Re: Carb shopping
[Re: RobX4406]
#1726650
01/16/15 01:07 PM
01/16/15 01:07 PM
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Joined: Sep 2004
Posts: 6,906 IL, Aurora
ademon
master
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master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
Quote:
But this mechanical 6 pack setup replaced the 4bbl and single plane. The engine seems slightly stronger with the 6 pack even with the 1,150cfms and no jetting!
~813 cfm in 4 bbl terms.
No .. this is the mechanical setup sold in the late 70's early 80 through DC. The end carbs are a 850dp cut in half with slabbed throttle shafts and all. The middle is a 355cfm which I removed the choke plate and shaft.
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Re: Carb shopping
[Re: ademon]
#1726651
01/16/15 01:23 PM
01/16/15 01:23 PM
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Joined: Jan 2003
Posts: 6,266 Renton Washington
Triple Threat
master
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master
Joined: Jan 2003
Posts: 6,266
Renton Washington
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Mike,
I ran a 4150 750 HP on my old 340 back when the dart went 12.50's. I probably put 10,000 street miles on it without issue. It would get 14mpg if I kept my foot out of it.
-Dustin 67 Dart, 9 second, 392" G3 Hemi 68 Barracuda 340 F/SA
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Re: Carb shopping
[Re: RobX4406]
#1726652
01/16/15 01:41 PM
01/16/15 01:41 PM
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Joined: Feb 2003
Posts: 1,942 Metro Detroit
OUTLAWD
top fuel
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top fuel
Joined: Feb 2003
Posts: 1,942
Metro Detroit
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I would go with a 750 vac sec. maybe get an aftermarket main body with adjustable air bleeds and secondary metering block.
My experience with the HP carbs (950...not sure if the 750 HP is the same or not) is that they use different metering block, with idle restrictions, power valve restrictions and emulsion tuning that are tailored for the track, not the street. Great at WOT, but pig rich at part throttle out of the box.
Also with 3.23's I imagine tuning transitions would be a bit easier with a vacuum secondary
Faster, Faster until the thrill of speed overcomes the fear of death...
71 Swinger - slowly collecting dust/parts 66 Belv. II - just a streetcar 88 Mustang - turbo LS beater
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Re: Carb shopping
[Re: Street Monkies]
#1726653
01/16/15 06:09 PM
01/16/15 06:09 PM
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Joined: Mar 2005
Posts: 792 Earth
Rob C
super stock
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super stock
Joined: Mar 2005
Posts: 792
Earth
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Quote:
Right but if you look at it this way. A motor will only draw in so much cfm of the carburetor. It doesn't matter what carb, style, or model if motor only can take in 500 cfm and you use a 650 then what? Is it to big now? You can run any carb you want but if it's a street set up then who gives a turkey about size really lol. As long as motor is getting fuel and is working like it's supposed to.
I understand what your saying. The thing here is that it is not to big or oversized, the carb will work. In the case of a VC carb, it will only open up so much. In a DP carb, if the carb is to big, you'll probably have a slower car and or a soft bottom end and or middle.... The list carries on... If it is a 850 cdm carb on a 273, getting it even near right at idle will probably be... inventive on new cuss words. LOL
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Re: Carb shopping
[Re: VincentVega]
#1726654
01/16/15 06:10 PM
01/16/15 06:10 PM
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Joined: Mar 2005
Posts: 792 Earth
Rob C
super stock
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super stock
Joined: Mar 2005
Posts: 792
Earth
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Quote:
I'd love to own the competition series TQ (1000 cfm), but those are like hen's teeth
Keep your eyes open. Look to FABO's for sale section. One popped up not to long ago. Happy (carb) hunting!
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Re: Carb shopping
[Re: Rob C]
#1726656
01/16/15 09:15 PM
01/16/15 09:15 PM
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Joined: Sep 2004
Posts: 6,906 IL, Aurora
ademon
master
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master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
And Dog Days says this---> Quote:
Not that again! Two-barrel carbs are rated differently, you need to divide the two barrel rating by the square root of two (1.4142) to convert to a four barrel reading. For 1350 two barrel cfm that equates to 955 four barrel cfm. BUT, the carb setup opened the end carbs only as much as the engine needed so I don't think any stock 340 ever used all of the 6-pack capacity.
Not to start in and make a mess of things, but what is the conversion for the stock 6pack equal to in 4bbl. terms/cfm??
And the mechanical MP unit cfm rating in 4 bbl. terms?
Stock 6 pack I've always read and heard about 950cfm DC carbs have slabbed throttle shafts and thinner blades plus I'm pretty sure the Venturi is bigger on the end carbs. About 1,100cfm
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Re: Carb shopping
[Re: Stroker Scamp]
#1726657
01/16/15 11:00 PM
01/16/15 11:00 PM
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Joined: Jan 2003
Posts: 12,815 Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
Joined: Jan 2003
Posts: 12,815
Benton, IL.
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Quote:
340, larger than stock cam (no specs), RPM Air gap, stock bottom end, headers Looking for a Holley 750 double pumper I think I have it narrowed down to the 4150 Street HP, anyone run this carb on a mostly street driven car?? Opinions
Opinions are all over the place, aren't they? One important piece of information that carb questions should include is the OP's desire and/or ability to properly tune the carb. And also, what's more important to you; maximum performance or maximum drive-ability?
Most guys are not carb tuners and don't have the wide band, drill bits, jets, bleeds or knowledge of the carb's circuits to get the most out of their choice of carb. For them, the carb that comes out of the box closest to the design and tune that their combination likes, is usually the best choice. Or at least the best starting point.
There are a lot of different configurations of 750 cfm carbs. All of them will run your car, but some will do a better job ON YOUR COMBO than others. But that doesn't necessarily mean one is actually better than the others, just maybe that it is closer to the tune that you combo likes.
A good tuner with the proper tools and experience can start with most any 750 and get it to rock. But the farther away from the combo's preferred tune the carb is, the more changes the tuner has to do to get it right. So whether an experienced tuner or not, it is best to start with the carb that is closest to the tune that your combo wants.
And irregardless of the tune, some carb configurations are designed to do one job better than another. Like spread bore or square bore, mech secondaries or vacuum, annular or down leg boosters and on and on.
Sorry for the long response. But carb selection is as complicated as cam selection. Most guys turn to a cam grinder for recommendations. And any cam guy worthy of your money will want A LOT of info on the engine, drive train and the customer's desires before he makes a recommendation.
In order to get the optimum carb, the same approach should be taken. How about asking Thumper to set one up for you? Tell him what you want and what your combo is and let him pick the platform and through his tune in it. That would likely get you a better carb than the one ordered by a catalog number.
Master, again and still
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Re: Carb shopping
[Re: Thumperdart]
#1726659
01/17/15 01:50 AM
01/17/15 01:50 AM
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Joined: Jan 2003
Posts: 5,487 SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,487
SoCal
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Holley 650 ultra double pumper...best carb OOTB for your application.
Brian Hafliger
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