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Casting the block upside down? I also live in the Chevy world (63 Impala), and I read that GM poured their heads upside down at the foundry so that the heavier iron particles would migrate to the valve seat areas for greater strength and durability at the upper deck of the heads where all the reciprocating and valve seating took place over 200,000 miles.
Did Henry (or other manufacturers) utilize a similar method? |
Re: Casting the block upside down? Sure has been a lot of the 'C' word used here lately....:(:eek::p;)
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Re: Casting the block upside down? the first thing that comes to mind is, do Iron particles come in different weights? I've never cast iron, so I don't know much about it. However, I should think that the viscosity of the molten iron would be a more important criteria. Blocks and heads are fairly complicated shapes to pour and the engineers may have decided that you are better off with the metal at the bottom (top) being poured first. Just a guess.
Terry |
Re: Casting the block upside down? In a film about Ford, they were pouring the blocks right side up & pouring them while MOVING on a conveyor, using smaller pots of molten metal that also moved on an overhead conveyor!! AMAZING STUFF!!! Bill W.
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Re: Casting the block upside down? What you heard is an old wives tale. They may be poured upside down but that would only be to insure that all areas are filled. This is determined by the gates and vents more than which side is up. There isn't time for any particles to "settle", the iron (or aluminum) sets to quickly for that.
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Re: Casting the block upside down? Could you cite the source of this misinformation? Sounds like typical misinterpretation of fact by a writer or reporter devoid of the appropriate technical background.
Common considerations for foundry practice to produce sound castings and subsequent machining would include pattern design of section thickness transitions for directional solidification, ease of sand core production and placement, sprue runner and gate design for laminar flow, type of automated molding production equipment you have, what surfaces will be 'as cast' and which surfaces machined, and the list goes on and on. There is no migration of 'heavier' iron particles. Density is controlled by directional solidification and rate of cooling. That determines soundness (lack of porosity) and grain size. |
Re: Casting the block upside down? If there is some truth to this I would be more inclined to believe a different type crystal structure was formed at the bottom of a pour then the top. As mentioned, no you are unlikely to have much if any movement of "heavier' metals. I believe the strength is more based on the ratio elements and how the crystals are allowed to form.
The would be more pressure from the molten metal above and maybe you got a finer crystal structure? I am NOT by any stretch a metals engineer that knows about casting issues. So I am doing more of an educated guess based on some stuff I learned reading about babbitt. I would think that when Ford was pouring they did not fully understand all the processes involved, but by the 60's I would think they might have adopted practices based on better knowledge. So I would think that it is plausible that there was a metallurgical reason for casting the valves section at the bottom. For example with the babbitt. You want the transitions from solid to liquid and liquid to solid to be fairly rapid to prevent the formation of larger crystals of certain types. You want lots of small crystals bound together for the best bearing. Large crystals can be start points for micro cracks which lead to big cracks. |
Re: Casting the block upside down? Steve, some of us own both brands....
go ahead-say it cccchhhheeevvvvyyyyyy! see, it wasn't that bad?????! |
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Re: Casting the block upside down? Wives tale.
When it is poured, the metal is in Liquid state. That would be like looking for heavier water bits...... |
Re: Casting the block upside down? All substances differ in their molecular composition. Cast iron, in its' liquid state would have suspended particles of various elements, some heavier than others ie. lead, mercury etc., being heavier than iron. Remember, cast iron is a very "crude" and "impure" metal. Just as there are many different chemicals in water that are heavier than the H2O itself. It's called the PH scale. Oil floats on water, ice floats on water, hot air ballons float on cold air, the water in a hot water tank is hotter and thinner at the top, and colder and more dense at the bottom. The same is true with molten metal. There are many things in the physical realm that we can't see, but they are still there. IMO as for a cylinder head being deep enough for measurable heat stratification for heavy particle settling during the casting process, it would seem quite negligible.
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Re: Casting the block upside down? Only a Chevy guy could gullible enuf to be conned with information like this ! Yes it is a wive's tale or old dog's tale !
Al |
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Re: Casting the block upside down? How many old wives tale have we model Aer's fallen for?
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Re: Casting the block upside down? 1 Attachment(s)
http://theoldmotor.com/wp-content/up...16-Valves1.jpg
I rebuild early brass era and racing engines and have worked w/a pattern maker to make patterns to cast several blocks ( A Packard and Duesenberg racing car) which I then machined. Before we made the patterns I did a lot of research and found the same thing, casting heads or block upside down (combustion chamber down) was the best way. The reason being that any air bubbles would tend to float up in the molten metal and not leave any pinholes or defects in the combustion chambers, which as we all know have to with stand high pressure. Read about it in the thumbnail photo below from High - Speed combustion Engines by Heldt. Photo of the 16-valve Duesenberg block I had cast and then machined here in our shop. More photos here. And more info on the car and engines here. Photos of the car be seen of the car and engine can be seen here out in front of our shop Hemmings Blog and if you are interested, many more photos of the car at concours and races. |
Re: Casting the block upside down? The bubble thing makes sense
Ford, Chevy, Peterbuilt, Honda, Daimler, Jeep There I said it |
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The thumbnail photo below shows some of the pieces of the cut-up blocks in a corner of the shop |
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