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Dual carbs cfms?

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MoritSS

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Discussion starter · #1 ·
Hey
Lets say that according to simple math I need a 900cfm carb.
If I am to use dual carb setup what will I need, two 450cfm carbs?
Or there is something more to it?

Any good carbs that will work in pair that will not eat my budget?
600HP NA, tunnel ram. I heard something about summit tunnel ram combo not being good?
 
#2 ·
MoritSS said:
Hey
Lets say that according to simple math I need a 900cfm carb.
If I am to use dual carb setup what will I need, two 450cfm carbs?
Or there is something more to it?
Any good carbs that will work in pair that will not eat my budget?
600HP NA, tunnel ram. I heard something about summit tunnel ram combo not being good?
Click to expand...
You will not size the two carbs for the 900 cfm. Some thought needs to apply on how you intend to use the engine. Street? or race only? The duel carbs will flow as much air through them as the engine will flow.

If you intend to street mostly you will be concerned about air speed at lower RPM's for drive ability.

Example, years ago when I was running a race only 394 ci SBC it flowed around 930 cfm through the engine. I ran duel 1050 cfm dominators on it and it ran very well.

Blessings..........Ron
 
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Discussion starter · #3 ·
Hmm.. I am building 406 sbc with about 600HP and 550tq, 11.5:1 CR, top rpms at about 7000.
Still considering will it be hydraulic or solid (both roller).
I am building a race car for track and quarter mile, but the truth is that it will be used 98% on the streets, and it will be hopely used more then only at the weekends.

So what is the answer? Considering that what I told above, will I need two 450cfm carbs (which would be probably very street friendly)?
Or maybe two 600cfm might also be possible (which would be less street friendly and more race friendly..) ?

And I do not get at all whats the theory behind the fact that you engine flows 930cfms and you gave it two 1050cfm carbs..
Why isnt it an overkill??
 
#4 ·
something that works most of the time is to just use two 660holley centersquirters. i prefer to look at tunnelrams as I.R systems with a plenum just to even out the pulses that the traditional carbs have so much trouble with.
 
#8 ·
"much cheaper then anything else" thats the first warningsign to me. its not that those600vacum carbs are bad carbs its just that buying things twice cost more money then buying right in the first place and when it comes to tunnelrams 660´s have been around forewer and are a timetested option.
 
#9 ·
do it right the first time! spend the money for better carbs and avoid some head aches. 660 center squirters.
 
Discussion starter · #11 · (Edited)
Any link to those? Cant find part numbers.

EDIT:
Holley 0-4224? It is said that secondarys are mechanical.
Doesnt centersquirters have none secondarys?
Also If they do, dont I want vacuum on the street?
And I hate carbs without choke, but ok, Ill live with that :p
 
#12 ·
Dual carbs will flatten out the torque curve but you can go just as fast with a single carb.

For drag race only, ignore the "carb formulas" That's only good for a street application. I've seen a 434 SBC with dual 1050's on it. My 540 has had dual 850 alcohol carbs and I now run dual 4.1" toilets (1800 CFM each)
 
Discussion starter · #13 ·
The idea is to build a tunnel ram sbc with dual carbs. So there is a must to use two carbs. Becouse thats the idea ;)

The car will be used mostly on the streets. But track and drag racing (in that order) will show how well is the car (engine)build.
By the way, it is a 3gen Firebird which had poor 2.8l V6 stock :) Then I changed it to 350.. And after I've been picking my piston and block parts from the floor it is time to do it better way ;)
 
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MoritSS
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