Building out a 273 recommendations

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cudajames

cudajames

FABO Gold Member
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Hello,

I just recently bought a 1966 Barracuda with a standard 273. It was suppose to be a commando, but was misrepresented by the seller (reimbursed me some $$)
I plan to pour about 7 to 8k into the car, more for reliability (first classic with wife and kids). I do want some performance. I would have been happy with 235hp or a little higher but . . .
The PO did install an edelbrock manifold and a small 4bbl (500cfl) (to his mind, this made it a commando)
Anyway, I am thinking about upgrading the cam (a purple cam from summit 284/284 duration and 484/484 lift) and a couple other features (larger carb, 600-700 on the 273) and wanted to ask your advice, recommendations and experience.

The body and interior are super nice. So the car is a keeper even if the motor wasn’t quite what it was suppose to be. My goal is a nice classic car with some pep, not a true hot rod. So sub-300hp is fine. I prefer mid-250s

Again I am working toward a classic with some get up and goooo

thank you for any help and advice

james
 
If the 500 cfm carb is in good working conditions it's more than fine for a mild 273, that cam is way to big on the summit site says 2600-6000 rpm range but in a 273 it would be more likely 3600-7000 rpm range.

Probably want something more in the 260 ish cam size
 
The bigger cam and carb will work well with a 408, but not for a 273. I had a 500cfm on a 289 for the life of the motor and it was fine with its small cam.

How about fixing the single master cylinder and front disc brakes?
Maybe a HEI conversion and upgrade of wiring?
 
Check out my build link. I rebuilt my Power Pack 273 with a Isky E4 cam. It's no tire scorcher but it runs well. tmm
 
Looking at different cams now

Between 280 duration with a 474/474 lift with operating rpm 2000 to 6000
or a softer 260 duration with 430/450 lift with operating rpm 1200 to 5200
 
you will probably want to trade the 3 speed for a 4.
where (rpm) you want to find your power will have a lot to do with with what cam you go with. lots of real life experience here on FABO for sure, you can also visit with the cam co you will use and they can give some good advice, remember the 273 head will obviously affect power. there's a reason people hunt the 340!?? but still the 273 is great little motor no doubt.
 
cudajames said:
Looking at different cams now

Between 280 duration with a 474/474 lift with operating rpm 2000 to 6000
or a softer 260 duration with 430/450 lift with operating rpm 1200 to 5200
Click to expand...

The power bands given by cam company's are more than likely based on 340/360 so move those power bands up a bout 1000 rpms so 3000-7000 and 2200-6200

First figure how much rear gear your willing to live with before deciding on a cam, For a performance 273 the lowest I'd go is 3.91.
 
Just a thought, If your budget is $7-8,000 you will need to shop wisely. I spent $3 on my 273 and paint and body work here in the Midwest is at least $5,000. There goes my budget and prices in Cali are higher I would think. If your 273 runs well and doesn't blow lot's of blue out the tail pipe you might want to leave it as is mechanically and put a electronic ign. kit in the distributor and re-curve it. If you go too far overboard with the engine it always leads to other parts to make it all work. Headers and good exhaust are well over $1000 and of course you will need a different transmission and shifter as well as a heavier rear end. There's more $$$$'s tmm
 
toolmanmike said:
Just a thought, If your budget is $7-8,000 you will need to shop wisely. I spent $3 on my 273 and paint and body work here in the Midwest is at least $5,000. There goes my budget and prices in Cali are higher I would think. If your 273 runs well and doesn't blow lot's of blue out the tail pipe you might want to leave it as is mechanically and put a electronic ign. kit in the distributor and re-curve it. If you go too far overboard with the engine it always leads to other parts to make it all work. Headers and good exhaust are well over $1000 and of course you will need a different transmission and shifter as well as a heavier rear end. There's more $$$$'s tmm
Click to expand...

Good advice here. Once you tweak one thing,other parts & systems need massaging. Costs add quickly.
 
