SAAC Forum

You are correct about the exhaust manifolds, however we are talking about the control valve/flapper, here, and it being original/factory/delivered on 1968 GT500 cars.

I wasn't fortunate enough to own a '68 GT500 when new, but I suspect this part, the exhaust flapper, was a nuisance part.  Springs probably got weak or broken, which caused noise.  The functional benefit was negligible.  It possibly was the source of exhaust leaks.  They got removed and discarded with most exhaust work.  Service departments probably chose the spacer alternative.

All of this boils down to--not many cars remained with their original valve/flapper.  I have noticed some highly original, unrestored '68 GT500s that have this part.  Those cars and the SA parts/assembly documentation cause me to strongly believe that it should be considered when concours judging.

   

Royce, the PI or P/C application listed in the Mercury MPC would be for just that: a big body police car.  However, the Cougar 390GT and Comet 390GT should share the same exhaust valve as the Mustang/Shelby.

Correction:  Comet would share Fairlane application.  Cougar would share Mustang/Shelby.

This exhaust control valve had different applications using different designs other than for this topic.  Examples:
Galaxy, T-bird, even trucks, as well as Lincoln; same function, but different design for their application.

The Ford Master Parts Catalog calls it "Exhaust Control Valve".  aka informally as "flapper".  No, not what you are talking about.

While we are mentioning the MPC, the original/factory installed part is C7ZE-9A427-B.  Those were cast with C7ZZ stamping. 
The MPC lists a service replacement of C6OZ-9A427-D for F body (flapper style). 
The MPC does list a "spacer" solid version (non-flapper) as C7OZ-9A427-B, however this spacer is designated for Fairlane (B body) only, not Mustang (F body).

 

I feel it was appropriate to begin this new topic instead of continuing:

SAAC Forum► The Cars► 1968 Shelby GT350/500/500KR► 428 PI Exhaust Manifold Question

Not only is it my long-time /observation/experience that original 1968 GT500s are equipped with the exhaust "flapper" control valve on the RH exhaust manifold of the 428 PI, the part is clearly supported by Shelby documentation.

 

Will send a photo to your # of what I have.
Don

I'll take it.
Don

See the bottom of this page for sources of thatYou cannot view this attachment.You cannot view this attachment. Cobra badge.  Your father and his co-workers had ample access to such kits through the dealership service/parts departments.  It has been added to the car at some point.  It is not factory.

Very cool car and photos.  You are one lucky guy.

Quote from: Coralsnake on April 12, 2024, 02:00:36 PMNo flapper and yes they appear to be dated too early

I don't agree with your flapper answer. 

That is the screw.  And, yes, that is a pricey way for you to go.
Good luck.

The head just isn't as thick as the originals, Royce.  Probably as close as one can get.
I can't say for sure if it is a 12; don't have a gauge.

They screw into the alloy reflector housing, into a cast boss, which is tapped to match the threads.  The blunt end is important so that the screw doesn't "bottom out".  One screw serves as the grounding point for the multi-socket wiring harness eyelet.  I've wondered if this grounding arrangement may contribute to the nagging taillight issues,

Here are originals to compare to Pete's catalog image:

we bought FJF reman. parts through the 80s in Tulsa.

If you will search, you should find a topic that discusses locating the snake fender emblem on the fender (measurements).

Thank you, Dan, for these closeup pictures of the choke cable bracket differences.  You enabled me to identify the "lazy Z" bracket which I have had for years.  Your knowledge is amazing.

Congratulations, Mike.
(and Vern)