Upgrades to my stock 273 67 Dart GT

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Redhelmet

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Hey everyone,

I am looking for info/advice on upgrades for my stock 273 dart GT. This is my current daily driver, however, I want to make the car more lively and powerful without going too far obviously as mileage and reliability are important. I have had issues recently with stalling/and or vapor lock once the car is hot and at idle. Had a couple mechanics say my carb needs a rebuild as well. (This is/was my first car and I'm learning). I would rather put money/energy into a 4 barrel carb/intake upgrade first for this reason.

So firstly I have been searching on the forums and come to the conclusions that my options for intakes are the LD4B and PERFORMER intakes. I am leaning towards the PERFORMER as I can buy it new online. If someone could provide pros and cons to these as well as ease of swapping either onto my stock 273 1967 v8. As well as what carb may be best for my goal/setup.

The second upgrade I was considering doing alongside this was my exhaust and/or headers. I really hate how quiet the car is lmao. I do have a muffler that i bought months ago before I was in an accident with my car. While my car is currently being repaired in the shop i want to do my research and prepare/buy parts to upgrade the dart once I get it back. I will attach a photo of the muffler I bought below. I believe I can only use this muffler if I keep the car single exhaust (IF someone can confirm this that would be great).

However, I am thinking of going to dual exhaust and want to know the best/most affordable way to do that with regards to headers, X pipes, H pipes, etc. Any info on this would be greatly appreciated. How much of a sound/performance difference will dual exhaust make?

I browse SUMMIT booklets etc and look at headers etc and was curious for example when I see headers that say they're applicable to a 273 mopar. How many issues would I have fitting them etc? More insight/advice on headers would be nice as well as if I need them to do dual exhaust.

Appreciate any info/advice as well as tips on other upgrades you guys think I should maybe focus on. SORRY for the noob questions thanks guys.

Muffler.jpg
 
Just my 2 cents...

If you stick with stock parts you will be much happier. Easier to assemble and maintain.

The power increase between 2bbl and 4bbl and dual exhaust will be minimal.

The factory 2bbl was 180 HP, the 4 BBL was 235 but that was due to the cam and 10.5 compression. The heads, valves, exhaust manifolds, etc were all the same.

The exhaust system was single but with slightly larger tube.
 
Rear Gears, stall and shift kit, plus a good tune recurving the distributor are possible mods along with your 4bbl and headers upgrade.
 
if you don't already have electronic ignition with a properly curved distributor that should be number one on your list with a bullet.

cheap, easy and compliments every modification you'll undertake down the line.

after that, a cheap dual plane manifold-- you can pick up a performer new or used that will work great. obviously, stock 4bbl manifolds are out there as well and while they're heavy they do the job damn well. obviously there's other aftermarket brands out there such as weiand and offy, but the performer (or a stocker) is going to be the best match for your motor.

small 4bbl carb-- 600~650cfm is what you're looking for. a used carter afb/edelbrock are in abundance and have tons of tuning parts and are dead simple to dial in. a carter avs2 would be an excellent choice as well. if you're willing to learn and put the time in, you can reap rewards with a spread bore carb such as a thermoquad or q-jet, but know going into it that the learning curve is steep.

on exhaust, a true dual system is great for uncorking the power. but exhaust is one of those things where you can pay a little bit of money for something that works, or a lot of money for something that works really well. cheap headers hang low, bang all over everything and are a pain to install and rust out. expensive headers tuck up tight, have clearance, install easier and tend to last longer. and while headers will pick up power everywhere, this being a lower performance street car you're not going to see massive gains for the money spent, so it's kind of a personal choice on headers vs. keeping the stock manifolds and just running duals.

i understand budget and skill dictates a lot of upgrades and modifications. but you should be able to do the most basic of hot rodding upgrades on a beer budget with basic hand tools and greenhorn mechanical skills.

keep in mind, changing to a 4bbl means modifying your transmission kickdown linkage as well as your throttle cable/linkage-- this topic has been covered extensively here, so use the search function.

also, there's nothing wrong with keeping your 273 2bbl. get it set up with electronic ignition and a nice curve, throw a tune up at it, get everything dialed in, pop for dual exhaust and see how you like it. you may just be surprised!
 
