I have the smaller version that came on '70-71 340 and 383 mopars. Primary bores are 1-7/16" and secondaries are 1-11/16". CFM? That's a good guestion. For every source that says it's 550cfm, you can find another one that says 450cfm. The 440's used one with 1-11/16" primary and secondary. Every source says it's 100cfm more than the small one even if they don't agree there.
I have the non-heated Clifford, but I bolted a plate on the bottom that I'm running the coolant through. I'm going to restrict the flow. The manifold is a lot hotter than I expected.
