Just purchased a 2x4 bbl iron mopar manifold for the poly 318. What are the recomended carbs for this set with  mildly ported heads, headders, cam to be determined , mated to a 727 tqflite all in a 64 Polara 500. This is a show and go daily driver.  

there's an equation for figuring out CFM rates to get you in the ballpark. C.I.D. x MAX RPM / 3456

C.I.D. being cubic inch displacement.

MAX RPM being where your motor peaks in power.

3456 is just a constant for figuring out the equation.

It is somwhat accurate and depening on your pleasure you can either round up or down to the closest available flow rated carb.

EX:

340 x 5500 / 3456 = 541.087

Which means you can either run a 600 or a 650. This is not 100% accurate, it's just an exquation i learned in trade school and should get you close. One other thing i learned was that sometimes in from the factory the carbs were actually a little to big for their applications. But this is only a ballpark figure to get you close. It'll take lots of tuning to get it the way you want and maybe you wont even end up using a carb with a flow rate anywhere close to what you get out of thsi equation.

They ran Carters originally. These days, most folks will run the Edelbrock carbs (made from molds bought from Carter before they went out of business).

You may find these links helpful...

The Polyspherical Engine association (there's a list of places to find parts & info):
http://www.geocities.com/polyman64/

At the top of that page you'll find the following links.

The 318 Poly Yahoo Group (which is where we all are (ask us ANYTHING):
http://autos.groups.yahoo.com/group/318poly/

And the Poly Forum, where we'll all lurkers, and casual posters:
http://www.diamondbackengines.com/forums/index.php/board,6.0.html

More info at the sites above...

~Jason