Carb size

[MoparCain]

Put one of these on it.

 

[khryslerkid]

You want something that'll make it run like hell? Put one of these on it. They act smaller than they are at part throttle allowing good street manners but will blow your mind when you bend the floorboard. http://www.summitracing.com/parts/hly-0-80805bk

Check out the CFM calculator on that page also..

 

[451Mopar]

I have been using an old Holley HP 1,000 cfm vacuum secondary carb. I no longer see a listing for it on Holleys web site, but it has the annular boosters and is very responsive. It replaced an 850 DP carb and it was more responsive and about 0.1 sec quicker on my 11:1 compression 451 engine.

 

[womanator]

Run what you have.
67 Dart.
446 ci.
Hughs .590 cam
Eldelbrock heads ported.
M-1 intake.
3500 conveter.
Well built trans.
4.10 gears.

750 dp Holley.

Runs 10.71 in the 1/4. off the juice.
Very good street manners.

Forgot to say it's a Pump gas street driven car.

Yes I know I could go faster with a bigger carb.
But this one has GREAT street manners.

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I don't know how fast you are running,but more people over carb there rides.

But 10.71 on street tire's and a 750 Holley.

This says a lot.
Maybe there's more in your tune

 

[68 HEMI GTS]

Run what you have.
67 Dart.
446 ci.
Hughs .590 cam
Eldelbrock heads ported.
M-1 intake.
3500 conveter.
Well built trans.
4.10 gears.

750 dp Holley.

Runs 10.71 in the 1/4. off the juice.
Very good street manners.

Forgot to say it's a Pump gas street driven car.

Yes I know I could go faster with a bigger carb.
But this one has GREAT street manners.

- - - Updated - - -

I don't know how fast you are running,but more people over carb there rides.

But 10.71 on street tire's and a 750 Holley.

This says a lot.
Maybe there's more in your tune

i still got a thing for that car..

 

[68 Sport Satellite]

I have been using an old Holley HP 1,000 cfm vacuum secondary carb. I no longer see a listing for it on Holleys web site, but it has the annular boosters and is very responsive. It replaced an 850 DP carb and it was more responsive and about 0.1 sec quicker on my 11:1 compression 451 engine.

can you clarify which was more responsive on your 451 - the 850 DP or the 1000? That 11:1 compression is a bit high for running 91 octane pump gas though...

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Sounds like the QuickFuel 780 I had in mind may work out just fine....

 

[MikeyT]

MP would say go with a 850 cfm holley. I hoever run a 750 Db pumper on my 440 and it is very similar to your build. My key was paying the 75 dollars to get it on aq chassis dyno and tune it that way.

Mike

 

[RustyRatRod]

Show off. lol

Run what you have.
67 Dart.
446 ci.
Hughs .590 cam
Eldelbrock heads ported.
M-1 intake.
3500 conveter.
Well built trans.
4.10 gears.

750 dp Holley.

Runs 10.71 in the 1/4. off the juice.
Very good street manners.

Forgot to say it's a Pump gas street driven car.

Yes I know I could go faster with a bigger carb.
But this one has GREAT street manners.

- - - Updated - - -

I don't know how fast you are running,but more people over carb there rides.

But 10.71 on street tire's and a 750 Holley.

This says a lot.
Maybe there's more in your tune

 

[womanator]

Just the fact's.LOL
If you show prof it leave little to the imagination.
This engine also has 11-1 comp.

 

[cwhubb]

@ Rusty, the velocity dynamic has me thinking... how do you figure cfm when you have a nice set of high flow high velocity heads? add the intake manifold flow on top of that and it seems that would render the the cfm calculator formula irrevelant

 

[RustyRatRod]

Listen to womanator. "run what you have". That's sound advice. He's runnin 10s with "just" a 750. Most folks tryin to run those times would go bigger. Keep it simple. It's easy to get overcome thinkin about numbers.

 

[cwhubb]

hell yea it is

 

[Cranky]

Without reading this whole thread, I like to experiment and use the track as my dyno but in your case since it's a street car mainly (right?), I'd tend to stay on the small side unless on the other hand you want to go deeper (since you have a fairly large cam and heads), I would tend to go on the bigger side for my junk which is usually on the street but also goes to the track. With that cam, heads etc, I would say you are trying to go very low 11s or better depending on your traction, gears, converter, suspension etc. IMO, you don't have a daily driver but a hot rod that you drive daily. There is a difference. Again, IMO, daily drivers are closer to stock with mild cams, stock but mildly ported heads, headers, 2500-2700 stall converters, some gear, better built transmissions, smaller carbs for better off the line acceleration etc, etc....

