Carb recommendations for my 340

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RB340SBM

RB340SBM

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Hey everyone,

Looking for a carb recommendation for my 340. Car is a 71 Dart swinger with a 727 that has a shift kit and an old hurst autostick 1. Engine is 10:1 with a 484 purple cam, ported x heads, TTI headers and can’t exactly decide on intake. Currently has an LD340 mounted right now but plenum divider is removed from previous owner and not sure how well the car will be in terms of street manners as it’ll be a street car with occasional trips to the track a few times a year. Worst case I have an air gap on the side. What would you guys recommend? I’m new to carbs so would like to find something that’s good but simple enough for me to learn to tune.
 
RB340SBM said:
Hey everyone,

Looking for a carb recommendation for my 340. Car is a 71 Dart swinger with a 727 that has a shift kit and an old hurst autostick 1. Engine is 10:1 with a 484 purple cam, ported x heads, TTI headers and can’t exactly decide on intake. Currently has an LD340 mounted right now but plenum divider is removed from previous owner and not sure how well the car will be in terms of street manners as it’ll be a street car with occasional trips to the track a few times a year. Worst case I have an air gap on the side. What would you guys recommend? I’m new to carbs so would like to find something that’s good but simple enough for me to learn to tune.
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Intake is an excellent piece.

770 Holly Street Avenger with vacuum secondary's for street use with an electric choke.

Holley 0-80770 770 CFM Street Avenger Carburetor

Works fabulous on my 408 stroker.
 
Many carbs can be made to work well; but personally, with your relatively mild build and intended use I'd stick with the LD340 and top it off with an AVS II 650. Good tuneability and great street manners. No matter which carb you ultimately use, make sure you also get the correct linkage adapter so the throttle and kickdown linkages function as intended.
 
Quick Fuel Brawler 750 DP. Nothing else is as tuneable in its price range. NOTHING.
 
On the street;
As for size, any 4bbl from 580 to 800 will be fine. the smaller ones are more responsive under 60mph, with street gears.
As for easy to work on, it's hard to beat a Holley.
As for the hiway, a small spreadbore is the way to go, and with metering rods is even better.
Over all, the Thermoquad is , IMO, incredibly versatile. Personally, I love how the TQ roars with an automatic, and unsilenced air cleaner. You can hear them working from a long way off. And from the front seat, it's magic.
 
AJ/FormS said:
On the street;
As for size, any 4bbl from 580 to 800 will be fine. the smaller ones are more responsive under 60mph, with street gears.
As for easy to work on, it's hard to beat a Holley.
As for the hiway, a small spreadbore is the way to go, and with metering rods is even better.
Over all, the Thermoquad is , IMO, incredibly versatile. Personally, I love how the TQ roars with an automatic, and unsilenced air cleaner. You can hear them working from a long way off. And from the front seat, it's magic.
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The only spreadbore that I could find was a holley 650. Is there others out there?
 
As others said, 750 cfm.

Brand ? I like holley and quickfuel
I don't like the avengers because they are calibrated lean. The 670 for instance, a 650 classic dp would be better...
You need the 770 to compensate for lack of a 700 or 750 dp..and even then..
 
junkyardhero said:
Q-jet, baby
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Oh boy, I hope that I don't open up a can of worms here, but I've never seen a Q- jet on a mopar. Not saying that it hasn't been done or won't work. Does the Q- jet require some type of special linkage for the throttle and for the transmission. What intake manifold will accept the q jet or does it require a adapter? I known a guy who used to be good at tunning a Q jet because he couldn't afford a holley. Again I'm just asking
 
QJ is a spreadbore like the TQ. Same bolt pattern. You need to check fitment to the intake to make sure all the passages in the carb base are covered & that linkages do not foul etc....
 
Dan the man said:
Oh boy, I hope that I don't open up a can of worms here, but I've never seen a Q- jet on a mopar. Not saying that it hasn't been done or won't work. Does the Q- jet require some type of special linkage for the throttle and for the transmission. What intake manifold will accept the q jet or does it require a adapter? I known a guy who used to be good at tunning a Q jet because he couldn't afford a holley. Again I'm just asking
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somewhere i think in the 80's there some mopars came with q-jets
 
I am running a 750 Edlebrock on my 71 340 with a 509 purple cam with 3500 stall with a Trans go shift kit. My 340 loves the 750 Eddy..
 
Dan the man said:
Oh boy, I hope that I don't open up a can of worms here, but I've never seen a Q- jet on a mopar. Not saying that it hasn't been done or won't work. Does the Q- jet require some type of special linkage for the throttle and for the transmission. What intake manifold will accept the q jet or does it require a adapter? I known a guy who used to be good at tunning a Q jet because he couldn't afford a holley. Again I'm just asking
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I'm not sure if a QJ ever came on a car engine but they did come on trucks. IIRC it was after Carter got bought out for the umpteenth time that Chrysler changed to the QJ.
 
