Edelbrock RPM Air Gap quality - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-08-2006, 06:52 PM
Registered User
 
Join Date: Nov 2004
Location: California
Age: 67
Posts: 828
Wiki Edits: 0

Thanks: 27
Thanked 21 Times in 19 Posts
Edelbrock RPM Air Gap quality

Hi guys.

I thought these were supposed to be as-cast to closely match a FelPro 1205 Intake gasket (SBC application). After checking my gaskets vs AFR heads, and the gaskets vs the Eddy Air Gap, it looks like the Air Gap needs up to .12 removed from the port walls to match. Any similar experiences?? Did you port match?? Port matching seems problematic becases the port isn't nicly tapered all the way to the cylinder head joint. It looks like hours of work to avoid a converging/diverging/converging port after grinding.

Pat

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-08-2006, 07:04 PM
NAIRB's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2002
Location: cimarron, ks
Posts: 1,658
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Pat,

If the intake opening is slightly smaller than the cylinder head, you have no problem.

As a matter of fact, there will be no noticeable power decrease. You just don't want any areas of the head protruding into the path of the incoming air fuel charge from the intake aperature.

Are the intake's port openings fairly straight and uniform, just smaller?

I've had some of the professional products stuff and they are horridly crooked.


Brian
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-08-2006, 07:40 PM
Registered User
 
Join Date: Nov 2004
Location: California
Age: 67
Posts: 828
Wiki Edits: 0

Thanks: 27
Thanked 21 Times in 19 Posts
They're a little misaligned, as well as undersize. I was pleased to note that there is no place that the intake port would overlap the head, but .125 is a LOT of mismatch, doncha' think? It has to impact performace. If you reduce the port area by 7-10%, it seems to me you are limiting flow capacity. Correct??

Pat
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-08-2006, 08:23 PM
NAIRB's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2002
Location: cimarron, ks
Posts: 1,658
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
You would be surprised to know that the real answer to that would be not quite as much as you would think.

Just don't assume that your intake openings need to be as large as the gasket. That's always a mistake, and the areas of port cross sectional areas where the intake runners meet the cylinder head are usually straight and high flowing.

This is the first area where novice head porters want to grind on, but in reality, these areas net little gain in terms of increased airflow.

The bowl areas, and any area with a turn in it and the valve seat are ultimately the limiting areas in terms of airflow. A port can only flow as much area as it's most restrictive portion of the port. The intake aperature ain't it most of the time.


Brian
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-08-2006, 09:02 PM
camaroman7d's Avatar
Member
 
Last photo:
Join Date: Dec 2003
Location: Vacaville, California
Age: 47
Posts: 2,245
Wiki Edits: 0

Thanks: 3
Thanked 9 Times in 9 Posts
Brian is steering you in the right direction. It is not always the "size" of the port that matters. Velocity matters as well. You won't hurt anything by port matching the intake, you won't see huge gains either (if any). Personally on performance builds I like to port match, that's just because I can't help it.

Edit: You have to remember this intake will be used on everything from bone stock heads to large runner heads. If they made the port fit the large heads, what would they do for the stock heads?

Royce
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-08-2006, 11:03 PM
Member
 
Join Date: Dec 2004
Location: Madison, WI
Posts: 1,885
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
You have no issues. Bolt it on.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-09-2006, 05:40 AM
Hotrodders.com Moderator
 

Last journal entry: PICTURE TEST
Last photo:
Join Date: Jan 2004
Location: york pa
Age: 52
Posts: 2,795
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
intake

Remember felpro makes gaskets, they don't design intake runners......

Porting to a gasket always cracks me up....

You will see zero difference,,,, Try this assemble the engine, go race the crap out of it untill you know for sure what times it runs, then come back port the intake to match the gasket and go race the crap out of it again... I got a dollar that says zero difference....

Keith
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-09-2006, 07:31 AM
engineczar's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2002
Location: In Flowbench nirvana
Age: 52
Posts: 1,630
Wiki Edits: 0

Thanks: 5
Thanked 43 Times in 40 Posts
Another thing that people do in error is that they match the heads to the gasket, and then the intake to the gasket. Then just bolt it on thinking that they've matched everything when in reality they don't take into account how the manifold fits the engine between the heads as assembled and torqued down. So instead of having the air/fuel flow with an unobstructed flow to the valve they actually now introduce overlaps between the manifold and heads. You're just better off with the intake smaller to take into account all the variables when it's assembled.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-09-2006, 09:49 AM
johnsongrass1's Avatar
Race it, Don't rice it!
 
Last photo:
Join Date: Jul 2002
Location: Columbia, Mo
Age: 37
Posts: 4,078
Wiki Edits: 0

Thanks: 0
Thanked 9 Times in 9 Posts
Sometimes that edge creates a fuel sheering piont that can reintroduce the fuel into the air stream.

Your mileage might vary .1 per gallon.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-24-2006, 10:26 AM
Duke of Cruel's Avatar
Car nerd
 
Last photo:
Join Date: Jul 2006
Location: sweden
Age: 40
Posts: 53
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by PatM
Hi guys.

I thought these were supposed to be as-cast to closely match a FelPro 1205 Intake gasket (SBC application). After checking my gaskets vs AFR heads, and the gaskets vs the Eddy Air Gap, it looks like the Air Gap needs up to .12 removed from the port walls to match. Any similar experiences?? Did you port match?? Port matching seems problematic becases the port isn't nicly tapered all the way to the cylinder head joint. It looks like hours of work to avoid a converging/diverging/converging port after grinding.

Pat

Its because the manifold also should fit smaller runner applications.
DoC
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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 for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Edelbrock Air valve?? voodoosurfer Engine 5 12-10-2013 10:16 PM
GN Votec verses Edelbrock RPM Sky65 Engine 16 11-26-2005 11:18 PM
351 windsor running rich ???? ve3ham Engine 19 08-08-2005 12:48 PM
Edelbrock RPM vs. old LT-1, Corvette manifolds 59vette Engine 1 01-24-2005 05:16 PM
Air Gap vs. Weiand, Performer/RPM, Holley, etc. (again!) acr Engine 10 12-05-2004 06:50 PM


All times are GMT -6. The time now is 07:31 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.