15.0 mpg to 21.6 mpg!

IMO the title is OK. Its an attention getting headline and this forum is a part of the new media anything. I've seen and heard much worse leads, and don't mean the NY Post alien baby stories. :razz:

You'll know its cruising too lean when the engine starts surging. Also you'll have to find by experimentation when the cruising is more on the main circuit than the idle. Don't be surprised if its above 50 mph. For reference, on my setup with Holleys its been above 60 mph. The Carter/Eddy may be lower.

As far as this being better than the Eddy 750 goes, that's not surprising based on what Tuner and others have observed. There's been some manufacturing differences from the Carters that can create some odd fueling. This one always stuck in my head.

The 1407 750 CFM uses the same casting for the primary cluster as the 625 CFM carbs in spite of the fact the venturi minor diameter is 5/16” or so lower in the 750 body. This places the exit of the booster venturi that much above the “vena contracta” in the air flow, the result is the “booster signal” is not obtained in the correct location and the metering is erratic, the A/F wanders rich and lean as load and RPM vary as the throttle position is changed.

Click to expand...

Of course it can be fixed as can all the other anomolies. Its just not what most of us expected when we first went out and bought an aftermarket carb.
:lol:
More from where that quote came from in the first two pages here
Edelbrock 1407 - Speed Talk