Newbomb Turk said:
I'm not sure if a QJ ever came on a car engine but they did come on trucks. IIRC it was after Carter got bought out for the umpteenth time that Chrysler changed to the QJ.
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They did. They came on some cop cars. Dippys and such.
 
RB340SBM said:
Hey everyone,

Looking for a carb recommendation for my 340. Car is a 71 Dart swinger with a 727 that has a shift kit and an old hurst autostick 1. Engine is 10:1 with a 484 purple cam, ported x heads, TTI headers and can’t exactly decide on intake. Currently has an LD340 mounted right now but plenum divider is removed from previous owner and not sure how well the car will be in terms of street manners as it’ll be a street car with occasional trips to the track a few times a year. Worst case I have an air gap on the side. What would you guys recommend? I’m new to carbs so would like to find something that’s good but simple enough for me to learn to tune.
Click to expand...

Oh man you opened up a can of worms! LMAO.

AJ is right on carb size working from little to big. Considering the build, I’ll also assume a decent gear ratio is back there for the go fast effect.

I can only say what I would do and having used a 600 AFB to a 750, I liked the 750 a little better. Even on the lower rpm side of just around town or initial take off, there was a better and more powerful feel from the gas pedal. Of course, everything will be the state of tune.

If you don’t have a preference of intakes, I would use the RPM. I’ve had both intakes, so there’s that behind my choice. Nether is bad and nether is worth getting rid of for the other. Since you have both, try it for yourself and decide.

Some will run the LD-340 because it’s a ”Day 2” hot rod part and others will run the rpm without care or concern of that period correct hot rod part.

So far my favorite combo was the MP tips modified LD-340 and the big TQ.
 
As for QJ versus TQ, on a 340, on the street;
Mechanically, I have mixed feelings as to which I prefer.
As to appearance, my opinion is that the TQ is way more handsome, and hands down way more intimidating to look at .
As to drivability and throttle response around town, I think it's really hard to beat a spreadbore, any spreadbore. as the Compression ratio drops, the more you're gonna agree.
As to fuel economy I'm leaning towards the QJ. They have a hard-to-beat booster set-up.
As to absolute power, size for size, it's probably a toss-up.
>However, Carters are rated differently than Holleys, and IDK about QJs, so it's very possible that a like-rated carb from each of the three, is not gonna make the same absolute power. This is why you can put a big-primary TQ on a 318, and it works about exactly like a like-sized 2bbl, until the secondaries start to come in; adjust it right, and if it didn't moan, you'd hardly know it was a 4-bbl.
 
Newbomb Turk said:
I'm not sure if a QJ ever came on a car engine but they did come on trucks. IIRC it was after Carter got bought out for the umpteenth time that Chrysler changed to the QJ.
Click to expand...
First off let me say that it's highly possible that I may not have looked in the right place but I didn't find any information on a q jet being used or available for a sbm
 
Dan the man said:
Oh boy, I hope that I don't open up a can of worms here, but I've never seen a Q- jet on a mopar. Not saying that it hasn't been done or won't work. Does the Q- jet require some type of special linkage for the throttle and for the transmission. What intake manifold will accept the q jet or does it require a adapter? I known a guy who used to be good at tunning a Q jet because he couldn't afford a holley. Again I'm just asking
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I remember seeing those QJs on Mopars, IIRC in the late 70s.
As to special linkages, no, just the typical KD stud.
I'm notta fan of sticking a TQ on a square bore intake, with an adapter. Thankfully Mopar has a nice cast-iron spreadbore intake, but it is a big-port; and I'm notta fan of installing those on small-port 318 heads. Yes I know, it's been done, but all you gotta do is swap it out for a small-port intake and make a note of the difference in drivability at low to mid throttle settings, and specifically in the throttle response. In 50 plus years, I've done it about every which way you can, and for myself, I'll never run a big-port intake on a small-port head again.
Of course, I'll never run a 273 again either, so long as 360 cores are plentiful, lol. Think of a 360 as the ultimate bored and stroked 273, lol Set one up right, and it will do everything a 273/318 can do with near double the power and/or torque.
Well getting 30 mpgs out of either one does take a little more ingenuity with the 360.
Some say the 273 revs faster,
Well I tell you what, car for car, put your 273 in gear, and pull up beside me, and let's go!. I'll even give you a headstart, and ask me how much I don't care that your 273 might neutral-rev faster than my 367. I say might, cuz you're gonna need an electronic timer to measure the difference. And while you're 273 is busting a nut trying to keep up, my 367 is gonna be cheering you on from the return road.
lol
Back on topic,
I'm pretty sure I've seen an aftermarket, small-port, spread-bore intake, back in the day.

As to your previous question as to spreadbores, IIRC, the AVS's were also spreadbores, just not as exaggerated as the TQ.
 
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