Critique/suggestions on 273 engine build

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64physhy

64physhy

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First off, I know many of you will say to just get a 360, but I want to build the 273. The engine only has maybe 4000 miles on a rebuild. It was rebuilt with a mild cam by the PO and has an Offy intake and Edelbrock 600CFM carb and electronic ignition. My goal is to get 300-350 HP/TQ on a budget. Here's my ideas:
Comp Cams XS268S (.488"/.501" 230*/236* @.050) or
Comp Cams XS274S (.502"/.511" 236*/242* @.050)
KB or TRW flat top pistons
Mill heads to 52-54cc
Port heads
650CFM carb (Edelbrock?)
Headers (TTI or Spitfire)

I want to stick with the intake I have to save cost. It's in a '64 Barracuda, but the heads are from a '66 Commando, so have the later intake manifold bolt angles. Does this look like a good combo? Any Suggestions? (remember, it's a budget build) Estimates on the power this would make?
 
Why are some 273 owners so dang hardheaded ? The Commando things ma mopar did with that engine were more cosmetic than performance.
I own 2 of them. Running standard 273 2brl and a Commando engine to rebuild but I dont plan to burn rubber with either of them.
As for the budget factor, anything you do to a 273 will cost as much or more than the suggested 360. You'll be lucky to get past 300 hp with the 273. I wouldn't expect it to live as long as a mildly built 360 either.
If Paul Barker ( local ) was still living he could sit here in my chair and tell you about milling 60 thou off those heads only to have them crack again and again. I doubt it would change your mind though. Good luck
 
Having rebuilt a 273 once already, I'd tell you again I would NOT do another one. 318 much cheaper and easier to find parts for, plus more inches.
 
A long time ago (1974) I poured money into my 273. Headers, high compression pistons, Offy manifold, Holley carb, street hemi profile cam, Isky Valve springs, windage tray, dual point distributor, etc. because that was the engine I had. It was a screamer for what it was, & I had a lot of fun with it, but a decent 340 or 360 would have walked away from it. If I were you, I'd start with a 318 at the least.

Since you have the engine already, I suggest the headers, something to bump compression (pistons would be better than head milling but they're probably next to impossible to find, maybe EGGE's has them?) & a mild cam, maybe one of those you mentioned. But be very careful with your cam selection. The 273 doesn't make a lot of torque, which is what you really want on a street engine unless you plan to add gears & wind it up. I ran 3.91 gears too. My engine saw at least 7,000 rpm once & never seemed to suffer from it.
 
Like Redfish, I've been through a 2 bbl and 4 bbl 273. The 4 bbl revved great and made wonderful sounds through the factory exhaust. Both engines were soft on torque on the bottom end. The 4 bbl woke up when you crossed 2500 rpm. The 2 bbl engine had flat top pistons, the 4 bbl had nice domes with valve reliefs in them.
I could do the same thing with a 318 with better low end torque and without having to sweat bolt angles or trying to find domed pistons to get the compression level where the 273-4 s were.
Consider that the D/Dart engine produced 275 hp with all of the expertise Mopar had in 1966. (Dealer bulletin included below). In light of this, the goal of 300-350 from a 273 with flat top pistons is unrealistic on a budget rebuild. Your cams are going to need a lot of compression and a lot of rear gear to get the full benefit. If it's going to be a street car, it will need to be able to run on commercially available, 93 octane unleaded.
The changes made by the PO that you like could be used on a 318 with no problems. Same for a 360, but I'd want to go to an intake with ports made for the larger ports on the 360. I also would probably not transplant the cam and lifters from the 273 to another engine.

Dodge Offers "D" Stock Dart

DETROIT -- A new 275-h.p. Dodge Dart GT that meets D Stock specifications of the NHRA, AHRA and NASCAR is now in production. The "D/Dart" has a shipping weight of 2,946 pounds.

The "D/Dart" features a modified 273-cubic inch engine with a special four-barrel Holley carburetor. Other features include:

A special Camcraft camshaft (284 degrees with .495 intake and .505 exhaust), Racer Brown valve springs, a modified, full-breathing intake manifold, a
low-restriction air cleaner, and a Weber clutch. Other standard items are: a heavy-duty 4.86:1 Sure-Grip 8-3/4 inch rear axle, free-flow exhaust headers by Doug of California, a four-speed manual transmission, heavy-duty suspension, and 6.95x14 B.S.W. tires.

The "D/Darts" are regular production line automobiles.

