Ford 300 Inline Six

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Steamchick

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Clever! Sounds a bit like "lost-wax" casting work, but in a machining context. New to me, but I'm sure I'll find a use for this process. You can buy hot melt resin - a friend has some for pipe bending - that may work and be re-usable, being hot-melt. Or lead can be used I guess?
K2
 

mayhugh1

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I decided on a stock-looking exhaust manifold rather than fabricating a tubular header. Although the full-size castings evolved over their production life, there were two basic varieties of exhaust manifolds used on the Ford 300. George's design is based upon the most common one which used a 2" exhaust flange exiting the heat riser at about 45 degrees. A less common heavy-duty version was used on one-ton trucks and had a 2-1/2" exhaust flange pointing nearly straight down. The heavy duty manifold was popular among performance enthusiasts not only for its freer flow but its better compatibility with aftermarket turbochargers.

My scaled-down manifold is based upon the heavy-duty version although I took liberties with its design to keep its machining reasonable. If accurately scaled, the tiny cutters required for its cooling ribs would have required an inordinate amount of machining time. I also left the exhaust flange as an add-on.

Work began with the preparation of a suitable 6061 workpiece. After planning its location inside the oversize workpiece, the manifold's numerous internal passages were drilled and reamed through the outside faces of the workpiece. Plunged ball cutters were used to blend the 90 degree corners for a smooth exhaust flow.

Precisely cut aluminum plugs inserted through the faces of the workpiece sealed the passages at what will eventually become the exterior surfaces of the manifold. These aluminum plugs were bonded with high temperature 620 Loctite and cross-pinned for good measure with TIG rod. The aluminum plugs and pins should be invisibly blended into the surfaces of the manifold during its machining.
In Loctite jargon, aluminum is an inactive metal, and so primer was used on both the plugs and pins. Unlike paint, Loctite bonds only to bare metal, and its primers are just copper salts suspended in a volatile solvent. These primers are intended to leave metal ions on the bare surface of at least one of the metals in a bonded pair in order to kick-off the curing process in a timely manner.

The next step will be to finally begin the manifold's machining. - Terry

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a41capt

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I decided on a stock-looking exhaust manifold rather than fabricating a tubular header. Although the full-size castings evolved over their production life, there were two basic varieties of exhaust manifolds used on the Ford 300. George's design is based upon the most common one which used a 2" exhaust flange exiting the heat riser at about 45 degrees. A less common heavy-duty version was used on one-ton trucks and had a 2-1/2" exhaust flange pointing nearly straight down. The heavy duty manifold was popular among performance enthusiasts not only for its freer flow but its better compatibility with aftermarket turbochargers.

My scaled-down manifold is based upon the heavy-duty version although I took liberties with its design to keep its machining reasonable. If accurately scaled, the tiny cutters required for its cooling ribs would have required an inordinate amount of machining time. I also left the exhaust flange as an add-on.

Work began with the preparation of a suitable 6061 workpiece. After planning its location inside the oversize workpiece, the manifold's numerous internal passages were drilled and reamed through the outside faces of the workpiece. Plunged ball cutters were used to blend the 90 degree corners for a smooth exhaust flow.

Precisely cut aluminum plugs inserted through the faces of the workpiece sealed the passages at what will eventually become the exterior surfaces of the manifold. These aluminum plugs were bonded with high temperature 620 Loctite and cross-pinned for good measure with TIG rod. The aluminum plugs and pins should be invisibly blended into the surfaces of the manifold during its machining.
In Loctite jargon, aluminum is an inactive metal, and so primer was used on both the plugs and pins. Unlike paint, Loctite bonds only to bare metal, and its primers are just copper salts suspended in a volatile solvent. These primers are intended to leave metal ions on the bare surface of at least one of the metals in a bonded pair in order to kick-off the curing process in a timely manner.

The next step will be to finally begin the manifold's machining. - Terry

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Boy, that’s gonna leave one hell of a mountain of swarf! I can’t wait to see the finished manifold, your CAD drawing looks amazing.

John W
 

Thommo

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G’day from Oz. I must say Mayhugh1, I’m loving this project. When I was a kid, iE 7, my Mum, Dad and I traveled around Australia in an F100 and caravan. The F100 had a 300ci 6 cylinder and a four speed box. That beast was loaded up with everything that we owned in a big cage that went up and over the cab. We traveled a lot of miles in the old girl from 1974-1980 and she didn’t miss a beat. Imho those engines were some of the very best made by Ford. I’m really looking forward to seeing and hearing your engine when she finally fires up. Fantastic work!😃
 

kvom

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What material(s) for the pins and plugs?
 

mayhugh1

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The exhaust manifold's machining steps were similar to those used on the intake manifold. Differences in its size and shape, though, made things a little more challenging and at times confusing. As the exhaust manifold took shape, it would have become more and more difficult to fixture it as a standalone part. So, unlike the intake manifold, all its machining was done through five faces of the workpiece. The manifold wasn't released from the workpiece until all its machining was completed.

