What the title says. I've got an HO 305, with Trick Flow's Super 23 heads (supposedly 242cfm ideal flow), A mild cam, edelbrock intake, and Heddman 68470 headers. I'm wondering what, if anything, I need to do to this new carburetor to make it work properly with this setup. Let me know if I missed any needed information.

 

Return it and get a SMI or Cliff Ruggles built Q-Jet.

 

Okay... first of all, I can't. Second, why? I understand everyone loves Q-jets and Q-jets are great blah blah whatever. I got an Edelbrock because they're easy as hell to tune.

 

So are the Quadrajets. The Edelbrock or shiny box wastes gas and does not have the ability to be fine tuned as well as the Q-Jet. The later non computer Q-Jets can even have their crusing air/fuel ratio dialed in on a running engine via the APT screw. I lost nearly 30 ft/lbs of torque with an Edelbrock 600 cfm at 2,500 rpm on a mild 305, not to mention about 2-3 mpg. No amount of tuning fixed it. After running it for about 6 months, rebuilt the quadrajet and all my low-end power and mileage came right back. I was running an edelbrock performer rpm at the time. With the Quadrajet it just went, the Edelbrock always had a WOT bog coming off the line. On 1 quart of gasoline my most recent quadrajet ran 1 minute longer on the same fuel on a very healthy 383 at a steady 2,000 rpm.

 

Not my fave but you already have it so yea, it should work great with your built 305.
If you can come across a quadrajet they are nice, myself i prefer a Holley DP.

 

Edelbrock 650 cfm is not too big for your 305. The quadrajet can actually flow 850 cfm, but is designed to flow only as much as the engine needs. A 305 is never going to consume 850 cfm - your 650 is right in the ballpark.

BUT, like Fast355 said above, depending upon how big your camshaft is, the resultant vacuum being pulled through the carb might not be sufficient for the Edelbrock carb to function properly at all rpms and engine loads. Larger duration camshafts produce less vacuum. So if you have that WOT bog coming off the line, then no amount of tuning to that Edelbrock will make the bog go away.

 

I tried both a 500 cfm and 600 cfm Edelbrock on my 305 Vortec in my Corvette. The 500 cfm had quicker times and was much more responsive. That 305 was in the 340-350 hp range.