I agee with above. I would use the four barrel manifolds and go dual exhaust. As nice as headers are they are costly and can be a PITA . Maybe there's some shorty headers? I have no experience with them. Good luck.
 
You could spend a bunch of money and time buying various parts OR you could just have your heads ported and get more HP. Just find a set of 308s and clean up the bowels / valve job / backcut the intake valves . .
If the engine is original it’s probably close to needing one anyway . And you would have a solid base to build from which will complement any future upgrade . Then that 4 barrel intake will make a difference.
 
Call Brian @ IMM down there in Cali . I think he goes by @ou812 . At least on Speedtalk he does .
 
mbaird said:
You could spend a bunch of money and time buying various parts OR you could just have your heads ported and get more HP. Just find a set of 308s and clean up the bowels / valve job / backcut the intake valves . .
If the engine is original it’s probably close to needing one anyway . And you would have a solid base to build from which will complement any future upgrade . Then that 4 barrel intake will make a difference.
Click to expand...
Why 308's ? Why ported ? Most would think that 360 heads are over kill nevermind ported on a stock cam, cr, 273.
 
in order i'd go dual exhaust, 4 barrel inlet and carb, electronic ignition then headers. if you installed a little more cam while the inlet was off then so much the better. have fun :thumbsup:
neil.
 
rims tires
carb
intake
electronic ign
manifold back exhaust
shift kit
nitrous
 
Ignition first, hands down. Just don't get suckered into one of those all-in-one cheapo internet distributors- more problems than they're worth. Get the actual Mopar wiring conversion kit, a good ignition box (avoid the "orange boxes", lots of issues in recent years. In your situation I'd get something like the Standard LX101, solid and reliable), and a distributor with a nice advance curve built into it from @halifaxhops.
From there, follow up with good wires, a quality cap and rotor, and plugs of course.
And don't forget to set your valve lash- who knows how long it's been and could be a good ways off.
Then attack your wiring (you did say reliability was important). Clean all your connections at the bulkhead connector, at the components themselves, and get all your grounds squeaky clean and tight. You'll thank me later- any performance upgrades you do in the future will only work if the engine starts and runs consistently...
Then upgrade your alternator and voltage regulator to the later electronic type. Do a search in the electricals forum to get the lowdown on how it's done.
Then duals from your exhaust manifolds. The HP single is awesome, but pricey- you can get duals done much cheaper.
As far as intake/carburetion goes, initially I'd just rebuild the 2 bbl. As previously stated, a 4 bbl. swap entails other details like the throttle and kickdown linkages, and adapters for the throttle lever, etc. A good running 2 bbl. will give you good street manners and still be adequately peppy until you source all your 4 bbl. pieces. And as you source those pieces, don't forget some used out of production pieces like the Eddy Streetmaster 318, SP2P, or Holley Street Dominator- all of which work quite well on the little 273 and are generally more affordable due to their lack of desirability for bigger engine builds. As for a carb, a 500 Eddy would be about right; although anything up to 600/625 will work just fine- pick your poison, Holley or Edelbrock/Carter.
 
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Can't believe so many are against going 4bbl, who the hell wants a performance engine with a two bbl, it's basically free on tap power, it's two bbl 99% of the time and 4bbl when needed no real down side if chosen and setup right.

Like people said performer or similar intake, even stock 340/360 and a 600 ish carb, I wouldn't use the stock 273 intake doesn't look like much of a performance piece to me.
 
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273 said:
Can't believe so many are against going 4bbl, who the hell wants a performance engine with a two bbl, it's basically free on tap power, it's two bbl 99% of the time and 4bbl when needed no real down side if chosen and setup right.

Like people said performer or similar intake, even stock 340/360 and a 600 ish carb, I wouldn't use the stock 273 intake doesn't look like much of a performance piece to me.
Click to expand...
Redhelmet said:
I want to make the car more lively and powerful without going too far obviously as mileage and reliability are important.
Click to expand...
Nobody's saying they're against a 4 bbl., just that it isn't the priority until he gets his other ducks in a row. And yes, a 2 bbl. can perform, just look at Sportsman short trackers all across the country.
Ignition first. Then exhaust. It's no benefit to get more air in if you can't get it out.
 
