappy fuel is obtainable in a street car that is not to wild.

You can get it into the low 13, high 12s in an A body but then it is more a race/bracket car. You can do at a decent price a 230-260 HP engine, only gotcha is the custom pistons. I think I priced a set of Ross pistons for like $600 a set. When you go custom you are gonna do forged since:
#1 you need to spin the think 6500-7500 anyway to make peak power
#2 the cast custom are about the same price when you do custom sets.

I used a forged 318-3 truck crank back in thr day, windage tray modifed steel rods etc but a 340 unit crank if you can find one would be a plus, and also you have to outway the money to rebuild the rods, high strenght bolts etc or just get a set of Eagles, Do a good balance job (A MUST)

Anyway you can make it run. I did and I even ran circle track at the old Ontario 500 speedway.. Dam I am old huh!

I now run a 416 with over 500 HP now in the Dart and the Torque and throttle responce is amazing! No substitution for inches...

Wish they had a 360 or a stroker back in the day. Largest option was a 340 or a 318.. 360s were $$$ and had just come out when I was building the car 1st go around.

Good luck have fun, and determine how much MONEY you want to spend, this is the real key... Hell I know a gus tht ran 10s in a 65 Valiant with a 273. PS He was spinning that 273 9k and no it was not a street car, neither was mine, even though I did take it out at times...

lso did not mention above but if you want it quick you need 3.91 + gears a loose convertor at 3k stall or more, and or a 4sped with a 10 1/2 or 11" clutch. Dont waste time on the little 9 1/2 " clutch. You will fry them up. I did 18 times in 3 years.
 
Thanks for the info Dyno Dave. Thats the kind of stuff were looking for.
toolman
 
Very good info Dave.
You nailed it.
I was saving my opion till I knew what he was doing with the car.
For a street motor I'd use all the lift you can safely do with the
valve train your using.
Go shorter on duration.
The pistons don't hang around TDC very long and the valves need
to close early to build cyl. pressure
I'd massage the heads and manifold lightly taking a lot of time to
unshroud the intake valves.
What ever you do a 3.91 and 3500 stall will work great.
If you want to go above 6 grand everything changes.
Fan blades, pumps and altenators have a terrible time
at that speed and tend to come unglued.
You'll be very suprised how fast the thing will rev to 6 anyway!

This guy has a lot of info:

http://victorylibrary.com/mopar/chamber-tech-c.htm

http://victorylibrary.com/mopar/mopar-tech.htm
 
Here is the engine combo I was considering with my 273 until I decided to go bigger. I ran these numbers through DeskTop Dyno and was pleased with the results. Probably would need an higher stall torque converter and 3.55 or higher gears.

273 block, 3.31 stroke X 3.665 bore (0.030 over) = 277.8 ci.

302 heads, 1.78 intake, 1.50 exhaust, ported and using flow numbers provided by BJR Racing. Gasket matched to intake.

Heads shaved to get 9:1 CR with flat top pistons and quench distance of 0.040.

500 cfm carb.

Small tube headers with mufflers.

Comp Cams XE268H cam.

Here is the predicted output with different intake manifolds

Dual plane high torque ( I assume this would be a small runner intake designed for a 318 )
330 HP @ 6000 RPM
355 lb-ft @ 3500 RPM

Dual plane high flow ( I assumed this would be a large runner RPM Air Gap designed for a 340/360 )
354 HP @ 6500 RPM
342 lb-ft @ 4500 RPM

Single plane high flow ( I assumed this would be a large runner modern single plane for a 340/360 )
382 HP @ 6500 RPM
355 lb-ft @ 4500-5000 RPM
 
Egge Machine has about anything you need for the HP273. The pistons are
$340 a set and come in std, .020 .030 .040, and.060. Mike
 
Yep there are several pistons, but keep in mind the quality and weight. I think the Ross units are better and weigh less. Like I said I would lean toqwards forged if you are gonna spend that kind of money and you will need to spink 65500 + to make any real power to speak of and gear it accordingly.

I can post you some details on cam etc that works in several applications.

PS I even tested back inthe day the mopar cams from a 340 and the 260, 272, and I think the 280 grinds. These were back when they did the purple series cams. All were slugs on the bottom end and torque curve was flat but very unimpressive too.
 
The Ross pistons are very high quality and would be mandatory to build a race engine. Poisondart & I were thinking along the lines of rebuilding our engines and "kick it up a notch" so to speak by using a slightly bigger camshaft and some head work. Headers would be a matter of chioce but if we use stock type manifolds we at least need some kind of HP exhaust. We are looking to see around 300 hp and it shouldn't be too hard to get there with basic stock HP273 parts. There's allways bigger, lighter, better but we don't want to go there.. I would use lightweight Ross pistons if I was building an aluminum rod, roller cam motor with 13.5:1 compression that would turn 10 grand. For the extra dollars spent, I'd put my money in the heads. Thanks for all the info. toolmanmike
 
Hard to beat cubic inches.
Especially when you want torque to move from a dead stop.

Thats why when I had to replace or rebuild my tired 273,
I went with and rebuilt the 318 .


Heck look at the stock 318 2bbl vs 273 2bbl torque specs for 1967.

340 lbs torque vs 260, {Or 280 tq with the 4bbl 273}.


V8-273 2-bbl 3.625 x 3.31 8.8:1 180 @ 4200 260 @ 1600 40-65
V8-273 4-bbl 3.625 x 3.31 10.5:1 235 @ 5200 280 @ 4000 40-65
V8-318 2-bbl 3.91 x 3.31 9.2:1 230 @ 4400 340 @ 2400 45-65


http://www.mymopar.com/enginespecs.htm
 
Like I've said on other posts. I respect what you-all do with the engines in your cars and I hope you respect that I choose to keep the HP273 in mine. I will agree, it is small and probably under powered compared to your 400 HP 318's and the rest but with all it's got going for it, it demands a certain amount of respect. Lets keep this post alive with positive 273 info. thanks, toolman
 
My 273 is a factory Commando. I reused the orginal pistons and sleeved some cylinders. You can get a new set of oversized 10.5 to 1 pistons through Egge.com, but they are expensive. Finding a old set of pistons and sleeving the block will save a lot and give you a stronger engine, since sleeves are steel vs. iron you will get much less wear down the road. I polished and balanced the rods. The steel crank was polished and new bearings installed. Bearing are the same for the 318, so lots of choices. New I use a set of 85 318 heads (302 casting, swirlports). I bought mine already ported and polished. Followed up with a hyd 340 replacement MP cam. Sorry, I can't recall the specs at the moment. I had planned to use a edelbrock performer intake and a 500 cfm carter. The intake had a issue with my factory A/C stuff. If it wasn't for A/C it would have been fine. last is a set of spitfire headers. Dakota magnum manifolds will do the trick too and look more stock.

Just to defend the 273 a little. The only expensive part is the pistons. All other parts will have the same cost as a 318/340/360, but none will get the fuel savings as a 273 and face it, no one gets excited over a 318 or a mild 360, but have a 273 or 340 and watch the reactions and stories you will hear from back in the day.
 
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