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Discussion Starter #1
Me and the dad finally got our new motor going, 383, eagle forged rotating assembly, dart pro1 215cc, .543/.561 solid roller. My first question is about the Proform main body on the holley 650, Proform claims it flows 750 plus cfm, does the main body really turn my 650 into a 750? The second question is the oil pressure, all warmed up at cruise it gets about 50 psi, at 1000 rpm idle we get about 18 psi, is that about the norm? Can't wait to 1320 her, I'm sure we'll be pleased after being used to the old, tired, loose, oil burning 327 that is now sitting in the basement.
 

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The Porform main body will replace the body on 650 and 750 carbs. If your using the base plate off a 650, then you still have a 650. The butterflys are different sizes on the 2 carbs. The addition of the proform main body will more than likely let your engine breath a little better than the stock 650 did. A carb will flowas much air as the engine needs, the carb is the restriction in the intake system. The bigger the carb the less the restriction. You need the carb to be a very small restriction to get the pull on the boosters just right, but not big enough of a restriction to limit the engine's horsepower potential by having to pull too hard on the carb. Your 383 at 6000 rpm's would need 665cfm at 100% volumetric efficency. At 90% (more common for a street engine) it would need 598cfm, so your 650 with the Proform main body should be just right. Also your oil pressure seems fine to me.
 

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Discussion Starter #4
Thanks for the info guys, greatly appreciated.:D
 

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650 ,700,750.800 use same baseplate

650 base plate will work on the Proform body , it uses the same 1 11/16 throttle blades , throttle body as the 750 or even 800 and 700. I'm sure different jetting will be required in the metering blocks but the idle circuit restriction should be the same in the 650 metering blocks as a 750 , I think ,,
 

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As stated above, the throttle body butterflys are the exact same on 650 and 750. They are both 1 11/16 on primary and secondary sides.The difference between the 650 and 750 is the Venturi diameters. On the 650 it's 1 1/4 on the primary and 1 5/16 on the secondary side. On the 750 both primarys and secondarys are 1 3/8. Since you switched out the main bodies you now have a 750. I have been wanting to buy one of those pro form bodies for mine, I'm running a 650. Let us know how it runs, and if you are pleased with it.
 

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I moved this to the drivetrain and performance section because it is about carbs and oil pressure, not really drag racing.
 
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