Difference in exhaust manifolds.

[fordconvert]

...and can someone explain how the choke affects the exhaust manifold? I'm not saying it doesn't, I just don't know what the relationship is.

My guess is sometime in the mid 70's they went to an electric heated choke so they no longer had the air tube and box in the exhaust manifold.

 

[BUZZ]

Acording to Mustang Unlimited's catalog they list a manifold that goes from 65-67 then another that goes from 68-73 that for use with "IMCO" carb. Maybe thats the difference? I know they have a big price difference the early one list for 119.00 the later one list for 189.00 but if your not using the stock carb none of that should matter.

 

[wallaka]

C0's (maybe C1's) are the 1.5" flat gasket.
C3's are the 1.5" donut.
C8's are the 2" donut.
I'm guessing that D4 or D3 is the next one, with EGR and what not. There's a later one with an integral catalytic converter too.

The C8 is the best one in my book. It has a larger interior diameter and is contoured a bit where the outlet is. There aren't any extra fittings or catalytic converters on it.

 

[l3n]

My guess is sometime in the mid 70's they went to an electric heated choke so they no longer had the air tube and box in the exhaust manifold.

Aha, that makes sense. I've only heard about water heated chokes, didn't realize there were exhaust versions too.



Thanks for the info.

 

[x21]

If I recall, I bought a 'new' 78 manifold from NPD. It still had a small hole at the top for the choke tube for my carb. It also had a really big threaded hole for some pollution control i am guessing (bout the size of a spark plug). It fit pretty nicely on the 66 head that I had too.

 

[Eric Rose]

My '62 had the flat gasket. The motor had been swapped to a '69 motor by the previous owner, so I guess they kept the '62 manifold.

I plan on cutting the flat gasket flange off of the downtube and welding on the doughnut gasket flange from the '78 motor I bought. The '78 manifold looks to be much better flowing, the outlet is twice the size of the original '62 outlet. There are 2 fittings in the '78 manifold for smog gear, but I have some brass pipe plugs for them. 8)

 

[Bort62]

My '62 had the flat gasket. The motor had been swapped to a '69 motor by the previous owner, so I guess they kept the '62 manifold.

I plan on cutting the flat gasket flange off of the downtube and welding on the doughnut gasket flange from the '78 motor I bought. The '78 manifold looks to be much better flowing, the outlet is twice the size of the original '62 outlet. There are 2 fittings in the '78 manifold for smog gear, but I have some brass pipe plugs for them. 8)

Have fun with that. The cast iron of the exhaust manifold welds like doggie-doo.

Why not just get the later manifold? Or a header...

 

[wallaka]

My '62 had the flat gasket. The motor had been swapped to a '69 motor by the previous owner, so I guess they kept the '62 manifold.

I plan on cutting the flat gasket flange off of the downtube and welding on the doughnut gasket flange from the '78 motor I bought. The '78 manifold looks to be much better flowing, the outlet is twice the size of the original '62 outlet. There are 2 fittings in the '78 manifold for smog gear, but I have some brass pipe plugs for them. 8)

Have fun with that. The cast iron of the exhaust manifold welds like doggie-doo.

Why not just get the later manifold? Or a header...

I would hope that he's talking about the downpipe that is the exhaust pipe, not the flange on the manifold itself.

 

[Bort62]

Ahh yes. Read twice reply once?

Something like that?

 

[Eric Rose]

I would hope that he's talking about the downpipe that is the exhaust pipe, not the flange on the manifold itself.

Yeah, just the exhaust pipe

 

[sixpony]

I replaced the warped and cracked stock 66 ex manifold with a 68 scott drake repro, I've been told the 68 is a more free flow design and is also set up to use a 2" exhaust pipe, I hope this is right because I'm getting ready to build a system using a 68' headpipe, flange, etc. The parts catalogs list a 66 doughnut gasket as 1 3\4" and the 68 as a 2" same as the 289 doughnut.

Oh, and the new manifold also has the hole for the choke heat tube, perfect bolt on. and appears to be much beefier than the original!

 

[wallaka]

I replaced the warped and cracked stock 66 ex manifold with a 68 scott drake repro, I've been told the 68 is a more free flow design and is also set up to use a 2" exhaust pipe, I hope this is right because I'm getting ready to build a system using a 68' headpipe, flange, etc. The parts catalogs list a 66 doughnut gasket as 1 3\4" and the 68 as a 2" same as the 289 doughnut.

Oh, and the new manifold also has the hole for the choke heat tube, perfect bolt on. and appears to be much beefier than the original!

It is. The 68 has reinforcing ribs cast in. All in all, a much better piece.

 

[Williboy]

The 68 is also beefer at one area than the earlier manifolds. Less prone to cracking. It does use a different gasket but the muffler shop had the flange.

 

[grocery getter]

I have a c8 fomoco manifold i'll sell ya'...let me know if you're interested.

 

[wallaka]

Here's a C3 and C8 casting for comparison. Rusty one is the C8. Notice how beefier the C8 is at the top of the siamesed ports, and the outlet diameter.