3890462 heads

[Joe L.]

Re: 3890462 heads

Joe,

By a pattern number I assume you mean the number after the "GM". If so, I always believed that to be the mold number.

Dave

Dave------


Yes, I am referring to the number after the "GM" (or, sometimes after "GMT" for Tonawanda castings).

Blocks and cylinder heads, as well as most other cast iron parts, are SAND CASTINGS. For a sand casting, the mold is made of sand and its use is definitely one-time-only. However, the sand mold is made from what is referred to as a PATTERN. The patterns are used for making numerous sand molds over a period of time. So, the number has to identify the pattern and not the mold. If it identified the mold (i.e. sand mold), the numbers would get into the millions because, as I say, the sand molds are a one-time-only sort of thing.

Many (but not all) aluminum castings are permanent mold or die castings. In this case, the molds are durable and re-usable. So, in this case, the number represents the actual mold number.

Can anyone tell us an example of a rather unusual ALUMINUM SAND CASTING used on a Corvette? There are not too many of this type of casting. Aluminum intake manifolds are the most common but there are a few others.

[Joe L.]

Re: 3890462 heads

Thanks Joe. So would the odds be that a cars heads would have the same pattern number or is it just chance?

Keith------


One more thing: the ONLY way to know what pattern numbers were originally used for the cylinder heads, block, and other cast iron castings on a particular car is to have the KNOWN-ORIGINAL castings used on that car. There is absolutely no way to otherwise know. Period.

[David L.]

Re: 3890462 heads

Can anyone tell us an example of a rather unusual ALUMINUM SAND CASTING used on a Corvette? There are not too many of this type of casting. Aluminum intake manifolds are the most common but there are a few others.

Joe,

Are you referring to lost foam casting? Years ago when my wife was buying a new 2000 Saturn I remember the salesman explaining that the aluminum block was cast using polystyrene foam. I remember block had a very smooth surface.

Dave

[Joe L.]

Re: 3890462 heads

Joe,

Are you referring to lost foam casting? Years ago when my wife was buying a new 2000 Saturn I remember the salesman explaining that the aluminum block was cast using polystyrene foam. I remember block had a very smooth surface.

Dave

Dave-----


Lost foam castings were not used on Corvettes, at least not through 1996. I'm referring strictly to aluminum sand castings. Most aluminum castings on a Corvette are permanent mold or die castings. A few are sand castings, though. As I mentioned, C1-C4 aluminum intake manifolds are one example. Other examples are the aluminum heads used on some 67-71 big blocks, ZL-1 blocks, and 1987-96 aluminum heads. However, there's at least one other aluminum sand casting used on Corvettes.

[Keith L.]

Re: 3890462 heads

Interesting. For what it's worth both of the 462 heads are the same date and pattern number. Curosity is going to make me check some of my cars.