BBC Intake

J Kuchel · 01-09-2010, 10:56 AM

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.

Alan Roehrich · 01-09-2010, 11:47 AM

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.

BCRACING7469 · 01-09-2010, 01:37 PM

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

Harry 6674 · 01-12-2010, 02:17 PM

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.

Tim H · 01-12-2010, 06:51 PM

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.

1320racer · 01-18-2010, 12:34 PM

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

Adger Smith · 01-18-2010, 12:49 PM

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.

blasttime · 01-19-2010, 09:13 PM

The rect port intake maybe a good idea when oval port heads have been epoxy or welded while being ported. Raised runners.

01-09-2010, 10:56 AM	#1
J Kuchel Banned Join Date: Apr 2005 Location: Sterling,Illinois Posts: 111 Likes: 0 Liked 0 Times in 0 Posts	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.

01-09-2010, 11:47 AM	#2
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,090 Likes: 1,534 Liked 1,758 Times in 398 Posts	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. __________________ Alan Roehrich 212A G/S

01-09-2010, 01:37 PM	#3
BCRACING7469 Junior Member Join Date: Aug 2007 Location: West Michigan Posts: 12 Likes: 0 Liked 0 Times in 0 Posts	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

01-12-2010, 02:17 PM	#4
Harry 6674 Senior Member Join Date: Dec 2006 Posts: 589 Likes: 0 Liked 0 Times in 0 Posts	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.

01-12-2010, 06:51 PM	#5
Tim H VIP Member Join Date: Jan 2007 Posts: 1,039 Likes: 1,062 Liked 481 Times in 158 Posts	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.

01-18-2010, 12:34 PM	#6
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 2,628 Likes: 160 Liked 759 Times in 379 Posts	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
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	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. __________________ Adger Smith (Former SS)

01-19-2010, 09:13 PM	#8
blasttime Junior Member Join Date: Feb 2009 Posts: 43 Likes: 0 Liked 0 Times in 0 Posts	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.