273 build ?????

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DesertRat

DesertRat

Leading edge boomer
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I know nobody builds this motor but I am going to build mine.
Looking through the latest Summit catalouge they have lots of ford & chevy stuff but not much for mopar. I need to know where I can buy some 9.5:1 .030 over pistons for my 273. I think I have the rest of it sussed out but I would like eutectic pistons for this car. (cast would be fine too)
Any advice? DM
 
DesertRat said:
I know nobody builds this motor but I am going to build mine.
Looking through the latest Summit catalouge they have lots of ford & chevy stuff but not much for mopar. I need to know where I can buy some 9.5:1 .030 over pistons for my 273. I think I have the rest of it sussed out but I would like eutectic pistons for this car. (cast would be fine too)
Any advice? DM
Click to expand...
..


273 flat tops are 8.8 to CR. Best way to bump the CR up is either take a little off the heads (.020) amd run the .028 head gasket. Of course it would help to know the deck measurements. I had a stock 2bl 273 and all I did was change head gaskets and it made a world of differance, I could still run mid grade fuel.
 
i got a 273 in my shop i thought abut building one day.i found a company on line called mad dog racing.they carry a master rebuild kit for the 4bbl engine with high compression pistons.ive never ordered any thing from them so i dont know their quality of the products.hope this helps.
 
mygwenevere66 said:
i got a 273 in my shop i thought abut building one day.i found a company on line called mad dog racing.they carry a master rebuild kit for the 4bbl engine with high compression pistons.ive never ordered any thing from them so i dont know their quality of the products.hope this helps.
Click to expand...

Flatlander Racing is a reputable source
 
Thanks fellows, I will deck the block and the heads just enough to true and run the thin head gasket and go with that I guess-------
 
I just got a e-mail message from Phil @ Flatlander yesterday. 273 pistons
are available in your choice of bore size and compression ratio. They need 3-4 week lead time. toolmanmike
 
toolmanmike said:
I just got a e-mail message from Phil @ Flatlander yesterday. 273 pistons
are available in your choice of bore size and compression ratio. They need 3-4 week lead time. toolmanmike
Click to expand...


Those are CP pistons that they use. Saw a set of L2222 TRWs awhile back on e-bay but the auction was pulled.
 
I am in the same predicament. I have a 273 that is being rebuilt. It has the TRW l2222n .030 over pistons in it (from a previous rebuild ). These, I suppose, have 10.5:1 compression like the stock 273 commando did. I want a milder compression ratio for pump gas.
(a)Does anyone know the amount to take off these piston domes to get a good 9.?:1 c.r?
(b)What value do these l2222n pistons have if I sold them and ordered from the above mentioned companies?
(c)Where do I get light wrist pins for the connecting rods (the ones on here are hemi strength but heavy)?
What other mods will help make a dependable yet spunky 273 for me?
 
I was looking for the hi comp pistons for some time and finally came across a set of reg .040's the I'm using. Post them as I'm sure someone will need them. A new set runs in the $400-$500 range. I paid $100 for the ones I got and that was with the rods.
 
Thanks! Anyone have ant suggestions on building the 273. Not trying to go radical, but a bit of umph! would be nice. Looking for dependable, peppy, tire barker.
Thanks!!!!
 
I've been talking to Bobby @ BJR Racing (I hope he doesn't mind me quoting him) LOL Allthough his supplier can't come up with pistons for the 273, Phil at Flatlander Racing has pistons available in any bore size and compression ratio. Allthough I haven't contacted them, Egge Machine has them listed in low and high compression an a selection of bore sizes. The Egge pistons are cast and not forged but I understand the factory HP pistons were cast. I'm sure cast pistons would work just fine for a street motor. Bobby recommended stock intake valve but a 1.60 exhaust valve, bowl blend and gasket matching the intake and exhaust ports. 480-520 lift cam, 228-236 duration @.050 110-112c/l
Bobby has been a great help. Pump gas friendly 9-9 1/2:1 compression would be good for 300 hp or so. toolmanmike
 
