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.
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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.
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Redhelmet said:
I want to make the car more lively and powerful without going too far obviously as mileage and reliability are important.
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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.
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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 :)
 
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