Manifolds/Heads - Team Camaro Tech
Tech 2000 Our previous General Forum
Replies ONLY - no new topics.

 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old Mar 11th, 00, 10:24 AM Thread Starter
 
Join Date: Jan 2000
Location: Indianapolis
Posts: 17
Post

I,m aware of the differences between oval port & rectangular port B.B.C. heads but, are the bolt patterns the same &, in a pinch, could you put a rectangular port manifold on an oval port head ??, is the port alignment close enough ??. Thanks, Mike.
Mike Anderson is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old Mar 11th, 00, 11:18 AM
Senior Tech
 
Join Date: Dec 1999
Location: Big D little a-l-l-a-s
Posts: 523
Post

Yep,

The bolt patterns are the same. You didn't say which manifold you will be using but for example, if you were to use a Edelbrock manifold, you would want to use the Edekbrock RPM manifold and NOT the EDELBROCK RPM PERFORMER manifold because the port size is SMALLER on the RPM model and it would at least match up somewhat better with the smaller ports on the heads. In either case make sure you use the manifold gasket that goes with the manifold you will be using and NOT a manifold gasket based on the heads you are using.

By the way, dual plane manifolds like these are much more forgiving than their single plane counterparts when it comes to mismatched port sizes.

Peace,

Mike didn't ask which ones would be better!!! I'm sure he is aware that it would be better to match the port size of the manifold to the heads, but he COULD use a small rectangular port manifold like the Performer on oval port heads if that is all he has to work with. Performance would not suffer that much with this combination compared to the ideal setup.

Peace,

NO it is not OK,

I am fortunate because I can afford the to buy whatever components are necessary to build the "PERFECT" setup. I then DYNO test the combination and I change the combination to one that works better according my DYNO testing. So basically I KNOW what works and what doesn't work and I can prove it. The surprizing thing about this is that you can effectively use mismatched components and get surprizing results. Not as good as using matched components mind you but still acceptable in most cases.

The whole point of this is that you HAVE to use less than ideal parts combinations because of cost considerations or parts availability, you can still get accepatble results. The reason I try to contribute to this site is that I have fun sharing my experiences with others and hope that they can learn from my mistakes and experiences.
Whether they choose to or not however is totally their choice as it is also yours.

END OF SERMON



[This message has been edited by sr71bb (edited 03-12-2000).]
sr71bb is offline  
post #3 of 11 (permalink) Old Mar 11th, 00, 05:46 PM
Tech Team
 
Join Date: Jan 2000
Location: Whitehouse, Texas, USA
Posts: 84
Post

You can bolt a square port manifold on oval port heads, and the car will run, but it wont run very well. An oval port intake should always be used with oval port heads. Oval port heads are made for low to mid range torque. They have smaller ports for higher air velocity. (Air moves faster through the smaller opening). The large square port intake would slow the intake charge down. Also, the incoming air/fuel from the large manifold ports would hit the sides of the smaller head intake ports, and create all sorts of turbulence. Anyone who has ported heads will tell you that the intake to head ports should be "matched" for best airflow. The large port intakes belong on large port, big displacement, high rpm, high compression head engines. Thats the way Chevy designed them.
Peace69/Z28
69Z/28, 70 Chevelle SS, 90 454 SS p.u.
Peace69Z/28 is offline  
 
post #4 of 11 (permalink) Old Mar 12th, 00, 09:21 AM
Tech Team
 
Join Date: Jan 2000
Location: Whitehouse, Texas, USA
Posts: 84
Post

sr,
Mike didn't mention what brand of manifold he was asking about. I think he was referring to Chevy GM manifolds and heads. I can't imagine anyone wanting to put a GM square port intake manifold on GM oval port heads, unless you want the car to run like "crap". Ok?
Peace69/Z28
Peace69Z/28 is offline  
post #5 of 11 (permalink) Old Mar 12th, 00, 07:59 PM
Tech Team
 
Join Date: Jan 2000
Location: Whitehouse, Texas, USA
Posts: 84
Post

sr,
Relax, relax. You must think I'm "knocking" your reply. I'm NOT. When I seen this question posted, and typed in my response, I didn't see yours there. You simply "beat" me to it. Now youre beating "me". I totaly respect your response, and I am glad you are sharing your FRIENDLY, fun experiences with us. Peace69/Z28
Peace69Z/28 is offline  
post #6 of 11 (permalink) Old Mar 13th, 00, 05:19 AM
Senior Tech
 
