I ran a 500 CFM Carter AFB on a Super Six intake on the otherwise stock 225 in my 76 D100 and it worked well. The secondaries were operational, but I don't think it moved enough air to open up the air door over the secondaries. The primaries are just about the same size as the throttle bores on a BBD. I want to try it again with the secondaries disabled and see how it does.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

I have run the 500 and the 600 Edelbrock on stock to nearly stock engines without any trouble. I never unhooked any of the secondaries because they never come into play anyway. Like you said it takes a certain amount of air flow to open the secondary air door. And a stock slant 6 will be pushing it to get any kind of use out of the secondaries. Not saying you can't get them to open up, just that it will likely run just as well off the front two.

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6