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01-09-2010, 10:56 AM | #1 |
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BBC Intake
I thought I would start here to ask the question can I use a rectangular port intake on oval port heads with good results? I have seen somewhere in the past that people were doing this with great HP results. It was suppose to work better than the oval port intake. I thought maybe I can get some input on this.
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01-09-2010, 11:47 AM | #2 |
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Re: BBC Intake
I used to do it back when there were not a lot of really good oval port intake manifolds. It works, but I don't know that I'd say I ever got "great HP" results from it. These days, you can get a good oval port intake of just about any type, so I haven't even thought of doing it again in recent years.
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Alan Roehrich 212A G/S |
01-09-2010, 01:37 PM | #3 |
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Re: BBC Intake
Hey Jeff, I have heard of guys taking an oval port intake on rectangle port heads-- and open them up to some what match the heads. If you want to experiment, I have a dual plane oval port intake w/ 4500 opening. Also have the 4150 adapter. Let me know, I'll have to dig it out of the archives. Ed
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01-12-2010, 02:17 PM | #4 |
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Re: BBC Intake
Can you open the oval ports up enough to match the intake? I think a new manifold would work better. Sell the rectangle to recover the cost.
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01-12-2010, 06:51 PM | #5 |
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Re: BBC Intake
Never really known anyone who has done that, or would admit to it. Too great a mismatch as far as I am concerned. Oval intake on rectangular head far more popular.
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01-18-2010, 12:34 PM | #6 |
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Re: BBC Intake
ran my footbrake launched Chevelle with a cast iron oval port headed 468 for many years with both a rectangular Performer RPM Air Gap and Holley Strip Dominator intake.
Made at least 725HP@ 6300 and 600+ ft./lbs. torque @ 5100 RPM! Some say at least 750HP!! Ran 10.07 @ 131 through a full exhaust system in my nearly 3900 lb. Chevelle as well it ran quicker and faster than EVERY 454, 496, 502, GM's 720HP 572 and most 540's in a similar Chevelle here in Division 1 brackets! http://s381.photobucket.com/albums/o...current=10.flv Last edited by 1320racer; 01-18-2010 at 12:36 PM. |
01-18-2010, 12:49 PM | #7 |
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Re: BBC Intake
Years ago the boat industry was real good about putting GM dual plane square port intakes on the oval port heads. (large oval, not the peanut ports) Over the years I have had quite a few of those come through the shop. It might have been done to get away from the Q-Jet carb and go to a more efficent, for the application, square bore carb. I never tested the difference. I did change a few of the manifolds out. I was told by a couple of customers that it still ran the same top end, but had better throttle response with the round manifold.
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Adger Smith (Former SS) |
01-19-2010, 09:13 PM | #8 |
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Re: BBC Intake
The rect port intake maybe a good idea when oval port heads have been epoxy or welded while being ported. Raised runners.
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