 

[Budnicks]

IMHFO just because it's called a "750cfm" DP Holley or whomever's carburetor your using, doesn't always mean "that is what it flows" either...LOL... I had a pair of trick 750cfm Quickfuel carbs, that when bench tested, they each flowed nearly 880cfm {+ or - a cfm or 2}, it can be deceiving sometime, what some people will tell us & what is actual reality...

 

[cwhubb]

when you say trick do you mean they were tweaked or souped up from the out of the box condition?

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judas Priest Maury! why cant the carb people just list the true cfm

 

[440+6]

IMHFO just because it's called a "750cfm" DP Holley or whomever's carburetor your using, doesn't always mean "that is what it flows" either...LOL... I had a pair of trick 750cfm Quickfuel carbs, that when bench tested, they each flowed nearly 880cfm {+ or - a cfm or 2}, it can be deceiving sometime, what some people will tell us & what is actual reality...

Like the holly six pack claim 1350 cfm but if measured like 4 barrels are its around 950 cfm and I have no idea what they would actually flow.

you would thing these numbers would be pretty close to reality these days and standardized but they aren't.

 

[Budnicks]

when you say trick do you mean they were tweaked or souped up from the out of the box condition?

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judas Priest Maury! why cant the carb people just list the true cfm

Trick "yes" souped up out of the box, not the typical parts store carburetors !!... Quickfuel Technologies, AED, Proform, Promax, Holley HP, Demon & many others, they do many things to improve cfm flow... remove the choke horn, polish throats, main body design changes, style of venturies & boostes even, base plates, throttle blades shaft sizes, spacers etc. among many, many other things, can & will effect actual cfm flow... Also sometimes cfm/carb size can be based on size/diameter of throttle blades & not actual final cfm flow...

 

[cwhubb]

I talked to a holley tech the other day, all their carbs and pretty much everyone elses cfm is rated @ dry flow so the 950hp is a little less than an 850, 850 closer to 750 so on and so on. the holley hp ultras are wet flowed and are the only holleys that have accurate cfm numbers

 

[Budnicks]

@ Rusty, the velocity dynamic has me thinking... how do you figure cfm when you have a nice set of high flow high velocity heads? add the intake manifold flow on top of that and it seems that would render the the cfm calculator formula irrevelant

Cubic Inches x RPM divided by 3456 = CFM... It's just a decent guide line, not the gospal... many other factors will/can come into play, but for a basic performance modded street/strip car, a basic 2 cfm/per cubic inch, is a decent rule of thumb also... If you have high compression, long stroke, big bore/bore size period, big roller camshaft & what duration/what lifts, larger valves, longer rocker ratios, small combustion chambers or open combustion chambers, angle the valve is at in the heads, what type/style of exhaust can & will effect flow too{what goes in must come out}, Hemi or Wedge heads {even what material the heads are made of can effect flow/efficiency}, or even efficiency of the flow, raised intake or exhaust ports, shape of intake & exhaust ports, professionally ported &/or polished cylinder heads, ported intake manifold, dual plane or single plane intake manifold, what carburetor set up to be used, will it be a 2 bbl or 4bbl or 6bbl or 2x4bbls or 4x2bbls {like split Dominators} or injetected, then what type of injection mechanical or EFI, a TB or a hat on a tunnel ram or individual stacks etc., if a spacer will be used under the carburetor, how tall or even what type of spacer used, whether it's a tapered open spacer or 4 port & tapered spacer, whether it's on a tunnel ram or individual stacks like FI, that all can flow way beyond stock, the formula doesn't apply very well after that point, you need to know, how fast you want to go, what is the intended usage, how to read your plugs & adjust the carburetor for altitudes &/or track & weather conditions {or street driving}, type of fuel delivery used, type of fuel used, type of base plates, size of squirter's, size/style of booster, size of venturies, polished or not, size of throttle plates & even the shaft sizes {all thes can/will effect flow/cfm}, whether you use a velocity stack or short stack, if it's going to be ram air/forced induction or not, what type of filter & what style of air cleaner base & top is used even, what power valve or blocked off & no power valve, the size of air bleeds, the type/style & size of metering blocks, size of jets, jet extensions, 50cc acc. pumps, different colored pump cams that affect the way the fuel is delivered... allot of trial & error allot of variable to factor in too, way more than just cfm flow, I'm sure there are more things, like type of ignition, gears or trans type, weight of car, wheter it's a vacuum secondary or a double pumper used etc... My long winded post is basically meant to say, there's no one formula, that is absolutely correct, for all combos... for drag racing, the wide open full throttle flow, is more important than just throttle resonse & throttle resonse is more important than wide open throttle on a road course car, no one cfm or carburetor style is ideal for everything...