It's certainly a cylinder head (gasoline fueled), and I'll just add farm and industrial tractor to list.  It is also what is known as a flathead, in that intake and exhaust valve mechanism with cam shaft and often pushrods now arrayed above cylinder head was in this motor within cylinder block.  That fact probably dates it back before 1940s. But, of course, somewhere they are probably still turning out flathead motors.  The size of the spark plug holes might be some indication of age.  The fact that there also does not appear to be an allowance for a thermostat on the water intake/outake might suggest some antiquity.

joe dent
american university  

-----Original Message-----
>From: Stacy Kozakavich <[log in to unmask]>
>Sent: Oct 3, 2006 7:06 PM
>To: [log in to unmask]
>Subject: Machine Part ID?
>
>Hello Histarch-ers,
>
>I'm inspired by all the industrial machine/process expertise we 
>evidently have on this list to make an appeal for help in identifying an 
>artifact found this summer at my ca. 1885-1935 dissertation research 
>site in Tulare Co., California: It's a cast iron object which looks like 
>some sort of cylinder head, and measures very roughly 10" x 6" x 1.5".  
>The number on the top view is "6251[?]1-4."
>
>Pictures here:
>https://webfiles.berkeley.edu/stacyk/public_html/Machine_Part.jpg
>
>Any ideas on what kind of engine/machine this may be from?
>
>Thanks!
>Stacy Kozakavich
>
>Ph.D. Candidate
>Department of Anthropology
>University of California, Berkeley