Holley 4 Barrel on a 275 Cubic Inch Flathead

[40larry]

Does anyone have any first hand experience using a Holley 4 Barrel on a 275 cubic inch flathead? I have an Offenhauser 4 barrel intake and looking at both 600 CFM and 350CFM carbs. These are new carbs for general purpose applications sold by Holley. Thanks

40larry

[JayChicago]

You typed 350 cfm. Did you mean Holley 390 cfm?

I have the 390 on a built flathead with a fat cam. Works well. I would think 600 cfm would be over carbureted.

There is a recent long thread titled “4 bbl carb on flathead?” Lots of info and first hand experience there.

[deuce_roadster]

Hi Larry, I have a 390 on an offy intake. I mounted the carb backwards to make the throttle linkage easier. I had to also put an adapter to raise the carb up due to the center water outlets on my 59 series engine heads.
Mike

[tubman]

I had a 390 Holley on an Offy 4BBL manifold (using an adapter) on an 276 ci 8BA with an Isky MAX-1 in a '36 3-window about 30 years ago; it was the first hi-performance flathead that I built. It ran fine, but it wasn't a "world-beater". I don't think this had anything to do with those components. More than likely, it was due to my lack of flathead knowledge on combustion chamber dynamics and ignition systems. I'd like to do it over again these days, but I am too committed to using earlier components.

[nelson2]

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a 500 cfm edelbrock works well and is plenty of cfm. also depends on what cam and porting you have.