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FE Technical Forum / Re: big ,med, or small block
« on: November 25, 2023, 04:20:45 PM »
The reason a 390GT can't run with a 396/375 is obvious when you look at the flow comparisons. The 390FE heads of the era only flowed in the 235-240cfm with the 406-427 heads flowing 250-260cfm. The best FE MR heads only flowed ~280cfm in 1966/67. Any 396 head would flow 290-310cfm and the hp heads flowed 320-330cfm. A 396 aluminum intake manifold would flow 390-410cfm, where the C6/7-F/H intakes would only flow ~285-290cfm, with the sidewinder J averaging 305cfm. I just within the last 3 months flowed 4 sets of 396 Stock Eliminator heads and 3 unported intake manifolds for a local racer who went to INDY this year. His heads flowed 320-330cfm and the intakes flowed 409-420 cfm average. The best SS FE heads I have had on my flow bench only flowed 305-320 cfm. The 428CJ heads only flow 260ish cfm and they would keep up with the 396SS in pure stock trim. The 427HR heads as cast flowed 285-290cfm, and the 8V intake manifold would flow 365cfm as cast and they were used in lightweight cars to make them competitive. All these FE heads could be improved by 10-15% but that is still not on par with the BBC if we are honest about them. Joe-JDC