1972 340 w/400-450 HP what is a good carb setup.

My 340 was completly rebuilt using good quality parts. My engine builder says is will be producing 400 to 450 HP. Ive been bouncing different carb setups and wanted to ask what would be a excellent setup to run on a car that will be drivin on the street daily during the warm months. Im not a engine expert by any means so im here to find out what you guys think i want it to be a well balanced running engine i know too much carb or too little can choke performance what do you Moparts members think would be good. I have a OE Holley 70 340 4-spd six pack setup and OE intake manifold off a 70 TA Challenger would that be enough CFM for my engine ?.

My 340 was in the 450 hp range and it ran good with a 750 dp.

Thanks thats good to know. What make of carb was it ?.

I have an AAR with the factory six pack. I’m a good tuner and it runs good and looks good. The best running 340 car I ever drove was a TA four speed with 700 DP Holley. But if I had my choices, nowadays you run fuel injection.

A 1972 Thermoquad would be perfect for your set up. My engine builder was amazed at how well it worked on my engine. Talk to Scott Smith at Harms Automotive- http://www.harmsauto.com/

i AGREE.
look into some of the self learning throttle body stuff.
by the time you buy everything for the car fuel injection won't be that much more than a carb setup. and it will run, start and respond much better than a carb and you won't have to rejet and tune all of the time. a large factory air cleaner can hide everything and no one will know you are fuel injected unless you tell them.

The double pumper carbs are good carbs and would be a good recommendation if the car would spend it's time at the track. Because it is a track oriented carb. But that makes it way too rich in the transitions for the typical street applications.

All carb manufacturers make carbs that are track oriented and carbs that are street oriented. They do that because there is a difference in when and how much fuel needs to be delivered between the street and the track.

Here are a couple of articles regarding the Street Demon carb. And there are plenty of others out there if you want to do a search. I have installed Street Demons on several different cars and believe that they are the best carbs for mild street cars whose owners want a plug and play carb with good street manners.

http://www.carsillustrated.com/tech-got-me-one-of-those-double-pumpers-street-demon-carburetor/

https://www.youtube.com/watch?v=jN2xbt6Mzdc

https://www.youtube.com/watch?v=DPOuEOkazVc

That is simply NOT true!

New Street Demons and throttle brackets are all over Ebag, Amazon, etc for $350-$400, all in. I usually buy refurbished, which are even less.

Show us the complete EFI systems that aren't that much more. And the customer reviews that go with them. You also forgot to mention the much more involved installation process for EFI and it's learning curve.

I'm obviously a carb guy and will agree that in many ways fuel injection is a more efficient system. However, with a vintage car those selling/promoting fuel injection are (in general) exaggerating the simplicity and cost associated with buying and installing them.

Carb choices? as mentioned, a 750cfm carb would be a good choice for your estimated power level. Holley, Demon, or stock, performance will be similar within a few HP. Personally I think a 72 TQ would be a great choice, I've done dozens of them for past customers with similar engines and have never heard anything negative. If stock isnt your bag I'd go with one of the new Street Demon carbs (they look a lot like a TQ). Great new design and simple to tune.

.02

Best street manners I've ever experienced in that power range was a Thermoquad properly done. Crisp response, good MPG, lacked nothing for power in that application/power level.
It's easy to be seduced by big CFM, but most of the time a street engine's at low RPM or in transition. The small-primary/large secondary T-Quad is really good at that when done right.

i'm a T-Quad guy myself. it took me a looong time to figure them out back in the day when they were new [way before the interwebs], but when i finally figured them out, they proved to be the best of both worlds. good street manors, and worked well at the track to boot ! just my opinion, your mileage may vary.

Really depends on you mostly. If you don't own a carb and don't know a lot about carbs then get a simple street carb like a 600 cfm Edelbrock.

Personally I'd put a Holley Sniper on there but it is about a $1500 investment by the time you consider the new fuel tank and internal pump. In the long run you'll enjoy the Sniper and you'll wonder why you ever considered a carb but you have to get over the learning curve.

I was amazed on how my stroker performed with a T quad.

I run a Demon 850 cfm in my Duster, but my horsepower level is higher
than your application. That said, I would use a Thermoquad, on your 340.
Get a hold of Scott, as others have mentioned, he can set you up with a nicely restored Thermoquad that will perform well.
BTW...what combo did you use in your 340 build? IE: cam/compression/pistons/intake/headers/manifolds,etc?? Just curious!

What cam is in it?

At 400 to 450 hp with a 340 I’m thinking it’s fairly aggressive. Probably not a lot of vacuum. But would have to see cam specs.

I’m thinking you might need something with adjustable throttle blades and four corner idling is just a street hippo stall converter

One thing never mentioned is the howl a TQ makes when all four butterflies open up.

