1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Will a 13b header fit a 12a?

Thread Tools
 
Search this Thread
 
Old 06-19-10, 12:27 PM
  #1  
Rotary Lifer

Thread Starter
iTrader: (8)
 
roarinrotaryrx7's Avatar
 
Join Date: Jul 2004
Location: Windsor, Ontario
Posts: 524
Likes: 0
Received 0 Likes on 0 Posts
Will a 13b header fit a 12a?

Just curious if it would work, I found a thread about modifying a 12a header to fit a 13b but not the other way around.
Old 06-19-10, 02:26 PM
  #2  
Once a Marine.....
iTrader: (26)
 
patmac6075's Avatar
 
Join Date: Sep 2009
Location: MKE WI
Posts: 722
Likes: 0
Received 2 Likes on 2 Posts
Pretty sure it cannot.

In that thread they made the smaller 12a flange wider to fit the 13b.....going to be tough making a 13b flange narrower.
Old 06-19-10, 04:55 PM
  #3  
Lives on the Forum

iTrader: (5)
 
84stock's Avatar
 
Join Date: Apr 2003
Location: calgary
Posts: 5,537
Likes: 0
Received 9 Likes on 5 Posts
I have a roadrace 12a header
Old 06-19-10, 05:35 PM
  #4  
Old [Sch|F]ool

 
peejay's Avatar
 
Join Date: May 2001
Location: Cleveland, Ohio, USA
Posts: 12,506
Received 416 Likes on 296 Posts
It depends on the header.

A large diameter, thickwall tube header (Racing Beat) or a factory manifold can be ported and the mounting holes ovalled. It's time consuming but trivial.

A thin tube header won't be as easy, unless it has a very thick flange.
Old 06-19-10, 06:55 PM
  #5  
Needs More Noise

iTrader: (12)
 
bwaits's Avatar
 
Join Date: Nov 2001
Location: Georgia
Posts: 3,375
Likes: 0
Received 1 Like on 1 Post
Yes, it is pretty simple if it is a non-collected header. Cut the flange in the middle, remove 10mm. Cut the front tube about 1/2" away from the exit flange, remove 10mm from teh end of the tube and them weld it all together.

-billy
Old 06-20-10, 12:10 PM
  #6  
Rotary Lifer

Thread Starter
iTrader: (8)
 
roarinrotaryrx7's Avatar
 
Join Date: Jul 2004
Location: Windsor, Ontario
Posts: 524
Likes: 0
Received 0 Likes on 0 Posts
This is the one I'm looking at. Look like it might work? http://i72.photobucket.com/albums/i1...e/P5110333.jpg
Old 06-20-10, 12:16 PM
  #7  
Lives on the Forum

iTrader: (5)
 
84stock's Avatar
 
Join Date: Apr 2003
Location: calgary
Posts: 5,537
Likes: 0
Received 9 Likes on 5 Posts
yuck
Old 06-20-10, 12:48 PM
  #8  
Rotary Lifer

Thread Starter
iTrader: (8)
 
roarinrotaryrx7's Avatar
 
Join Date: Jul 2004
Location: Windsor, Ontario
Posts: 524
Likes: 0
Received 0 Likes on 0 Posts
How much for your 12a header then?
Old 06-20-10, 02:41 PM
  #9  
Old [Sch|F]ool

 
peejay's Avatar
 
Join Date: May 2001
Location: Cleveland, Ohio, USA
Posts: 12,506
Received 416 Likes on 296 Posts
Originally Posted by bwaits_
Yes, it is pretty simple if it is a non-collected header. Cut the flange in the middle, remove 10mm. Cut the front tube about 1/2" away from the exit flange, remove 10mm from teh end of the tube and them weld it all together.

-billy
That is, again, waaaaay lots of work.

It's only 5mm of mismatch per port. That is less than 1/4". Most headers have almost that much port step-out to begin with, so it is trivial to open the inside (or outside) as necessary to ensure no improper mismatch. Slotting the holes poses no great risk to strength, either.

I really wish I could find the link, but it was really old and is probably gone by now, but there was an Australian site where they detailed how to turbocharge a 12A, using 13BT exhaust manifolds and a spacer so the turbo could clear the 12A intake manifold.
Old 06-20-10, 06:44 PM
  #10  
Needs More Noise

iTrader: (12)
 
bwaits's Avatar
 
Join Date: Nov 2001
Location: Georgia
Posts: 3,375
Likes: 0
Received 1 Like on 1 Post
Yes peejay, we all understand your preferred method. Some of us prefer to handle it differently.

-billy



Originally Posted by peejay
That is, again, waaaaay lots of work.

It's only 5mm of mismatch per port. That is less than 1/4". Most headers have almost that much port step-out to begin with, so it is trivial to open the inside (or outside) as necessary to ensure no improper mismatch. Slotting the holes poses no great risk to strength, either.

I really wish I could find the link, but it was really old and is probably gone by now, but there was an Australian site where they detailed how to turbocharge a 12A, using 13BT exhaust manifolds and a spacer so the turbo could clear the 12A intake manifold.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Josh83rx7
1st Generation Specific (1979-1985)
7
09-02-15 05:57 PM
Inspector71
1st Generation Specific (1979-1985)
9
08-26-15 12:06 PM



Quick Reply: Will a 13b header fit a 12a?



All times are GMT -5. The time now is 06:52 PM.