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Carburetor Question
#1
What size carb would a quench 351C 4V have come with from the
factory? If you do the math for a 351, 600 cfm is within range.
But the Cleveland is half 351 and half 429, how does that alter
the math? My current is a Holley 670, 80670 Avenger. The Boss 302
came with a 750, I think. It has been decided we don't need headers
so the next best option is the appropriate carb size for optimizing
this cars performance. We are going to stay with Holley's 4150 style
Avenger system and vacuum secondaries.

mike

[Image: 1_11_11_13_11_50_27.png]
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#2
The 4300D that my car came with is 750 cfm. I think all Q and R codes in 72 were that size.
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#3
Mike, The original would have been 600 cfm according to everything I've read back in the day and recently. The 670 should work well for what you are doing IF you got a good one. I've used two of these in the last several years. One good, the other was returned because there was no way to make it idle. Holley did an exchange. The carb on the Boss 302 was rated at 780 cfm. The only reason the 780 worked reasonably well on the B2 was it was vacuum secondaries with the purple spring causing the secondaries not to open fully, if at all, until way after the factory rev limiter engaged. Chuck
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#4
A 71 M-code standard trans car came from the factory with a D1OF EA carb. The same car with an auto came with either a D1OF FA or a D1OF AAA. These were 605 cfm carbs.

http://mustangtek.com/4300/4300.html


.

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My Mustangs:
71 M-code Mach 1, Medium Blue/White Sport, 4R70W, 3L50, Factory Ram Air.
72 Q-code Mach 1, Pewter/Black Sport, 4-spd, 3L25.
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#5
c9zx;64639 Wrote:The 670 should work well for what you are doing
Agreed..670 should be just fine..I recently installed a S A 670 vacuum secondaries..on my camaro..going DOWN from the 750 that was installed..A quick tune with the vacuum gauge ..100% improvement all around..great carb
Depending on the flange you could have a 600 cfm as stated or a 715 cfm
http://mustangtek.com/carburetors/FordCarburetors.htm
http://mustangtimes.net/33-11/pg48-50.pdf

LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#6
For what it is worth:

351 Cubic Inch
0.203 Cubic Feet( CI/(12x12x12) ) (About 1.6 gallons if fluid)

6000 RPM At Crank
3000 RPM At Intake(Crank RPM/2)(Lots of people forget this)
610 CFM ( CF x RPM)
0.8 Inefficiency Reduction Between Piston and Carb
487 Net CFM( CFM x Inefficiency )

302 Cubic Inch
0.175 Cubic Feet
6000 RPM At Crank
3000 RPM At Intake
524 CFM
0.8 Inefficiency Reduction Between Piston and Carb
419 Net CFM

429 Cubic Inch
0.248 Cubic Feet
6000 RPM At Crank
3000 RPM At Intake
744 CFM
0.8 Inefficiency Reduction Between Piston and Carb
595 Net CFM

[Image: 11jmcuc.png]
351C Bold Manners, Brash Attitude
Favorite Teams: Michigan Wolverines and Whoever Is Playing Ohio State.

When I drive past a herd of cows, the cows MOO at me
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#7
goodnigh;64629 Wrote:What size carb would a quench 351C 4V have come with from the
factory? If you do the math for a 351, 600 cfm is within range.
But the Cleveland is half 351 and half 429, how does that alter
the math? My current is a Holley 670, 80670 Avenger. The Boss 302
came with a 750, I think. It has been decided we don't need headers
so the next best option is the appropriate carb size for optimizing
this cars performance. We are going to stay with Holley's 4150 style
Avenger system and vacuum secondaries.

mike

i still have my stock carb...Its a 4300D ..715cfm spread-bore ...i have a 1973 ..351 cobrajet 4v open chambered heads....Im pretty sure all 4300d's where 715cfm..Even the boss...But i cant say for sure...mine is.....and alot of sites state the same.
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#8
Here are the specs for the 4300d in 72.


Attached Files
.pdf   72 4300 D specs.pdf (Size: 473.22 KB / Downloads: 17)
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#9
Here are the specs for all 4V carbs offered by Ford in 1970 and 1971 as well.

Autolite, Holley, Rochester Quadrajet.

My 1973 shop manual does not have carburetor specification or I would have included those as well. Not sure why it doesn't have them.




.pdf   1970_4VCarbsAutoliteHolleyRochesterSpecs.pdf (Size: 1.28 MB / Downloads: 8)


Attached Files
.pdf   1971_4VCarbsAutoliteHolleyRochester.pdf (Size: 1.68 MB / Downloads: 8)

[Image: 11jmcuc.png]
351C Bold Manners, Brash Attitude
Favorite Teams: Michigan Wolverines and Whoever Is Playing Ohio State.

When I drive past a herd of cows, the cows MOO at me
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#10
The Boss 351 and the HO in 1972 both used a 715 CFM carb an Autolite 4300D. Over the counte a 780 CFM carb and intake combo was a common upgrade.

I'm running a 700 double pumper and It works very, very well, but I believe a 351 can use more maybe even 850 cfm with a solid lifter aggressive cam and a 7000 rpm redline, all of which are easy to do in a cleveland

A single intake valve flows 300 plus CFM at maximum lift which is 50 % more than other comparable sized v-8's, considering that the VE is either well over 100 or cylinder head flow is 50 % higher so the carb should be 50% bigger so a 650 may be fine on a 351 Windsor, but on a cleveland it will not allow maximum RPM's or power in my opinion

If I were starting from scratch I'd try a 750, but I think mine can use more than 50 CFM additional air flow

also keep in mind cfm ratings without a reference to inches of vacuum do not allow accurate comparison,

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"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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