Additionally certain, basic service parts will be available through the Chrysler Parts Division, so that owners of earlier Darts may convert from the 235-h.p. to the new 275-h.p. version of the 273 V-8 engine.

The "D/Dart" has been certified by the sanctioning agencies in the D Stock class. It is expected that this car, properly prepared, will be a top contender.

A high idle speed minimizes roughness, a high numerical axle ratio is used for top acceleration, the distributor is modified for quick advance, and the ignition system is designed for optimum engine output. Due to the expected use of these vehicles, no warranty coverage applies.

Those who are interested in more specific technical details on this car may contact staff engineer Dick Maxwell, Product Planning, Chrysler Corporation, 341 Massachusetts Ave., Detroit 31, Michigan. Phone 313-883-4500, ext. 3947.

In case your local Dodge dealer does not have a full list of the part numbers for these specific components you may wish to contact performance parts specialist Ray Ryder, Chrysler Parts Division, 22631 Lawrence Avenue, Centerline, Michigan. Phone 313-539-3000, ext. 7763
 
I was originally going to get a 318 and build it. I just thought that since this engine has a fairly fresh rebuild, I won't have to worry about rebuilding the bottom end. If I get a 318 (or anything else), chances are, I'll have to start from scratch and do a full rebuild, unless I find someone selling one that's already rebuilt for a decent price. I'm looking to get about 9.5:1 or 10:1 compression. I have an 8 3/4 with 3.23 gears (one legged) that I'm going to put in it. I know I'd need lower gears to get any kind of torque to the ground, but I'm just going for a mild street machine for now. The headers are the most expensive part of what I want to do. Cam, springs, locks, seals cost about $225, flat top pistons are around $200-250, the headwork would probably be around $300-400, new carb around $500, but I'm sure I could find a used one for a lot less, then the Headers-TTI at around $700, or spitfire for a lot less (but would require converting to manual steering which is more $$).
I would RATHER have a 340 or 360 with a lot more power than I'm going for here, but I've decided to work with what I've got due to cost.
 
If cost is a concern, sell the 273, and buy a 360. Your piston choice alone will cost more that a running 360.Plus milling heads,buying cam......a STOCK 360 with a 4 barrel and headers will be way ahead, and much cheaper. If you want to use the 273, just stick it in, and live with it. You will never be happy with it's power, unless you spend BIG bucks. I understand your sentiments about using the 273, and respect that, but you did say you want more power, right?
 
64physhy said:
I was originally going to get a 318 and build it. I just thought that since this engine has a fairly fresh rebuild, I won't have to worry about rebuilding the bottom end. If I get a 318 (or anything else), chances are, I'll have to start from scratch and do a full rebuild, unless I find someone selling one that's already rebuilt for a decent price. I'm looking to get about 9.5:1 or 10:1 compression. I have an 8 3/4 with 3.23 gears (one legged) that I'm going to put in it. I know I'd need lower gears to get any kind of torque to the ground, but I'm just going for a mild street machine for now. The headers are the most expensive part of what I want to do. Cam, springs, locks, seals cost about $225, flat top pistons are around $200-250, the headwork would probably be around $300-400, new carb around $500, but I'm sure I could find a used one for a lot less, then the Headers-TTI at around $700, or spitfire for a lot less (but would require converting to manual steering which is more $$).
I would RATHER have a 340 or 360 with a lot more power than I'm going for here, but I've decided to work with what I've got due to cost.
Click to expand...

Listen.... I was trying to be nice:toothy10: since you stated "I know everyone is going to say go with a 360" but I think everyone else has expalined.

I've tried the 273 route before as a power builder and yes the the motor came with the car. Click on my username go to my threads I created.. you will the plees for help on making power with a 273... everyone is right believe me ... don't sink another penny in that motor!!! I gave my entire 273 motor away!!

360s have longer stroke cranks...

Save your money while you still have it in your pockets...


I have a pretty mild 360 (compared to other members motors) and love it yes it was extra money I know... but I love it!

Here is what I think of the 273 :thebirdm:
 
318 would be my choice - your heads will work with some larger valves (1.88/1.60's), and they are already closed chamber, if they are truly 66's. You can also reuse the crank - most 273's had forged cranks which can be balanced easily for a 318 or 340 for that matter. 273 pistons used an insanely heavy walled wrist pin to make up the bob weight for the crank, I suspect the original cranks were used in semi hemi 318's which would explain the insane wrist pins.

