The flapper box replacements out there are not the same as original. They look about the same but the angle of the outlet is different by 25 degrees.
This may not be noticed by most people because the flexible hose used to attach them to the chassis takes up the difference.
The heat exchanger option for my headers relies on hard mounting the flappers to the chassis instead of to the h/e box.
The new flappers won't work in this orientation. My wye tube doesn't fit.

like this

Why not simply replace the orange hard mount with a hose? Does it have to be that way?

They have to be firmly supported for the flappers to operate. The factory mounted them to the heat exchanger body via the warm air elbows. My setup doesn't work that way.

Can you fab a new J-pipe to replace that piece?

I think I need to make the orange tube with a 25 degree bend built in.

That's what I meant but probably called it by the wrong name...

Bummer, did you have a bunch made up?

Chris - can't wait, it's like Christmas is July!!!!

-pt

I have a good number of the orange powdercoated tubes.
Now I need to keep another style in stock.
Here's what I came up with. It moves the flapper closer to the firewall but appears to be ok.

That's a lot of work. I mounted some right on the hard tube on the chassis. What I did on one install was use to swap sides (left flapper on right, etc), grind off the lever, re-index it, and weld it back on. Worked fine, and IIRC they were new ones like the photo.

I'm not sure I get this... isn't the engine and tranny meant to move/vibrate in the engine and tranny mounts and hence, wouldn't that cause problems with a fixed solution like this?

You can probably get away with that method on a six chassis but not a four.
Click to view attachment
I already have to flip and re-index the arm on the driver's side for it to work with my single heat exchanger.
It looks like the angled tube is the way for me to go with the new replacement flapper on the passenger side and no need to re-index the arm.
Click to view attachment


The flexible tube goes from the flapper to the exhaust system instead of from the flapper to the body. It makes more sense this way because the actuating mechanism is no longer affected by engine movements.

Ahhhhhhhhhh... very cool (or very hot). Now I need a solution for my 914-6 heat exchangers. I was going headers but I now have a pair of HE's.

I just jammed the /4 flappers on my /6 HEs. Not the greatest fit, but then I'm a backyard barbarian mechanic .... I do what works (kinda).

No, it was a '73 conversion car. I did have to shorten the cable.

Notice the angular shape of the cap where the hot air is dumped compared to the more rounded shape of the original. These replacements have been out for 20 years I think. I''ll check the angle on my stock.