Why run dual quads?

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halfafish

halfafish

Damn those rabbits, and their holes!
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I was doing a little thinking-over-coffee this morning, and while perusing some threads where dual quads were a topic I came up with more questions than answers. In a nutshell, why would a person want to run dual quads instead of a single carb? For sure there is the coolness factor and visual appeal but otherwise what's the benefit? If running a pair of 600 CFM (or whatever size) carbs why not just run a big single 4-barrel?

Enquiring minds want to know...:)
 
I've always wondered it too especially on a small block
 
halfafish said:
I was doing a little thinking-over-coffee this morning, and while perusing some threads where dual quads were a topic I came up with more questions than answers. In a nutshell, why would a person want to run dual quads instead of a single carb? For sure there is the coolness factor and visual appeal but otherwise what's the benefit? If running a pair of 600 CFM (or whatever size) carbs why not just run a big single 4-barrel?

Enquiring minds want to know...:)
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As far asI know the reason now days is just because cool.
But when multiple carbs became the hot ticket for performance in the 40's,50's and 60's you couldn't easily get a 1200 cm carb.
 
Partially depends on the style of intake being used. In my case, I chose to run a tunnel ram, which gave a large performance boost over the single plane. Dyno tests have shown less than desirable results from running single carbs on tunnel rams, so dual carbs it is.

Due to the season, I did not get carbs absolutely dialed in to optimum performance. I can say with certainty, driveability, manners, and performance were all equal to, or improved over single setup. Mileage went from 17.4MPG imperial to 15.6, not nearly as bad as I expected. Again not fully dialed in. Drove it on an 800 mile trip with no issues.

Many people claim tunnel rams, or dual quads are not street friendly. I would suspect these are the same people who haven't done it. Oh, and I have no chokes either.
 
The only thing that comes to mind is better fuel distribution at wide open throttle, and of course the engine underneath must be able to handle all that fuel. I ran 2 Edelbrock 1406's on a 472 Hemi, richened up the jets in the rear carb and it ran super. But looking for the ultimate tried Fi Tech with 2 throttle barrels and now have Edelbrock pro flow4 and haven't completely dialed it in yet and runs pretty good.
 
To quote: "coolness factor and visual appeal". That's it. Period.


Bottom line: 70 years ago there were NO big four barrels. If you needed more airflow you put on more carbs. It was necessary then. Now? Not so much


Unless of course, if you have a LOT of motor that needs a couple dominators on a tunnel ram.


Edit: to me, "dual quads" means a low rise two four barrel setup to be under a stock hood. A tunnel ram with dual quad top is a different animal. And even a tunnel ram can be primarily used for eyewash too, if the engine doesn't need it.
 
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halfafish said:
I was doing a little thinking-over-coffee this morning, and while perusing some threads where dual quads were a topic I came up with more questions than answers. In a nutshell, why would a person want to run dual quads instead of a single carb? For sure there is the coolness factor and visual appeal but otherwise what's the benefit? If running a pair of 600 CFM (or whatever size) carbs why not just run a big single 4-barrel?

Enquiring minds want to know...:)
Click to expand...
A single 4bbl is easiest no doubt. For me, it’s the look. The throttle response can be a little more aggressive in feel since you have more carb opening up vs a single carb.

A dual plane vs a tunnel ram is twisted different universes.
Both can be streetable or raced.
MidnightSwinger said:
For me, it’s the look. Having multiple carbs can be a headache, but nothing looks cooler.
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I don’t see how. Even more so with a pair of Cater style carbs.
Jet it, set it, forget it, you’re done.
tonysrt said:
The only thing that comes to mind is better fuel distribution at wide open throttle, and of course the engine underneath must be able to handle all that fuel. I ran 2 Edelbrock 1406's on a 472 Hemi, richened up the jets in the rear carb and it ran super. But looking for the ultimate tried Fi Tech with 2 throttle barrels and now have Edelbrock pro flow4 and haven't completely dialed it in yet and runs pretty good.
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318 will run did a pair of 600 Edelbrock carbs on his otherwise stock 318. Check out his video.

Better fuel distribution is possible. That will depend on the intake and how well balanced it is. I’d bet no matter the intake, some die grinder work would help any dual quad intake out.

When you say the engine underneath has to handle all of that fuel, you make me laugh like an old saying… all the carb and you’ll drown the engine out, maybe even blow it up. This is ridiculous and I’m surprised you even went there since no matter what carb or carbs you use, you tune it for the engine.

So once you rejet the carb(s) for the proper amount of fuel to be consumed, ….. do I need to continue this????
 
Because tunnel ram. enuf said. It was a seat of the pants (no dyno numbers) huge difference in torque and response going from a Torker/750vs, then 850dp and now a pair of 660 center squirters on the tunnel ram. Driven 500 mile commute to MITP and 11mpg. Whether 10° or 100°+, it just works. That's no chokes and 1:1 linkage....yes all 8 barrels open together all the time. Nothing like it when running NA.
 
Those that have t done it don’t get it.

Therefore, explains it probably won’t cut it. You understand it when you have been there and done that.

Many wonder why most don’t go back to a single 4bbl. carb. That should really tell you all you need to know.

The other funny thing is almost all say, “Biy I but that sucks down some gas!” Of course it does I say.

Then you get **** for mileage is the retort. That’s largely governess by the weight of your right foot and the build under it.

As Stone Cold Steve Austin says!
“And that’s the bottom line!”
 