Perusing the latest Summit catalouge I found a Summit Branded 4V intake for LA small block that had a small air gap under the carb mount. Went to the website and can't find it. Anyone used this intake yet? I am thinking it would have the runner & port size I want with the advantage of the air gap.
TIA, DM
 
OK the engine decisions are all made but the cam selection.
67 273 original engine built as follows, bored 30 over, valves in
stock heads upgraded to high flow intake & exhaust valves.
9:1 CR with Eddy performer dual plane intake rated @ 5500 RPM
and holly carb with vacume secondaries, TTI headers, balanced & blueprinted.
Pertronix distributor conversion, 904 w/shift kit and 8 1/4 A-Body
3.21/1 ratio shurgrip. I will not put the car on the strip but mostly cruising and street hunting ricers. I am open to either solid lifter cam or hydraulic
and would appreciate input based on this new information.
Cheers! Douglas
 
If it was me? I like to play with the little motors..........

There was a reason the marine, and the higher output 318's, and 273's had single plane intakes. With the small ports, they actually make more low end, and top end form them. Velocity is the key, no need for a dual plane in small port form.

So with that in mind.

I would get an old single plane 273 manifold, torker318, and Holley streetdominator. (All good manifolds, work great with the stock head 273/318)

Then, cam, go solid. Because it is a 273, it will have to rev, or the ricers will eat you for dinner. That said, cam.


390144 ISKY. Bit O lumpitty, runs good in a 318 till like 6K, work great in a 273.

390177 Sounds yummy on the catalogue, never tried it.

Also, on the small port heads, I stay away from cams with too much of a longer ex duration. One, because they make more low end, which is important on the small port engines, and two, because the int/ex flow difference isn't as huge on them. Ditto the bigger EX valve, I have heard that before on the 273's, leaving the intake alone. I think it has to do with the small bore shrouding the bigger intake valve.

Solid Solid Solid. (A quick search, and you will see tons of hyd cam blues, no lifter float, ahhhh, and they sound so cool!)
 
Do you want to use a hydraulic or solid lifter cam? The Isky model E-4 (390144) is a great solid lifter cam with specs a bit bigger than the stock HP 273 cam.

[Tremendous torque & good mid-range power. 9-10.5:1 compr. , good idle stock converter. 3.23-3.70 axle ratio. Up to 625 Carb. RPM-Range (2000-5500) Valve Lift (.425 .425) Valve Lash hot (.015 .015) ADV Duration (260 250) .050 Duration (216 216) LC 108 390144 $132] Flatlander racing


Schneider Cams also has a mild solid lifter cam which is a bit more radical.
It is a horsepower cam at a higher rpm than the E-4 and doesn't have as much torque at lower rpm's. The 273 can build some horsepower at high rpm but torque at low rpm is what you need for the street. Max HP at 6000rpm won't do you much good unless you're leaving every stoplight @ 5500. I have been messing with my desktop dyno and have found the E-4 to be the best balanced 273 street cam.
Schneider #14202 Mild idle. 1500 - 5000 RPM. 132F 264 224 .480" .014" 110 44285 $165

With the variables I used for the dyno program, the E-4 produced
322 HP@ 6000 rpm and 322 lb/ft@4500rpm. The #14202 produced
337 hp@ 6000 rpm and 309 lb/ft@5000rpm. (more HP but less torque) Between idle and 4000 rpm is where your engine spends most of its time on the street. Comparing specs at 2000 rpm the E-4 wins hands down.
E-4 97 hp @ 2000 rpm and 254 lb/ft of torque
#14202 80 hp @ 2000 rpm and 211 lp/ft of torque

The E-4, a dual plane intake, headers, and free flowing exhaust should get you easily 300+ hp @ the flywheel and more torque than what I listed above.
(I was using a stock open plenum intake and stock exhaust manifolds with mufflers for my comparison.) Click this link and hear what the E-4 sounds like in MVRCorp's 67 Dart. Scroll down to post #12
http://www.forabodiesonly.com/mopar/showthread.php?p=633373#post633373

