Another Carb size thread?? 570 or 670 Street Avenger?

84convertablegt

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Dec 7, 2008

#1

• Dec 7, 2008

• #1

I've read and read and searched and searched and I can't make up my mind. I've ran the Holley S.A. 670 on 2 stock 302's and they both ran good, even though I know they were over carbed with that 670.

On my current 64.5 Mustang, I am trying to figure out which one to go with. Here's my setup.
-Stock 65 289 block
-AFR 165 Aluminum heads
-Comp Cams 268HE cam
-Cobra stage 2 289 intake
-C4 Auto (stock stall)
-Stock rear gears (for now)

Should I go with the 570 or 670 street avenger? The holley website recommends both, and the 80457 600cfm 4160, which I don't care for. I would think the 570 would give better throttle response, I'm just afraid of running out of steam with the AFR heads and cam.

Please give me a recommendation based on experience and carburetor expertise, not just because you've had one or the other. Thanks

 

D

D.Hearne

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#2

• Dec 7, 2008

• #2

Cobra Stage II intake? Where'd that come from? Run the 670. Or if you prefer the classic Holley look, the 80783 650 VS. This is basically the 670 but with the older finish

 

84convertablegt

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#3

• Dec 7, 2008

• #3

D.Hearne said:

Cobra Stage II intake? Where'd that come from? Run the 670. Or if you prefer the classic Holley look, the 80783 650 VS. This is basically the 670 but with the older finish

Click to expand...

The Cobra intake I'm referring to is the repro 289 Hipo manifold. I guess "stage 2" was my substitution for "hi rise dual plane". I'll have to check out the 80783. Does it have the same jets?

 

D

D.Hearne

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#4

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If not the same jetting, it'll be within a size or two. Doesn't matter anyway in that regard, you can always change that if need be. The O.E. Hi-po manifold was the same low-rise iron unit the std 289 4bbl's had. The "Cobra" aluminum high rise is just one version of several, the others being the C9OX, Edelbrock F4B and the current Ford Racing A321. Weiand's older Stealth was a mirror image of these wth runners reversed as opposed to the layout of the others.

 

rbohm

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tucson,az

Dec 7, 2008

#5

• Dec 7, 2008

• #5

my recommendation would to use the 670 street avenger carb with your combination. you wont notice any loss in low end response, and you will notice a slight gain in top end power. fuel economy will be about the same with either carb. oddly enough i am going to be running a slightly more radical combination than yours, but i am going to use a 480cfm autolight carb because i want the added fuel economy. i may swap later to a 500cfm edelbrock carb though if the autolite doesnt work as well as i think it might.

 

Decurion

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Dec 7, 2008

#6

• Dec 7, 2008

• #6

With your stock stall and stock gears (2.79?), Ill say go with the 570. Ill also say go with an Edelbrock Performer RPM or RPM Air Gap intake. From what Ive seen, they flow among the best for a dual plane without giving up any low end power.

 

84convertablegt

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#7

• Dec 7, 2008

• #7

D.Hearne said:

The "Cobra" aluminum high rise is just one version of several, the others being the C9OX, Edelbrock F4B and the current Ford Racing A321. Weiand's older Stealth was a mirror image of these wth runners reversed as opposed to the layout of the others.

Click to expand...

You know what I meant. I have the "Cobra" high rise. At any rate, I just spent $300 on my new SA670 on ebay, so I should be up and running in about a week.

Decurion said:

Ill also say go with an Edelbrock Performer RPM or RPM Air Gap intake .

Click to expand...

The intake I have is very similar to the Performer RPM. Just like D.Hearne said, many different intakes, all similar. The RPM is Edelbrocks newer version of the F4B. They are all hi rise dual plane aluminum manifolds.

 

D

D.Hearne

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Dec 8, 2008

#8

• Dec 8, 2008

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The RPM isn't a newer version of the F4B. True, they're both high rise dual planes, but they have different runner layouts. The Cobra HR & the F4B have unequal length runners where the RPM's have equal length runners.

 

84convertablegt

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Dec 8, 2008

#9

• Dec 8, 2008

• #9

wow

 

Decurion

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#10

• Dec 8, 2008

• #10

84convertablegt said:

The intake I have is very similar to the Performer RPM. Just like D.Hearne said, many different intakes, all similar. The RPM is Edelbrocks newer version of the F4B. They are all hi rise dual plane aluminum manifolds.

Click to expand...

Similar maybe, but I bet you would pick up at least 10lb-ft of torque right off idle, and at least as much horsepower (probably more) all the way to redline with either of the RPM intakes, more with the air gap.