Re: 440 Six Pack carb questions
[Re: lewtot184]
#1357604
12/23/12 02:17 PM
12/23/12 02:17 PM
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Joined: Nov 2011
Posts: 238
Florida, US
72ls5fla
enthusiast
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enthusiast
Joined: Nov 2011
Posts: 238
Florida, US
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I seemed to remember the center flowing around 350 CFM ....
The end carbs maybe 400 CFM each .....
I think 1350 is to high of a number.
Got me a NEW Project
1970 GTX 440+6, 4 spd, 4.10 Dana and N96 FE5 (top/bottom) and black bucket interior.
Original transmission and Dana - Engine is a service replacement block.
Body has all stamped #s + VIN/TRIM tag and door sticker. Been hunting like all hell to find the Build Sheet.
garage find, only had 41,850 miles on ODO.
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Re: 440 Six Pack carb questions
[Re: mikemee1331]
#1357607
12/23/12 04:21 PM
12/23/12 04:21 PM
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Joined: Jul 2011
Posts: 957
Chicago
PurpleBeeper
super stock
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super stock
Joined: Jul 2011
Posts: 957
Chicago
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Here's the deal... the outboard carbs are both rated at 500cfm and the center carb is rated at 350cfm for a total of 1350cfm. However... 2-barrels flow are rated differently (more favorably) than 4-barrels (something about pressure drop and inches of mercury I can't exactly recall). So, to compare 2bbls. to 4bbs. directly you have to make a calculation adjustment.
Here's a quote from someone much smarter than me:
To convert: multiply 2 bbl. rating by 70.71% to get flow at the 1.5" (lower) vacuum 4 bbl. rating. Multiply the 4 bbl. rating by 141.4% to get the 3" 2 bbl. rating. The formula is simple:
New flow rate = (new vacuum level ÷ old vacuum level)^.5 × old flow rate
500 2 bbl. flows 353.55 CFM at the 1.5" vacuum level.
Another way to look at this is multiply the 2bbl rating x 0.7071
So 1350 x 0.7071 = roughly 955 cfm for a six pack in 4bbl. terms.
70 Roadrunner convt. street car
440+6, NOS, 4-spd, SS springs
'96 Mustang GT convt. street car
'04 4.6 SOHC, NOS, auto, lowered
"Officer, that button is for short on-ramps"
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Re: 440 Six Pack carb questions
[Re: B5 Bee]
#1357608
12/23/12 06:03 PM
12/23/12 06:03 PM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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Quote:
Holley rates 2bbls differently. The 2bbl rating for the Six Pack is 1350, 2x500 outboards, 350 center.
To get an idea of the outboard flow rated like a 4bbl, the throttle bore and venturi is the same as a 750DP. So just the 2 outboards total 750cfm. The center 350 is estimated to have a 4bbl rating of 230-240.
Total Six Pack flow is 980-990.
venturi and throttle bore sizes for the end carbs is the same as an 850 4bbl; 1 9/16" venturi and 1 3/4" throttle bores. the original end carbs were rated at 390cfm each. the center was 250cfm.
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Re: 440 Six Pack carb questions
[Re: lewtot184]
#1357609
12/23/12 07:41 PM
12/23/12 07:41 PM
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Joined: Feb 2003
Posts: 8,020
Pangaea
B5 Bee
master
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master
Joined: Feb 2003
Posts: 8,020
Pangaea
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Quote:
Quote:
Holley rates 2bbls differently. The 2bbl rating for the Six Pack is 1350, 2x500 outboards, 350 center.
To get an idea of the outboard flow rated like a 4bbl, the throttle bore and venturi is the same as a 750DP. So just the 2 outboards total 750cfm. The center 350 is estimated to have a 4bbl rating of 230-240.
Total Six Pack flow is 980-990.
venturi and throttle bore sizes for the end carbs is the same as an 850 4bbl; 1 9/16" venturi and 1 3/4" throttle bores. the original end carbs were rated at 390cfm each. the center was 250cfm.
I stand corrected, I just measured an end carb. The throttle bores are 1 3/4" but the venturi is not 1 9/16", it's 1 7/16".
Holley made a 2300 carb with the same specs and it was rated 650cfm. The #6425 attained a big part of it's 650cfm flow from the lack of boosters.
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Re: 440 Six Pack carb questions
[Re: B5 Bee]
#1357610
12/23/12 08:37 PM
12/23/12 08:37 PM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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Quote:
Quote:
Quote:
Holley rates 2bbls differently. The 2bbl rating for the Six Pack is 1350, 2x500 outboards, 350 center.
To get an idea of the outboard flow rated like a 4bbl, the throttle bore and venturi is the same as a 750DP. So just the 2 outboards total 750cfm. The center 350 is estimated to have a 4bbl rating of 230-240.
Total Six Pack flow is 980-990.
venturi and throttle bore sizes for the end carbs is the same as an 850 4bbl; 1 9/16" venturi and 1 3/4" throttle bores. the original end carbs were rated at 390cfm each. the center was 250cfm.
I stand corrected, I just measured an end carb. The throttle bores are 1 3/4" but the venturi is not 1 9/16", it's 1 7/16".
Holley made a 2300 carb with the same specs and it was rated 650cfm. The #6425 attained a big part of it's 650cfm flow from the lack of boosters.
the carb in the picture isn't mopar. it was a very special 2bbl for the guys who had to run "2bbl only" classes, like in roundy-round racing. they're kinda rare. fuel comes out of the venturi walls rather than thru a booster. eliminating the booster allowed for greater air flow.
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