The dual quads on my 318 were hooked 1 to 1. The car starts, idles and runs unbelievably well whether cruising around town, going down a highway, or smashing it to the floor. I don't know what the exact gas mileage difference was because I didn't check, but by the gage really no big difference that I could see.
However, they are being removed because of a specific project with the car, no other reason.
 
Thanks Troy, my experience is very limited and in all reality I had intend to use the Offy lowrise #5488 DQ on my 340 build for cool factor and for power. Most material I've read states very little difference in power from DQ to single 4bl. I discovered the port size was a huge mismatch for the 340. That DQ was designed for 273/318. So I put it on the 273 and made my own progressive linkage pretty cheap. I started to run outta time and never got everything ironed out. I enjoy tinkering when it goes in my favor lol. This time it didnt. I pulled it off and put single 4bl back on. Next time it will go on with 273 as Commando, hopefully less time tinkering and more time giggling lol.
If you do it, I would say 85% for coolness.
CFD244 said:
@4spdragtop went down this road.......Maybe he will chime in with his experience.
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A few years ago I came across a Edelbrock tunnel ram with two 660 center squirters for a small block.

At the time I was running an Airgap with a Holley 750.

I thought I've got to give that a try on my '67 Barracuda with a stock 340. If I don't like it, I'll sell it.
I couldn't believe how much this woke my 340 up! It took a while to dial it in as I'm at 5K feet.

I drive it on the street as much as I can (not as much as I would like), I take it to work on occasion and that's 55 miles each way.

I installed a new 340 this spring that made 400 H / 400 T with a Holley 650 on the airgap.

These past few months I have run a vacuum and a mechanical six pack.

I have a 416 in the works that will have Indy 360-1 heads and have the matching single plane for it.

Guess which set up I've decided to stick with on the new build?

Yep, the tunnel ram and the 660's.

The six packs will be going up for sale in a few months but, I just had to try them as I have always wanted a 340 six pack.

The six packs are great, but it's hard to beat the tunnel ram in my book.

IMG_9281.jpeg


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I’m just trying to live my childhood dreams where it was cool to own a hot rod with dual quads on a tunnel ram. Now that I’m older this generation wants to talk about how cool Teslas are. I’m 44yrs old with an identity crisis, I wanted to grow up in 50’s, 60’s, and 70’s. When women, cars, and music was cool. Mid 70’s through the 80’s things really began to start sucking and now I’m just lost I don’t associate with anything thats going on. I need to finish my car so I can put down some rubber while listening to Led Zeppelin II.

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67/6barracuda said:
I’m just trying to live my childhood dreams where it was cool to own a hot rod with dual quads on a tunnel ram. Now that I’m older this generation wants to talk about how cool Teslas are. I’m 44yrs old with an identity crisis, I wanted to grow up in 50’s, 60’s, and 70’s. When women, cars, and music was cool. Mid 70’s through the 80’s things really began start sucking and now I’m just lost I don’t associate with anything thats going on. I need to finish my car so I can put down some rubber while listening to Led Zeppelin II.

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I hear you! I think most on this forum feel the same way.

I’m 62 and tell people that our bodies get older but we really never grow up.
( at least that’s how I feel when it comes to our cars)

My first car was a ‘69 340 Barracuda and I could hardly afford to put gas in the thing. My friends had 383 Darts and Hemi Roadrunners in high school.
 
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Dual Quads allow better fuel distribution because of the ability to jet for each cylinder. If you have headers with EGT's you can really fine tune the fuel system.

I also find that it allows for a lower idle speed, as well as, a smoother idle.

Tom
 
67/6barracuda said:
I’m just trying to live my childhood dreams where it was cool to own a hot rod with dual quads on a tunnel ram. Now that I’m older this generation wants to talk about how cool Teslas are. I’m 44yrs old with an identity crisis, I wanted to grow up in 50’s, 60’s, and 70’s. When women, cars, and music was cool. Mid 70’s through the 80’s things really began start sucking and now I’m just lost I don’t associate with anything thats going on. I need to finish my car so I can put down some rubber while listening to Led Zeppelin II.

View attachment 1716164108
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I'm 46 and feel the same way! That right there looks like "a while lotta love", and I bet she "rambles on" with a press of the loud pedal!
 
HankRearden said:
As far asI know the reason now days is just because cool.
But when multiple carbs became the hot ticket for performance in the 40's,50's and 60's you couldn't easily get a 1200 cm carb.
Click to expand...
Easily? You couldn’t till holley came out with the 3 barrel carbs sometime around 67-68 ish.
Up until that time it was 750 cfm.
 
coloradohill said:
A few years ago I came across a Edelbrock tunnel ram with two 660 center squirters for a small block.

At the time I was running an Airgap with a Holley 750.

I thought I've got to give that a try on my '67 Barracuda with a stock 340. If I don't like it, I'll sell it.
I couldn't believe how much this woke my 340 up! It took a while to dial it in as I'm at 5K feet.

I drive it on the street as much as I can (not as much as I would like), I take it to work on occasion and that's 55 miles each way.

I installed a new 340 this spring that made 400 H / 400 T with a Holley 650 on the airgap.

These past few months I have run a vacuum and a mechanical six pack.

I have a 416 in the works that will have Indy 360-1 heads and have the matching single plane for it.

Guess which set up I've decided to stick with on the new build?

Yep, the tunnel ram and the 660's.

The six packs will be going up for sale in a few months but, I just had to try them as I have always wanted a 340 six pack.

The six packs are great, but it's hard to beat the tunnel ram in my book.

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View attachment 1716164091
Click to expand...

Hayyyyyy, you got the cool mechanical set up!
Nice!
 
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