I guess the bottom line is you don't have to go too wild to get usable torque and HP (usable is the key word) If you want to go racing or get real radical then use the big cams with the big $$$'s to make it all work. Give me a few minutes and I will run your variables and see what numbers we get..

toolmanmike
 
With your combo I got:

E-4 114 hp and 300 lb/ft both @ 2000 rpm
325 hp@ 5500 rpm and 332 lb/ft @ 4000 rpm

#14202 99 hp and 260 lb/ft both at 2000 rpm
341 hp @ 6000 rpm and 321 lb/ft @ 5000 rpm

As you can see the #14202 has more peak hp at a higher (6000) rpm but the E-4 starts out with more hp and torque and has more peak torque at a lower
(usable) rpm. Hope this helps and thank MRVCorp for the video and the great sound of the Isky cam. That's the cam I'll install when I rebuild this winter.
toolmanmike
 
I hoped you wouldn't mind. You have been much help to us all. Thanks.
toolmanmike
 
Me too. I read through my response and wondered if anybody could understand
what I typed. LOL toolman
 
That and the peak HP and torque being the same 2Krpm apart........

Bewildering.

That clip did sound nice tho. Notice he has the single plane intake too. I love that manifold, doing some carving, and a plate, and a 500cfm 2bbl Holley works wonders.

I have a single plane 4bbl on my boat (small port iron), on the 360 It has I keep eyeballing...... thinking of pulling it off and putting a Dual port on it, since it runs 1/4 throttle for hours, try to get some more HPG's out of it. That single plane sure looks sexy to me........ Kinda wanting to build a 273 solid single plane for the ramcharger, mild as can be, and see if I can break the 20MPG with it.
 
The E-4 has a pretty flat torque curve. It's an old school cam but it works.
The 273 can't handle much of a cam because of it's small size. The more the cubes the bigger cam you can run. A 268/485 cam in a 273 would be big. I put one in my 454 in my tool truck and it sounded like a stocker. toolman
 
I have used the E-4 in 318's, love the power. Sure is a difference between the solid and the mech when it comes to RPM ceiling.
 
I've said this before, but be certain to cc the heads and calculate compression using the deck hight of the pistons.

My 65 273 had new .030 over flat tops in it when I got it. With the pistons down .045 and the head cc of 65 it calculated to 7.8 to 1. I had no money for new pistons so I milled the block .040 cut the heads .032 and used the .040 gasket I had. It now is at 8.9 to one. Ideally I would have gotten dome pistons, had good quench and just under 10 to 1.
Those little engines run on pump premium fine with that much compression.
I run 87 in mine with 35 degrees total timing and have never heard it ping.
I also have the comp 270s solid. With [email protected] and 468 lift before the .022 lash. Its a good cam, is ok until 3,000 rpm, then she wakes up.
Its a snappy engine and gets about 20 mpg on the freeway. It had highway gears, I just put in an 8 3/4 with 3.55's but have not driven it yet. Need to shorten the drive shaft. I know it will make a huge difference.

Heres the build if interested.

65 Barracuda
1965 273
8.9 to 1
Pocket ported closed chambered heads.
Stock valves
270 solid, 224 @ .050, 468 lift. Lash .022=446 lift
balanced
windage tray
65 273 single plane with 600 Carter carb.
Factory 273 exhaust manifolds
2.5 inch single exhaust with a chambered muffler
Automatic, and now 3.55's. I know the lower gears will make a substantial difference off the line.
It moves pretty good for a little engine. Once it hits about 3k she pulls good to 6k. But I still want more power. It was a budget build with parts I had. All I had to pay for was the crank grinding, balance, rings and bearings. All the other parts were collected over the last few years from random sources I found cheap with no particular plans for them. I worked at a shop and did the heads and block myself. Its fun, and runs great. But That 360 I have in the corner will eventually need a new home.
 
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