Professor Fate said:
Nobody's saying they're against a 4 bbl., just that it isn't the priority until he gets his other ducks in a row. And yes, a 2 bbl. can perform, just look at Sportsman short trackers all across the country.
Ignition first. Then exhaust. It's no benefit to get more air in if you can't get it out.
Click to expand...
They don't perform they function and are only used because of rules, those engines would pick up a lot of hp if swapped to a 4 bbl. Could he stay stock 2bbl sure but if looking for more power it one of the most basic upgrades there is.
 
And who doesn't like the sound of kicking in the back barrels :)
 
273 said:
Makes more sense, but doesn't the OP' 67 273 already have closed chamber heads, and 273 are pretty decent flowing heads especially on 273 cid.
Click to expand...
Yep, these heads with 1.94/1.88 in and 1.6 exh valves along with bowl blending and a gasket match will increase performance along with a recurved mopar performance electronic ignition setup. It’s performance that doesn’t wear out.

After that I would look into the 4 barrel setup and a quality header exhaust system.
 
Professor Fate said:
Ignition first, hands down. Just don't get suckered into one of those all-in-one cheapo internet distributors- more problems than they're worth. Get the actual Mopar wiring conversion kit, a good ignition box (avoid the "orange boxes", lots of issues in recent years. In your situation I'd get something like the Standard LX101, solid and reliable), and a distributor with a nice advance curve built into it from @halifaxhops.
From there, follow up with good wires, a quality cap and rotor, and plugs of course.
And don't forget to set your valve lash- who knows how long it's been and could be a good ways off.
Then attack your wiring (you did say reliability was important). Clean all your connections at the bulkhead connector, at the components themselves, and get all your grounds squeaky clean and tight. You'll thank me later- any performance upgrades you do in the future will only work if the engine starts and runs consistently...
Then upgrade your alternator and voltage regulator to the later electronic type. Do a search in the electricals forum to get the lowdown on how it's done.
Then duals from your exhaust manifolds. The HP single is awesome, but pricey- you can get duals done much cheaper.
As far as intake/carburetion goes, initially I'd just rebuild the 2 bbl. As previously stated, a 4 bbl. swap entails other details like the throttle and kickdown linkages, and adapters for the throttle lever, etc. A good running 2 bbl. will give you good street manners and still be adequately peppy until you source all your 4 bbl. pieces. And as you source those pieces, don't forget some used out of production pieces like the Eddy Streetmaster 318, SP2P, or Holley Street Dominator- all of which work quite well on the little 273 and are generally more affordable due to their lack of desirability for bigger engine builds. As for a carb, a 500 Eddy would be about right; although anything up to 600/625 will work just fine- pick your poison, Holley or Edelbrock/Carter.
Click to expand...
TY so much for the detailed reply. I have another stupid question. I can do duals from my stock exhaust manifolds? I do not need to change anything or get headers to do that? Once I buy headers down the line would it just be as simple as bolting them to the rest? Also the muffler I attached would I need to buy two different mufflers or could that one still work if I do dual setup?
 
yeah you can do duals off your stock manifolds. then down the line when you install headers you just hack the system back and connect it in.

you'll need two mufflers, so either another one of those if it's what you want and it fits or two mas.
 
junkyardhero said:
yeah you can do duals off your stock manifolds. then down the line when you install headers you just hack the system back and connect it in.

you'll need two mufflers, so either another one of those if it's what you want and it fits or two mas.
Click to expand...
Thank you! I am super excited to make the car way louder. One of the workers at the shop started my car and actually told me he could barely tell it started because of how quiet it was....

After reading through the replies I will most likely wait on headers. Will dual pipes and two new mufflers make a world of a difference in volume without the headers? If anyone has any recommendations on headers for my application just for me to reference and see prices that would still be appreciated as well.

