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Old 05-23-2003, 12:36 PM
396 396 is offline
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Post big block chevy

i have a 396 with oval port closed chamber heads. is there any beneifts changing to a rectangler port open chamber head? Are there any down falls
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Old 05-23-2003, 03:56 PM
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it depends on the use of the car, rectangle port heads make horsepower from 5500 rpm up. Oval port heads have plenty of port area for a mild street car, I have seen some serious oval port drag cars also. If you are going to do a daily driver do the oval ports, if you are a serious drag or saturday night special use the rectangle . Speed costs money how fast do you want to go!
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Old 05-23-2003, 04:45 PM
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oval ports are called "peanut ports" and were mostly used on pickups with the theory that they produced more torque but do not flow as well. I have a brand new still in the box set of peanut ports but the machine shop that bored my engine advised me to rebuild the set of rectangle heads I had since they felt rectangle heads are much more appropriate on a hot rod engine.
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Old 05-23-2003, 05:06 PM
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I agree with Bobcrman, I use the oval ports on the street ,more power with higher gears.
I use sq.ports with low gears, power is at higher rpm.
It all depends on where you want the power band.
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Old 05-23-2003, 05:10 PM
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Oh yeh on sq. ports you need to use a bigger carb. and large pipe headers. The whole idea is more air,better breathing. Good Luck
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Old 05-23-2003, 07:21 PM
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big block chevys have 3 types of intake ports on the cylinder heads. 1st type is peanut port which is really small. the 2nd is the large oval port which is very popular on many street cars and can be used for racing if u have the correct castings. the oval ports are good till 6500 RPM's. After 6500 RPMs the rectangle ports are your best bet. I've been studying big chevy for years especially when it comes to the street/strip area and if its not going to be used over 6500 RPMs go with the oval ports made from 1971- 1974. and if your budget allows get some stainless steel valves and install over size valves. do some port work and clean up the bowl area and you'll be impressed.
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