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Its time I gave the old Iron manifold the heave ho and throw a new alum on
Question is which one? a 428/390 HP stock motor only upgades are Headers
and MSD Ignition. I was thinking prob Edelbrock Performer Rpm ,any other
ideas? I`ll be putting a 750 Holley or 750 edelbrock back on it
Depends on your rpm range.....
PERFORMER® MANIFOLDS (Idle to 5500 rpm)
PERFORMER RPM™ MANIFOLDS (1500 to 6500 rpm)
The rpm runners will be higher volume and are intended for use in a higher rpm motor where runner velocity will be high enough to pack the cylinders properly. On a daily driver, the RPM will not be passing enough CFM to keep velocity up for good cylinder packing and the motor might run worse than it did with the stock manifold, particularly at lower rpm's.
if you are not changing anything else, the performer is your better choice, not the rpm performer. Dual plane is a better choice for you.
Either manifold will work as they are both dual plane though Edelbrock claims a higher RPM band for the RPM version.
A 750cfm carb is WAY, WAY too big for a street driven car that sees little high rpm operation. The OEM 460 Ford ran a 500-525 cfm and got reasonable(??) gas mileage for the time. I tried a 780 Holley 3310-1 on my long gone '79 460 truck - gas mileage went from poor to abysmal and with the performance also going away.
Here's the industry accepted formula for determining carb cfm:
CID x RPM x V.E. / 3456 = CFM
428 x 3000 x .85 / 3456 = 315cfm
428 x 4000x.85 / 3456 = 421cfm
428 x 5000 x .85 / 3456 = 526cfm
428 x 6000 x .85 / 3456 = 631 cfm
Looks like I'd be considering a 600 to 650 max carb Which means at any of these RPM figures, you don't need that much carb. And with gas at $3.75/gallon,,,,\\\\\////???
I goofed, it was a performer I was looking at, not the RPM, and the reason I
was going with 750`s is thats whats sitting on my work bench.The car came
with a 750 originally and worked fine. PS the 428 is a Pontiac, not a Ford
Quote:
Originally Posted by redrodman48
Either brand, Ford or Pontiac, volumetric efficiency is, well volumetric efficiency in general terms the same - a 750 is too big. But, with that said - your car, your performance and your gas tank that needs to be filled - go with it:D
Well when it comes to summer drivers, Im not too worried about how much
fuel gets sucked up
Quote:
Originally Posted by redrodman48
Will you adopt me then? Until later this summer, I only have a 9-10 mpg pick up and I only eat a little:LOL: :LOL:
Sorry , I got that one covered too