THank you all for the replies!
 
yeah man, it'll make it louder. volume is kind of a product of pipe length, muffler, and compression. if you have full exhaust to the bumper it'll be quieter than dumping it at the axle after mufflers.

but you're running a relatively low compression stock motor, unless it's straight pipes out the side it's not gonna sound full race car.

headers: TTI or dougs. some people have had success with the cheap summit headers, but you really get what you pay for in this department.
 
First things first. Tune the 273 up. Start by adjusting the valves, they should be solids. Make sure the passenger side exhaust flapper valve is working or at least open. Set the timing to 10 degrees BTDC. I'd rebuild the 2 barrel carb to keep you running till you get all the parts to make that 273 a performance engine. Your heads are good as is your compression, almost 9:1. Are you running an automatic transmission? I have to agree on starting with a quick curve distributor, and would suggest @halifaxhops. The 4 barrel swap is more involved and a number of changes have to be made at the same time. Do you know what has done to your engine?

The best thing you can do for exhaust is use the 67 Barracuda Commando exhaust. It uses your factory exhaust manifolds, the y pipe empties into a 2.50 OD pipe and runs to a muffler with a 2 1/4 tail pipe. The 2 1/4 tailpipe uses the standard HP pipe hanger. It will work very well no matter what mods you make in the future. The complete system is about $550 from Waldron's Exhaust and is a copy of the original 4 barrel system minus the resonator.

waldronexhaust.com

1965-67 Plymouth Barracuda V8 273ci 4 BBL Carburetor Single Exhaust w/Resonator Eliminator Pipe

SKU: 438533
waldronexhaust.com waldronexhaust.com

The earlier system was straight thru muffler and resonator included. In the mean time you could run a straight thru glass pack like a Cherry Bomb on the 2 barrel exhaust system.

cherrybomb.com

Cherry Bomb® Glasspack - Cherry Bomb® - Disturbing The Peace, Since 1968

Cherry Bomb® Glasspack The original high performance Cherry Bomb® with its straight-through design maximizes horsepower and offers those classic rumble and bark sounds for cars and trucks. FEATURES & BENEFITS:• Straight-Thru Design• 100% Welded Construction• Classic Cherry Bomb® Red Paint•...
cherrybomb.com cherrybomb.com
 
66fs said:
First things first. Tune the 273 up. Start by adjusting the valves, they should be solids. Make sure the passenger side exhaust flapper valve is working or at least open. Set the timing to 10 degrees BTDC. I'd rebuild the 2 barrel carb to keep you running till you get all the parts to make that 273 a performance engine. Your heads are good as is your compression, almost 9:1. Are you running an automatic transmission? I have to agree on starting with a quick curve distributor, and would suggest @halifaxhops. The 4 barrel swap is more involved and a number of changes have to be made at the same time. Do you know what has done to your engine?

The best thing you can do for exhaust is use the 67 Barracuda Commando exhaust. It uses your factory exhaust manifolds, the y pipe empties into a 2.50 OD pipe and runs to a muffler with a 2 1/4 tail pipe. The 2 1/4 tailpipe uses the standard HP pipe hanger. It will work very well no matter what mods you make in the future. The complete system is about $550 from Waldron's Exhaust and is a copy of the original 4 barrel system minus the resonator.

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The earlier system was straight thru muffler and resonator included. In the mean time you could run a straight thru glass pack like a Cherry Bomb on the 2 barrel exhaust system.

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Click to expand...
Thank you for the reply and yup it is an automatic! I know the original owner said the engine was "rebuilt" but I never talked to him for specifics. I am definitely going to check out/purchase one of those distributors and probably try to do dual exhaust with the muffler i have if possible.

I'm leaning towards doing headers at the same time so i don't have to go back and add them in later. So id like to hear opinions on TTI vs DOUGS and if theres any specific products from them that would be best/easiest to install! (LINKS would be appreciated).

Also I saw on the forums that dumping the exhaust before the bumper is cheaper and sometimes easier on the 67 darts (Correct me pls if im wrong) But what is your guys' opinion/advice on dumping the exhaust early as opposed to taking it all the way to the bumper, pros and cons of each?
 
Also curious if once i have headers and mufflers ready if my local shop can do the rest or do i need to buy/supply any more pipes etc
 
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