speed demon 650 carb ?
Thread Starter
Heel & Toe
Joined: Feb 2006
Posts: 15
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i have 1.6 roller rockers...i also have a 750 holley dp laying around...i am expecting around 400 hp. would i be better off going w/ the 750? i know that the jet sizes are about the same sizes on both of them. any advice would be appreciated.
Instructor
Joined: Apr 2004
Posts: 235
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From: Mansfield Ohio
Drifting
Joined: Jul 2002
Posts: 1,943
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From: Rosemount MN
Well lets start off saying it takes about 425-450 SCFM to make 400 HP. That's unencumbered flywheel HP (gross) not SAE (net) or RWHP.
That said, most builders will recomend using between 2/3 (429 SCFM) and 3/4 (487 SCFM) of a carburetors rated flow to calculate which carb to use.
OK that means that a 650 would be on the low to medium side for 400HP, but that would be it, the limit to your engine.
Tell us a little more about your heads, and cam.
That said, most builders will recomend using between 2/3 (429 SCFM) and 3/4 (487 SCFM) of a carburetors rated flow to calculate which carb to use.
OK that means that a 650 would be on the low to medium side for 400HP, but that would be it, the limit to your engine.
Tell us a little more about your heads, and cam.
Last edited by Tonys96; Sep 22, 2006 at 03:54 PM.
Burning Brakes
Joined: Apr 2000
Posts: 1,145
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Originally Posted by Tonys96
A better choice would be a 750, the 650 will most likely, depending on manifold choice be your limiting factor.
Cam is also pretty mild for a 383.
What are you expecting for HP 390 (300 RWHP) ?
Cam is also pretty mild for a 383.
What are you expecting for HP 390 (300 RWHP) ?
$250 + shipping.
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From: Cape Cod, Mass.
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I've got a 650 double pump Speed Demon on my 383 in my 61. It feels a little under carbeurated. If I had it to do over I would go with a 750. 
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