Here ya go-  from the old forum:

http://members.boardhost.com/MustangSteve/msg/1364323687.html

I just helped Bullet Bob fix his.  The valance is not too narrow, it just has too much bow in it.  Take out the bow and it will magically get wider.  The way to do that is to increase the angle of the offset right below where the valance screws on to the taillight panel behind the bumper.  If yuo exagerate that lower bend, about 6" from the bottom, it will make the valance fit straighter across the bottom and will then reach from side to side.  At that point the attaching pieces will also fit.  This comes up so often, I need to do an FAQ page on it.
 

same issue. I solved with NOS piece. I also have seen some people add some metal to each side and grind to shape.

Fyi, I have another NOS non GT panel for 67-68 for sale.

MustangSteve wrote:

I just helped Bullet Bob fix his.  The valance is not too narrow, it just has too much bow in it.  Take out the bow and it will magically get wider.  The way to do that is to increase the angle of the offset right below where the valance screws on to the taillight panel behind the bumper.  If yuo exagerate that lower bend, about 6" from the bottom, it will make the valance fit straighter across the bottom and will then reach from side to side.  At that point the attaching pieces will also fit.  This comes up so often, I need to do an FAQ page on it.
 

Makes perfect sense, thank you!

I picked up a NOS one from Carlisle years ago when I switched to duals but still had to build up the mating ends with  lead to get it to fit properly.
 I could have used a MIG but old school lead seemed to be an easier solution at the time.


 

Last edited by Rudi (1/21/2016 9:41 AM)

MS wrote:

I just helped Bullet Bob fix his.  The valance is not too narrow, it just has too much bow in it.  Take out the bow and it will magically get wider.  The way to do that is to increase the angle of the offset right below where the valance screws on to the taillight panel behind the bumper.  If yuo exagerate that lower bend, about 6" from the bottom, it will make the valance fit straighter across the bottom and will then reach from side to side.  At that point the attaching pieces will also fit.  This comes up so often, I need to do an FAQ page on it.
 

MS were you able to post a FAQ page on this?  I couldn't follow how you said to rework it to fit.  I don't follow the " increase the angle of the offset" statement.  Thanks Jerry

True74yamaha wrote:

Why can't you simply cut a slice out stretch to where it needs to be then simply weld a piece in?

You can, and some have. However, it's not as simple as leaving the valance in one piece and making the bow in it into a larger radius. No cutting, no welding, no body work.
 

Like True74YH said, you bend the mounting flange, across the top of the valance, so the valance is forced to fit tighter against the back of the car.  By bending that flange, it forces the valance to flatten out into more of a straighter line instead of a long arc at the bottom. This makes the valance wider and it will then fit like it is supposed to.  Once I get my 68 home, I will install a new valance on it and post in the TIP & HOW TO forum, but that may be a while.

Trying to simplify my explanation...
If you held the valance up to the back of the car, in the orientation it would be installed, take the flange at the top and bend that flange so the top of it points more to the front.  Bend it so the angle is exaggerated from what you think it will be when installed, but don't get carried away.  Then when you tighten all the screws at the top, it will force the bottom of the valance to fit correctly.  No bodywork is required.  Be sure you have the correct mounting studs that attach the bottom corners to the car, along with their little clips that hold the studs to the valance.  Sometimes a little percussion engineering to flatten the mounting bracket at the corners is needed if it physically cannot pull up tight enough.  This can happen if a quarter panel or patch panel has been welded to the car.

Actually, lay the panel down , inside down-outside up. Apply downward pressure with hand or foot to each edge, so as to decrease the bend . This will increase the radius. Trial fit , readjust as needed. Seems to make em fit.