You will defiantly have to check out the gears in the diff, My 65 Cuda had 2:93's in it and even with the 4 sp it felt like a dog. I went to 3:23 's and it's like I gained 50 hp. 3:55 would likely be ideal for you. I think the 7 1/4 will hold up for you , as I ran my 340 with the 7 1/4 and only killed the rear with the 14" slicks.

Go with the small cam, (260) TTI headers and duals, and leave the 500 cfm carb. recurve a good electronic ign dist. I think you'll be surprised by the power.
 
I'll agree with the rear gears, my Valiant IIRC had 2:56 gears in it. with the 225 the gas pedal was used as a on off switch. 3:23 would be a minimum for ya.

You could also step up to some 318 heads although you wouldn't be able to use your existing intake, use softer cam, The TTI exhaust with Duals will run 1400.00 alone, not sure if that's where you want to spend your money.
 
Working on my sister-in-laws 66 Barracuda I installed 3.27 gears and TTI 2.5 inch duals with X-pipe and stock manifolds. I think that a good 2.25 single exhaust would have been better. Also installed 340 and sub frame connectors from US Car Tool. Should be getting it ready to finish this year.
 
Like was said - concentrate elsewhere unless the drivetrain is coming out for a full resto deal. Keep the cam smaller. Under 220° @ .050 and i always liked the sound of a solid flat tappet cam... Add a decent exhaust which on that car means a well build Y pipe, and something like 2 1/4 or 2 1/2" pipe to the back with a decent muffler on it. I'm not a fan of duals on these cars but that's another choice. Gearing you're fine. Transmission you're fine assuming this is a cruiser car and not a racer.
 
I Built my 273 3 or 4 years ago now. $1200 in machine work which included a turned crank, .030 over bore, cam bearing install, as well as full balancing ( replaced number 6 rod), plus a valve job, valve spring test, etc. Clevite bearings, felpro gaskets, and lots of lube. TOTAL cost of the rebuild all added up, with all the little parts for me was about 2500 including a new clutch kit amd the paint. But I did all the cleaning and assembly after the machine shop worked it.

TOOLMANMIKES Thread: http://www.forabodiesonly.com/mopar/showthread.php?t=94343

My build thread: http://www.forabodiesonly.com/mopar/showthread.php?t=87413

My install thread: http://www.forabodiesonly.com/mopar/showthread.php?t=132062

For a non hi po engine, valve springs are gonna be weaker than u want, so plan to replace those when u buy the cam.
 
If it's not a Commando, it's a low compression motor. You may be wasting your time with big cams if you don't have any compression to start with. Think about it -- more duration means overlap means more bleed off.

I don't know if I'd waste my time building an 8.8:1 (nominally, probably less than 8.5:1), small inch motor. Just not much potential there. Unless you turbocharge it...
 
Hey James what part of San Jose are you in ?

If anything is ditch the 273 if it not the original commando for a 360 .theyre everywhere . And produce good power with little work and cost .
 
If you put in a big cam and bigger carb, it will be almost un-driveable unless you constantly rev the motor. Lots of valve overlap gives the stumbly "race car" sound that many prefer but also pours out noxious fumes and gives terrible mileage. The Tesla drivers in Silicon Valley will sneer at you.

In my 1965 273 (originally 2 bbl), I put a hydraulic "RV/Torquer" cam (0.422"/0.440" lift), which is a bit bigger than the Commando cam, and Rhoads leak-down lifters so it idles smooth. I don't like adjusting valves. I get enough of that with my M-B diesels. I used shorter "340 TA" ball & cup pushrods.

I 3rd the suggestion to lose the points. You can get a new HEI distributor for $45 on ebay, plus a $20 e-core coil. Some install a 72+ Mopar ignition, but that is much more effort, and usually much more expensive, plus an older design (requires a ballast).
 
Work to start Monday. Everybody thank you for all the help and pointing out that I need more education.
Going with a mild comp cam, higher compression pistons with a full engine rebuild and balance. Which will include electronic ignition and a tweak to the exhaust pipe. Performing some other work as well, new gas tank and rebuilding the front end. (Yes, increased the budget a little)

Should be done in time for the Goodguys May 31st Show in Northern California
 
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