Join Date: Dec 1999
Location: Big D little a-l-l-a-s
Posts: 523
Post

Peace,

I apologize. In looking back at my responses, I didn't mean to attack your response. My biggest pet peeve is manfacturers getting away with false advertising and I consider a personal crusade to expose those claims as false and to further support those manufacterers that DO have great products. I get too aggressive sometimes and I guess that came out here. Your responses to Mike's questions were entirely accurate and hopefully helpful not only to him but others and that my friend, is what it is all about!!!



[This message has been edited by sr71bb (edited 03-13-2000).]
sr71bb is offline  
post #7 of 11 (permalink) Old Mar 13th, 00, 07:14 AM
Tech Team
 
Join Date: Jan 2000
Location: Whitehouse, Texas, USA
Posts: 84
Post

sr,
Hey, no problem. I totaly agree! I,m here to help, to learn, and to have fun. Heck, us ole east Texas boys love them thir ca-mar-roes. Thanks.
Peace 69Z/28
Peace69Z/28 is offline  
post #8 of 11 (permalink) Old Mar 13th, 00, 08:45 PM
 
Join Date: Feb 2000
Location: Fairfield,CA
Posts: 20
Cool

Mike,
The intakes will bolt up no problem. The bolt pattern on the heads is the same. You would not want to run a square port intake on an oval port head under any circumstance. The turbulance caused from the intake charge hitting the smaller intake port would make the engine run very poorly. You can run an oval port intake on a square port head in a pinch til you can find the right intake. The smaller port on the oval port intake would not be a disruption of the intake flow only the volume of the air would not match the capability of the rectangle port head. Also if you are looking for a used oval port intake be aware that there are different sized oval port openings. The later model heads have a relatively small opening compared to the older ovla port heads and the same intake theory from above would apply there as well. I hope this made a little sense..
her69 is offline  
post #9 of 11 (permalink) Old Mar 14th, 00, 12:34 AM
Senior Tech
Bruce
 
Join Date: Jan 2000
Location: PA
Posts: 921
Question

here's a question for you then? i agree, oval with oval and square with square is what you want, but why does, i believe it was dart or brodix, leaning towards dart, claims that in one of there add's, for there intake, to run a mis-match in ports? i believe they said to run oval port intake with square port heads with there intake? this has always been a question to me, and i still can't figure it out...
this quote was in a summit or jegs catalog.
later,
bruce
bruce69camaro is offline  
post #10 of 11 (permalink) Old Mar 14th, 00, 07:06 AM
 
Join Date: Feb 2000
Location: Fairfield,CA
Posts: 20
Cool

The theory behind running an oval port intake on a square port head is to increase the velocity of the intake charge(measured as FPS)and the optimum number being somewhere from 670-720 FPS. The larger intake port opening on the sqaure port will lower that number due to the volume of air it must move. The square port head has a velocity problem particularly at lower RPM levels. By using the smaller opening on an oval port intake you can effectively increase the velocity of the intake charge and get closer to the ideal FPS numbers. This will more effectively fill the cylinders at lower RPM's than the square port intake. Making the engine more responsive at low RPM. This used to be used by Circle Track guys way back when they ran big blocks. It may be on its way back or at least a little closer to the mainstream. It is a way to make a Square Port more responsive on the street. But in my opinion if you are building a street motor it is better to use the oval port in the first place. The key to making a good street engine is to keep the velocity up and to not allow for puddling of fuel caused by ports that are to large. This is a case where bigger is not better. You can make some big HP and Torque numbers with an oval port engine and it is more suited to the lower Rpm's associated with street conditions. Hope this makes sense I did not want to get to technical trying to keep it as simple as possible for everyones benefit.
her69 is offline  
post #11 of 11 (permalink) Old Mar 14th, 00, 08:12 AM
Senior Tech
Bruce
 
Join Date: Jan 2000
Location: PA
Posts: 921
Thumbs up

thanks for explaining it, seriously. i never understood what they meant by that quotation.

bruce
bruce69camaro is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome