12-25-2020, 01:52 PM
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CC Member
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Join Date: Jul 2003
Cobra Make, Engine: Unique Motorcars 289 USRRC, 1964 289 stroked to 331, toploader
Posts: 1,129
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Quote:
Originally Posted by blykins
A well ported 289 head will flow about 200-220 cfm, depending on the casting, while keeping the port volume in check. We convert them to 7mm or 5/16" valve stem size. That supports 450 hp easily.
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Quote:
Originally Posted by blykins
I wouldn't be concerned about the port wall thickness, I'd be concerned about the port volume. A hogged out port, even if it flows a lot, would make for a slugglish 289 on the street. On the race course, it would take a bit of rpm to make it efficient.
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Do you send those heads out or do the porting in house, Brent? Are we talking about the same porting in both of your quotes above? In other words, if you port for the top quote, do you end up with the bottom quote, or can you have good street performance with the top quote? Reading between the lines, I think the latter good street performance, but just checking.
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Paul
Unique Motorcars 289 USRRC
1964 289 5-bolt block
Toploader and 3.31 rear
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