Confused about oval port vs. Rectangular port heads

donsz

Well Known Member
I'm installing CPP power steering in my 1957 Chevy NAPCO truck, it has a 1965 348 engine. Naturally the left header clearance
needs to be resolved. I saw some headers: Patriot Exhaust Tight Tuck Headers Chevy 348-409 (Oval Ports), that seem to
have a design that lends it self to modification for the is application. The thing is, from what I can see, I appear to have rectangular port
heads. The heads are the heads that came with the engine, which I'm pretty sure was never modified. The reason I'm confused is that
my research says:"Oval-port heads are capable of flowing enough air to support around 600-650 horsepower in stock form.
Rectangular-port heads (bottom), should be reserved for engines that spend much of their time at high engine rpm."


This engine did come from a big truck, so I'm guessing high rpm wasn't what this engine was about. My question: what type
head should a stock 1965 349 truck engine have? Thanks
don
 

427John

Well Known Member
That Jeg's description is quite confusing,since 348-409s all use the same exhaust pattern whether their small or big port heads.BBC's also have the same exhaust port pattern whether their oval port or rec port heads and I've never seen BBC headers described as oval port or rec port they're all the same as far as the flange shape goes.I have seen some round port flanges for use with uncommon factory heads (2nd design L88/ZL1)and possibly some aftermarket heads but that stuff was usually open chassis race type pieces.On top of that their picture of the parts clearly shows the gaskets being for the square shaped 348-409 exhaust ports WTF.
 
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