I'd pull it apart and see what you have and then reuse a bunch of the internals inside a late model 318 engine. If you get a hyd roller motor block then your cam options become even more interesting. Consider putting a hot rod roller hyd cam in it. They make tons of torque if chosen correctly. You can reuse the intake and carb as well - so you've got alot of the pieces already sitting inside or on the 273. What you'd need is a set of pistons and rods and a good core block, and valve train parts. Go grab a 318 from a late 80's dippy or truck and do it to it. If you use some stock off the shelf pistons you can get close to 9 or 9.5 to one using thin head gaskets. You can easily meet the 300 hp level with a modest cam and some well chosen parts. Plus a 318 looks exactly the same as a 273, no changes to engine mounts or anything, and if automatic or manual for that matter it will bolt directly to it with no other changes either.
 
IF you could get an honest 350hp from a 273, it would be a PIG on the street. It would need 5.38 gears and a tiny convertor or 4 speed and would have a very narrow powerband. Gee, you could get that with a junkyard 360 with a cam and a little head work(and I do mean little). Chivalry is dead, embrace the modern days.
 
Ok. Thank you all for your comments. Looks like I'll hold off on the engine for now and maybe get something bigger later on down the road. For now, I'll just work on getting that 8 3/4 put in and getting it ready for power. See, if I go with a bigger motor, I'm going for a lot more power than 300-350.
 
64physhy said:
Ok. Thank you all for your comments. Looks like I'll hold off on the engine for now and maybe get something bigger later on down the road. For now, I'll just work on getting that 8 3/4 put in and getting it ready for power. See, if I go with a bigger motor, I'm going for a lot more power than 300-350.
Click to expand...


Now you're on the right track. :cheers:
 
66dartgt said:
Plus a 318 looks exactly the same as a 273, no changes to engine mounts or anything, and if automatic or manual for that matter it will bolt directly to it with no other changes either.
Click to expand...

Does this apply to a 65 cuda with original 2bbl 273 and floor shift auto?
If so, when the time comes it would be a no brainer for me to ditch the 273 too.
 
kcoyle - a later 318 will look very similar to a 65 273. The main difference would be the angle of the intake bolts. on a 65 motor, the bolts go into the heads vertically, on a 66 or later engine they go in at an angle perpendicular to the side of the heads. More or less parallel to the deck of the block. To answer your question the later 318 will bolt up perfectly to your cable shifted automatic. The only thing needed is an adapter ring for the crank register on the torque converter. A simple ring of metal is all thats needed. If you know someone that has a metal lathe they can turn one down for you in short order. I think there used to be an outfit called wildcat auto parts located in Washington state that has these adapter rings as well. google them or do a search on this site for them.
 
Not bashing your plans, add me to the list of previous 273 owners, but I added up your prices on the parts you want to use... they came to almost $2000 on the low end... That's a used low mileage small block or a possible new short block,(read 360). Reuse your heads and intake, save for the B&M flexplate and schumacher mounts. If you're set on the 273, keep the cam at 268-272 duration max. Consider hooker part#5208 headers, they work with pwr steering, have them on my 64 Dart. The horsepower level you want is possible if you spin it hard, but the tq level isn't... Remember torque moves the car..
Doing the rear first is a good idea..

Bob
 
BobsDart said:
Not bashing your plans, add me to the list of previous 273 owners, but I added up your prices on the parts you want to use... they came to almost $2000 on the low end... That's a used low mileage small block or a possible new short block,(read 360). Reuse your heads and intake, save for the B&M flexplate and schumacher mounts. If you're set on the 273, keep the cam at 268-272 duration max. Consider hooker part#5208 headers, they work with pwr steering, have them on my 64 Dart. The horsepower level you want is possible if you spin it hard, but the tq level isn't... Remember torque moves the car..
Doing the rear first is a good idea..

Bob
Click to expand...

I've pretty much abandoned the idea. I'm looking for a lower geared (3.55-3.91) rear end chunk (I have an 8 3/4 that's not installed yet) that I'll put in it first. I'll also probably get some headers. That way, when I do get a more powerful engine, I'll have a rear end that can handle it and will already have the headers. Do you have to cut the inner fender out for those Hookers, or are they the ones that hang low? I thought TTI were the only ones that you don't have to cut the fenders, and they stay tucked up tight under the car.
 
You do have to cut the inner fenders, but not as large as they say. TTI's wern't around when I did my car. I've never had ground clearance problem, but the tires do rub under full turn, usually when parking...and you can use a regular mini starter and not their $200+ one!!!
Here's a few top side pix.

Bob

020.jpg


022.jpg
 
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