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Buick Nailhead cfm

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Schurkey:
Take a look on Buick web sites, and they're quite certain that any Buick engine--Nailhead, small-block, or big-block will magically need way more CFM than a comparable Chevy.

There is a way to explain that:  Restrictive intake porting.  Crappy manifolds, and tiny cylinder head intake ports respond to larger-than-expected carbs.  A Chevy 396 with "small" intake valves uses a fairly huge port, and a 2.07 intake valve.  A Nailhead 401 had a goofy intake port, small and curved; with a tiny intake valve--under 2" if I remember correctly.  Even the Buick Big-Block has (almost) Chevy Small-block sized intake valves.  Takes a "Stage 1" cylinder head to get a 2.12 intake valve, and the port size is still the same as with the tiny "typical" valve.

Yep, that's one of the many attributes of the Q-Jet:  Can be tuned to work on anything from Pontiac 6-poppers to Cadillac 500, and most anything in-between.  Including Ford 385-series Big Blocks.

55super56R:
Keep in mind that Crappy is in the eye of the beholder!!  The great thing with long restricted intake runners on large displacement engines like a Nailhead is that they result in very high intake air velocities and great low end torque.  That's also the reason Nailheads like bigger CFM carbs - high intake velocities result in more efficient venturi operation and response.  A large venturi does not function properly with low air flow velocity because the pressure differential between the venturi bore and the fuel bowl is not high enough to lift the fuel from the bowl to the venturi port. 

For a street engine in a heavy car there is no substitute for stump pulling torque.  The 401 and 425 Nailhead delivers the torque and great throttle response with mild mods because of the intake manifold, long head runners, and intake valve/port geometry. 

The biggest mistake most of the Chevy small block crowd makes is too much CFM (oversize venturi size) for the application.  It's fun to brag about the shiny 750 or 850 CFM lump on top of the intake manifold with the hood up but the doggy low end response really sucks.

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