exhaust manifold numbers

[tonys_shelby]

I'm sure this have been gone over a lot in the past but maybe has been erased over time.  The exhaust manifolds for my '67 GT500 are in terrible shape and not able to read the numbers and really not even sure if they are correct to begin with. So i need to fine a good set.   I see conflicting posts of what the car should have, GT390 manifolds, specific to 428 ones, etc and It should have C6OE or C7OE drivers side witch one etc.  Then there is the from a mustang only 390 engine? So what #'s should it have and how to tell if it will fit in the Mustang etc.  It has the correct 14 bolt heads and was built in Jan '67 in case they changed through the year.  Any help will be great

[Bob Gaines]

I'm sure this have been gone over a lot in the past but maybe has been erased over time.  The exhaust manifolds for my '67 GT500 are in terrible shape and not able to read the numbers and really not even sure if they are correct to begin with. So i need to fine a good set.   I see conflicting posts of what the car should have, GT390 manifolds, specific to 428 ones, etc and It should have C6OE or C7OE drivers side witch one etc.  Then there is the from a mustang only 390 engine? So what #'s should it have and how to tell if it will fit in the Mustang etc.  It has the correct 14 bolt heads and was built in Jan '67 in case they changed through the year.  Any help will be great

Typically they are C7OE-A passenger and C6OE-A driver. They were predominantly used on 390's besides certain 428 applications so they are relatively available. They weren't just used in 67 on Mustang's. 67 Comet and Fairlane . 69-70 used a C9OZ-B on passenger side. The full size cars manifolds which will not fit typically were marked with a different casting number.

[tonys_shelby]

awesome  thanks Bob!

[Mike James]

I do have a spare C7OE-9430 manifold with 6M15 date. Was sitting in the back of my car when it was rescued 20 years ago.  It's in great condition but should be bead blasted and surfaced at a machine shop.  Remember, no manifold gaskets needed so it is a good idea to surface them.  I also know of a good trick (don't shoot me concours guys), you can apply a little dab of copper high temp gasket maker to each head port surface and they will also seal up nice for stubborn leaks. 

My car came from a life in southern Texas and southern Arkansas and had no rust, there is no pitting on this single manifold.  Not really looking to sell but if someone is in a bind and needs it let me know.  Maybe someone out there needs just one manifold, who knows?  I bought a matching set from Bob Gaines (which worked great) so don't need this single manifold.

[Bob Gaines]

I do have a spare C7OE-9430 manifold with 6M15 date. Was sitting in the back of my car when it was rescued 20 years ago.  It's in great condition but should be bead blasted and surfaced at a machine shop.  Remember, no manifold gaskets needed so it is a good idea to surface them.  I also know of a good trick (don't shoot me concours guys), you can apply a little dab of copper high temp gasket maker to each head port surface and they will also seal up nice for stubborn leaks. 

My car came from a life in southern Texas and southern Arkansas and had no rust, there is no pitting on this single manifold.  Not really looking to sell but if someone is in a bind and needs it let me know.  Maybe someone out there needs just one manifold, who knows?  I bought a matching set from Bob Gaines (which worked great) so don't need this single manifold.

Besides machining I always add a thin spread of high temp silicone (same as the copper gasket maker)for extra insurance. If any squeezes out it is easy to get rid of with a razor blade or pick tool . Back in the day we did many a backyard machining of the exhaust manifolds mating surface by grinding them them in a circlular motion on a flat concrete driveway slab.

[1967 eight barrel]

Bob, what state are you from?     I suppose that would work in a pinch. How many hours did it take to get a flat surface?
I think the high temp sealer is just wise. There is little worse to work on than headers or iron exhaust manifolds on a big block.

[Mike James]

Bob's story is priceless.  He needs to get everything he knows about these cars into a book!

[Bob Gaines]

Bob, what state are you from?     I suppose that would work in a pinch. How many hours did it take to get a flat surface?
I think the high temp sealer is just wise. There is little worse to work on than headers or iron exhaust manifolds on a big block.

The Show Me state. I smile when I think back on some of the things we did when building engines and restoring cars back then compared to now. That backyard alternative is only meant for minimal warpage and as a insurance policy in the same way the thin silicone smear was/is. It would only take about five to fifteen minutes to grind. You could easily see within that time if the manifolds were warped to a point where they might not seal properly.It was something we did back in the day when we didn't have access to a grinding table at a machine shop. It did work well in a pinch. It was certainly better then not doing it considering the possible negative results . I have a machine shop that is about 1 mile away from me now ( 25 years now) so I haven't done the backyard grinding for some years. 

[roddster]

  Well go firgure.  I have a 390 GTA coupe that the motor locked up on back in 1979.  The Oklahoma car has been sitting since.  A couple of years ago I took off both exhaust manifolds, sand blasted them...only to find both had stress cracks about smack in the center.