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Discussion Starter #1
I have been researching Holley carbs lately.

Here are some things I have come up with:
Downleg boosters are less of a restriction than the straight tube boosters, and therefore allow more CFMs to flow through the carb.

Bigger venturis flow more air.

Bigger throttle plates flow more air.

Pretty basic.

Here is the Holley link for their carb ratings, #s, and specs.
http://www.holley.com/HiOctn/ProdLine/CarbList.pdf

Use the magnifying glass icon at the top to enlarge the chart.

If you look at the difference between the 3310-1 and the 3310-2 it is obvious from the chart that the -1 is 30 CFMs more. This is because of the fact that the -1 has downleg boosters. Simple enough.

Now look to the right of the chart and you will see Venturi diameter for the primary and secondary bores. There are also measurements for the throttle bores.

So the 3310-1 is 780 CFMs. We know that. Again, because of the downlegs. It has 1 3/8" primary venturis and 1 7/16" secondaries. The throttle bores are 1 11/16"

Now, scroll down to the #80531 850 CFM carb. 1 3/8" primaries and 1 3/8" secondaries? You can't see it there, but it also has downleg boosters. WTF?

Another good comparison is the 4781 850 CFM carb and the 80513 1,000 CFM carb. Now the 1,000 carb does have the HP style contoured top, but I know for a fact that contouring doesn't account for 150 CFMs.

Here is a link that discusses this subject a little. Very little.
http://www.thecarburetorshop.net/technical.html

Anybody have any input? Any links to show what all of the carbs really flow. I have been trying to find the optimum carb for my engine. This kind of put a speedbump in the way.
 

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" I have been trying to find the optimum carb for my engine"


lol
stop screwing round
why dont ya put your knowledge to work and build a fast car....????? ya definatly got the knowhow.....??? bunghole.....:D
 

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Discussion Starter #3
Cause I got to drive it to work everyday. Don't want to be rollin' up to work in no popcorn machine. You know what I mean?
 

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Discussion Starter #5
WICKEDFAB said:
yeah........lol

build anotha.......stop wasting $$$ on the driver.....:cool:
I have another but I am going to be selling it. The 5.0, '61 Ranchero.

A guy I work with has been to your shop. I can't remember if he had work done to his '69 Nova, or if it was his truck.
 

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Technical Support Barry Grant
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Real world flow numbers

You're going to run into a few problems with this.

One Holley has flow rated their carburetors differently over the years depending on marketing.

Two, and more importantly unless you're flowing them on the same flow bench (with the same parameters) or on the same engine it's not going to be a valid comparison.

Lastly, (and most important) actual air flow will be dependent on the engine combination itself, not the carburetor.

What are you trying to determine?
 
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