Why does Edelbrock and Barry Grant rate their carburetors to cam duration @.05 and what does it mean if you run a cam with duration of
.224/.230 and the carb. is rated for only up to .220? Do you really need a carb. rated for that duration and above? Thanks,

It would be real handy if you would explain what you are referring to. I was not aware that any carb was "rated" by cam duration.

There IS a difference in how carbs are "flowed" however. Holley commonly rates 4bbl carbs at 1.5" vacuum, but rates their 2bbl carbs at 3".

What this means, example, is that the infamous 500cfm Holley 2bbl doesn't flow 500!!! at all when compared to a 4bbl rating. It's down in the 37x cfm range.

Maybe I should try and Re-clarify this. I really shouldn't say they rate their carbs. so to speak, they just include it in their catalog carb. description. If you look thru Edelbrock catalog, the carb. discription for say the AVS650 is good for cams rated to .220 dur. @ .05.

I sure don't know. Here's a screenshot out of their online catalog

Okay, Thanks guys. Looks like they removed it from their description, now I don't have to worry about that anymore! I know I am not loosing my mind! I have seen it way too many times before.

Demon rated their carbs by cam duration.

""A Speed Demon™ carburetor is ideal for muscle cars, stock rebuilds, tow trucks, mild performance applications and crate motors. They are designed for engines with cam profiles between 220 and 240 degrees duration at 0.050".""

""he Road Demon Jr promises to be the ideal carburetor for budget-conscious enthusiasts needing a carburetor for performance upgrades for stock to mild performance levels. Its designed for small block V8 engines with cam profiles from less than 220 degrees duration at 0.050".""