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Anonymous
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Ignoring the late-model coffee-can exhaust manifolds, are there significant differences in exhaust manifolds as our small sixes evolved to the 200 and 250? Which flow the most?
Howdy Graeme:
Yes, there are differences, but after '62 model year none of the changes were to help performance. In the 1963 model year the exhaust manifolds were changed to a donut type gasket rather than the flat gaskets previouly used. These are a much better seal at the head pipe. The diameter of the outlet was also increased to 2" along with the od of the header pipe. Some where around '69, earlier in Calif Exhaust manifolds were cast to accomodate a variety of smog and air injection requirements to meet EPA. None of these changes helped performance, by themselves, they probably disruptied flow. Exhaust manifolds were beefed up over the years also to reduce or eliminate cracking, a real problem on early manifolds.
I've looked at and measured the volume of the cast manifolds and while the internal volume varies, it is not enough to indicate that flow is improved. Some have reported a larger(?) 250 manifold used in Econolines. I have yet to come across any.
I prefer a pre-smog exhaust manifold from around '66 to '68. It is my opinion that the bungs and ports cast into later manifolds disrupt flow even though the later manifolds have a greater interior volume.
Stock manifolds can be improved on in several ways; mill the mating surface flat, enlarge the individual port windows to at least gasket size, blend and direct transitions, open the outlet to leave a minimal lip for the header pipe, finally, coat the exterior with Eastman's high temp paint to hold the head in- high temp=high velocity.
Before you start on any cast manifold check it thoroughly for cracks. Also know that the best cast manifold is no were as good as a good set of headers.
That's my two cents.
Adios, David
Yes, there are differences, but after '62 model year none of the changes were to help performance. In the 1963 model year the exhaust manifolds were changed to a donut type gasket rather than the flat gaskets previouly used. These are a much better seal at the head pipe. The diameter of the outlet was also increased to 2" along with the od of the header pipe. Some where around '69, earlier in Calif Exhaust manifolds were cast to accomodate a variety of smog and air injection requirements to meet EPA. None of these changes helped performance, by themselves, they probably disruptied flow. Exhaust manifolds were beefed up over the years also to reduce or eliminate cracking, a real problem on early manifolds.
I've looked at and measured the volume of the cast manifolds and while the internal volume varies, it is not enough to indicate that flow is improved. Some have reported a larger(?) 250 manifold used in Econolines. I have yet to come across any.
I prefer a pre-smog exhaust manifold from around '66 to '68. It is my opinion that the bungs and ports cast into later manifolds disrupt flow even though the later manifolds have a greater interior volume.
Stock manifolds can be improved on in several ways; mill the mating surface flat, enlarge the individual port windows to at least gasket size, blend and direct transitions, open the outlet to leave a minimal lip for the header pipe, finally, coat the exterior with Eastman's high temp paint to hold the head in- high temp=high velocity.
Before you start on any cast manifold check it thoroughly for cracks. Also know that the best cast manifold is no were as good as a good set of headers.
That's my two cents.
Adios, David
A
Anonymous
Guest
Thanks David. As you may know, I'm in the process of assembling a turboed Oz-headed 200. I have a '63 manifold with the doughnut. It's in good shape and free of cracks. I plan to do a sort of Ak Miller--a "J" pipe to a '79 Buick carbed turbo. My machinist is surfacing the manifold and I'd planned to make about the same changes you suggest. Then, I'm going to have the manifold and related tubing thermal barrier coated, inside and out.
Sometime down the road a turbo header would be nice. Right now, I'm just worrying about getting it running. The old "proof of concept" objective.
Graeme
Sometime down the road a turbo header would be nice. Right now, I'm just worrying about getting it running. The old "proof of concept" objective.
Graeme
Howdy back Graeme:
It sounds like you're on the right track. The '63 manifold casting #C3 are lighter castings then later ones, and likely less interior volume than later castings, but that may be just right to keep flow velocity up for your purposes. Thermo coating the interior will also help retain heat and add to flow velocity. Best wishes on your project.
Adios, David
It sounds like you're on the right track. The '63 manifold casting #C3 are lighter castings then later ones, and likely less interior volume than later castings, but that may be just right to keep flow velocity up for your purposes. Thermo coating the interior will also help retain heat and add to flow velocity. Best wishes on your project.
Adios, David
A picture is worth a thousand works.
When Graeme says, "I plan to do a sort of Ak Miller--a "J" pipe to a '79 Buick carbed turbo." This is what he means. You can ignor the caption. Look at the black "J" pipe between the exhaust manifold and the turbo.
When Graeme says, "I plan to do a sort of Ak Miller--a "J" pipe to a '79 Buick carbed turbo." This is what he means. You can ignor the caption. Look at the black "J" pipe between the exhaust manifold and the turbo.
A
Anonymous
Guest
You might want to do some checking on the later (early 70's) manifolds....I would assume to get the maximum amount of flow that you would do some work like David said;
Then I would see how much it would cost to have it jet hot coated!
The point of using the later manifolds is that the early ones had a major problem with them cracking and breaking from wear & tear and the later ones Ford casted reinforcement ribs in them to stop this from happening.
Just my .02 cents
Later,
Doug
Then I would see how much it would cost to have it jet hot coated!
The point of using the later manifolds is that the early ones had a major problem with them cracking and breaking from wear & tear and the later ones Ford casted reinforcement ribs in them to stop this from happening.
Just my .02 cents
Later,
Doug
A
Anonymous
Guest
I'm going to go with the '63 on this "proof of concept".
We have a local performance coating operation--so I'll coat inside and out of the manifold, "J" pipe and down-pipe.
I know I can coat the outside of the turbine housing. Any thoughts on coating the inside? Seems to me it'd keep the heat in the exhaust and reduce underhood temperatures. I don't think the coating thickness is enough to mess up turbine-to-housing clearance. I'll check with the turbo shop in Tacoma tomorrow.
We have a local performance coating operation--so I'll coat inside and out of the manifold, "J" pipe and down-pipe.
I know I can coat the outside of the turbine housing. Any thoughts on coating the inside? Seems to me it'd keep the heat in the exhaust and reduce underhood temperatures. I don't think the coating thickness is enough to mess up turbine-to-housing clearance. I'll check with the turbo shop in Tacoma tomorrow.
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