It'll turn heads

From the inside

https://www.youtube.com/watch?v=NeVPX3MMGGs

I just talked to Scott at Harm's i have a OE 70 TA Challenger 4-spd six pack setup and OE intake manifold im going to use. Im shipping Scott my carbs for a OE restoration. He said they will work great for a daily fair weather driver as i want to drive it alot good guy to talk to he knows his craft well and i dont mind paying big $$$$ for restored carbs from Harm's. Thanks to all that chimed in i love this site and the members on it Mopar guys really do help each other out .

Back in the 70's I had a '69 340 swinger that ran 12.8's with a Holley 800 spread bore DP, factory iron intake with spread bore adapter, 3,500 B&M convertor, headers, JC Whitney 500 lift/ 300 duration cam and 5.13 gears. The pic is the Swinger at Hawaii Raceway park (now closed).

maybe a little more. i would figure about $1K for a COMPLETE FITECH system with external walbro fuel pump and lines.
from what i have read they are pretty good overall system with a not so complicated setup.
once installed with the basic parameters programed in. then a couple trips around the block it's ready to go. it's self learning so the more you drive it the better it runs.

now with a carb the initial buy in is just part of the price. the weather changes you have to re jet and adjust, the weather changes you have to adjust again. with the alcohol mixed fuel it will eat the seals, accelerator pumps, and floats. now you gets leaks. really hot day you get vapor lock. sit for a while when hot and the fuel boils in the carb. sit for weeks at a time you have no fuel in the car and have to crank and crank until it starts.
i know i am exaggerating a bit on the problems, but they do happen a lot. jets, gaskets, air bleeds all cost $$. it adds up. when i had my hemi with a carb i was adjusting it almost every other day. the temp changes 15* and adjust again. runs great in the morning runs a little rough in mid day runs like crap in the evening. or maybe runs great in the AM and PM runs like crap in the daytime.
self learning FI almost none of the listed problems happen. hop in and drive. even when it's running a bit off, it is probably running better than a carb could hope to.
i know it's not a FITECH system. but my 08 supercharged mustang the only thing i have to do is fill it up and drive. change the plugs 1 time a year and change the oil every 2K miles. car makes 650rwhp on pump 93, runs 10's all day long at the track if i don't miss a shift, drive it to the track, drive it home and gets 25mpg. never had ANY of the above listed carb problems.
the only thing i do to it is load my race tune at the track, 5* timing and richen it up a little bit with my hand held tuner don't even have to open the hood to do it.

From what I read

Famous last words.

You try running an EFI setup with just an external pump and a stock tank you will suck air regularly.

Your carb "issues" are grotesquely overblown as well.

Hyperbole, look it up

Well.....your estimate for the cheapest EFI system is still over twice the price of the carb set-up. And will probably pass triple the price for many users. And that is still the cheapest set-up with an external pump, no costs for sumping the tank, assuming the installer can handle all the connections, etc. And that cheapest kit is not necessarily the preferred set-up.

What about ignition control? Seems important to get the most from an EFI system. Any extra costs or labor to that?

You seem to have more carb problems than the rest of the posters here. Personally, I do not experience the issues you list with my carbs.

If you want to believe that the cheapest EFI system that is 2 or 3 times the cost of the preferred carb is the way to go.....then go for it. But at least be honest about the comparison and compare apples to apples.

Back in the day a 3310 Vac sec Holley was the go-to carbs on thousands of builds. Funny that you don't hear more about them any more. But I'd put that carb on anything from a 340 to a 440 and not worry about over carbing it or it running too fat. Great carb to learn tuning on; swapping jets in the primaries, springs in the secondary diaphragm and plates or jets in the secondaries.

I have $1800 into my Fitech conversion, all the little extras do add up.
I went with a new Spectra tank with in-tank fuel pump, so that was $260 just for the new EFI tank. Start adding in the extra fuel & return lines, modding exhaust for O2 sensor, etc.................

But, the car is so much more enjoyable to drive.
The biggest benefit is the greatly reduced stinky gas smell is almost zero.
My daughter didn't want to go for rides when car was carbed, "my clothes smell like gas and I have to take a shower"

The closed system lowering the smell and no more hot starts issues have sold me on EFI. Would never consider a carb again.

That sixpack you got will have more than enough CFM for your powerlevel,the intake might not be perfect for this but if you already have it just run it,it might take some time getting the tune just right but its a damn cool intake/carb combo

I have a 750 AED on my 450hp 340....it’s one of the reasons it’s making 450 plus...

Bull $hit. I read that if frogs had wings they wouldn't bruise their arses when they landed.

Good old 750 Holley double pump worked well for me.

Id say 750 dp, but my next project i would like to try a Fitech.