The manifold's ribbed outer surface was machined first. Since the top surfaces of all six runners were also accessible in the same setup, they were machined as well. A long stick-out 1/4" end mill was used for roughing, but the filleted surfaces were finished with smaller diameter ball mills. Special long reach 1/16" cutters running on a high speed 5-axis machine would have been needed to finish a faithfully scaled manifold. Mine was designed around an 1/8" ball cutter running on a Tormach.

Chatter from the long roughing tool was so annoying that I'd normally have left the shop while it was running. As luck would have it though, my Micro-drop coolant dispenser died shortly after starting, and I had to manually spray coolant and blow away chips during the entire two hour run. Fortunately, surface finish wasn't an issue since the operation was set up to leave .007" excess stock for the finishing tools. Total machining time through the first face of the workpiece was about five hours.

The trough left around the semifinished part in the first setup was filled with Devcon 5 minute epoxy in order to keep the part safely suspended inside the workpiece for the rest of its machining. The runners were designed so the counterbore locations needed for the mounting bolt heads would be accessible in this same setup so the special tool used on the intake manifold wouldn't be needed. Their exact depth was critical for the shared mounting bolt scheme used by Ford to attach the manifolds to the head. These were plunge milled once the epoxy had cured.

The manifold's much simpler rear surface was machined in the second setup. This step left the semi-finished manifold securely suspended inside the workpiece by only the epoxy. The mounting flanges and bolt holes were completed in the third setup.

The filleted surfaces immediately below the runners were machined through the fourth face of the workpiece using a long reach ball cutter. This simple finishing operation was done on my Enco mill so I could continually adjust the tool's feed rate and minimize chatter. A portion of the workpiece had to be milled away in order to get the spindle as close as possible to the runners for minimum tool stick-out.

The heat riser cavity was opened up in the fifth and final setup. Another chunk of workpiece had to removed for its access. A mounting recess, machined for the add-on exhaust pipe flange, was shaped to avoid any awkward intersections with the embedded pins and plugs in this rather busy area. The manifold's total machining time worked out to about ten hours.

During the original preparation of the workpiece, I decided on aluminum pins to backup the Loctite'd plugs used to block off the ends of the numerous internal passages. After noticing a black spot that showed up during the heat riser's machining, I thought one of the pins had not been inserted far enough. The spot turned out to be a steel pin that had been mistakenly used in this particular location.

A trial fit of both manifolds to the head without the use of the flange gasket showed the mounting screws shared between them appeared clamp both flanges equally. The flange thicknesses may be fine tuned later after more careful measurements. Both water and compressed air were used to sanity check the continuity of the exhaust passages through the heat riser.

The extended exhaust pipe flange was machined from 12L14 and permanently attached to the bottom of the heat riser. In addition to a pair of mounting screws, the mating surfaces were coated with Loctite 620 for a sealed bond which should stand up to the engine's exhaust heat.

After temporarily plugging all its openings, the entire manifold assembly was glass beaded to give its surface a cast iron appearance. However, the aluminum's natural color is wrong for an iron manifold. I have some POR-15 dark gray paint intended for exhaust manifolds, but it's gotten pretty thick over the years. I've ordered the special solvent this paint requires, and after some testing I may air brush the manifold with it.- Terry

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kvom

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No one will peer underneath the manifold to see that pin.
 

cwelkie

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Phenomenal result from very thoughtful setups!
 

minh-thanh

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mayhugh1 !

PERFECT !
There will be one more masterpiece
I have a question about pictures of your projects .
Did you post it directly on the forum or was it quoted from another source ?
 

mayhugh1

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mayhugh1 !

PERFECT !
There will be one more masterpiece
I have a question about pictures of your projects .
Did you post it directly on the forum or was it quoted from another source ?
Hi minh-thanh,
I upload all my project photos using HMEM's photo posting/storage service. I find this technique most convenient and 'safe' for my usage. I don't cross-post into other forums, and so storing my photos this way will let them live as long as the posts. - Terry
 

ddmckee54

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Terry:

I hate to do this, but I've got a question for you from a couple of posts back - when you were maching the manifold backside I believe. In image 191.jpg you've got something inserted into the exhaust openings. I assume this was done to keep the crap out of the openings? Or was there a different reason, and what were they? It's not important, I'm just curious since I haven't been able to figure out what they were.

Don
 

mayhugh1

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Terry:

I hate to do this, but I've got a question for you from a couple of posts back - when you were maching the manifold backside I believe. In image 191.jpg you've got something inserted into the exhaust openings. I assume this was done to keep the crap out of the openings? Or was there a different reason, and what were they? It's not important, I'm just curious since I haven't been able to figure out what they were.

Don
Don,
You're right. They're silicone plugs to keep the chips out of the internal passage during machining. I bought them from Amazon:



They've turned out to be one of the handiest items to have around my shop. _Terry
 

jlchapman

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Terry,
Your work on this engine is awesome. I'm really interested in trying your epoxy method of holding parts while machining the part. What do you use for an oven? Can I use a convection toaster oven?

Jerry
 
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