Speed Demon 650 or 750 for this setup?

allcarfan

The Answer Man

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Apr 8, 2001

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#1

• Dec 10, 2003

• #1

lightweight 331 stroker
Mildly ported twisted wedge heads (290/210cfm)
xe274hr cam:
* Advertised duration: 274 intake/282 exhaust
* Duration at .050 in.: 224 intake/232 exhaust
* Gross valve lift: .555 in. intake/.565 in. exhaust
* Lobe separation: 112 degrees
Ported and notched Performer RPM intake
1 3/4" headers

Engine will probably see 6700 rpms or so once in a while.

So...Speed demon 650 or 750?

I read an article where an engine made 400 at the flywheel and the 750 speed demon was too big.

Shane

 

M

matm347

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Aug 29, 2000

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#2

• Dec 10, 2003

• #2

You should see a little more than 400 FWHP, but I would go with the 650 and tinker with it(different jettings/spacers). I read in an article of a company that makes spacers that increase the cfm by ~30 and add a good amount of power across the range, I think it was in the new 5.0 issue.

 

StangYellow

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Sep 11, 2002

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There was an article in a recent Car Craft where they made a 302 dyno 401fwhp. But the car revved to the moon and they did use a 750cfm carb. Im not sure why, but they did. I would stick with a 650 carb if it was my car. Good luck.

 

blown5.0

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#4

• Dec 10, 2003

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650 carb all the way. and yes those carb spacers are tapper inside to provide a smooth airflow from the carb to the intake, sort of like port matching, and the tappered carb spacers add a good amount of hp.

 

allcarfan

The Answer Man

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#5

• Dec 10, 2003

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StangYellow said:

There was an article in a recent Car Craft where they made a 302 dyno 401fwhp. But the car revved to the moon and they did use a 750cfm carb. Im not sure why, but they did. I would stick with a 650 carb if it was my car. Good luck.

Click to expand...

FYI...the speed demon 650cfm carb wet flows more than a holley 4160 (750cfm) carb

Shane