i sliced down the middle of the guides on the center chamber and aliced the end cylinder a little more selectively to check out coolant passage wall thickness. i have yet to drill the many holes for measuring the wall thickness's in different locations so that i can compare the 2261 casting to the 4781.
2261 being the early 95-97 L36 only heads, and 4781 being the late 98+ L36/67 casting that has the meat for injector boss machining for the L67 in head injectors
i am looking for the casting number (and preferably a junk head) for the 96-97 L67 heads as well as i would like to know the same of the SIII L26/32 castings
dont worry i will be using the high res digicam for the good pics after drilling
also:
http://i131.photobucket.com/albums/p313/tu...261casting1.jpg
the valve inserted will be for checking the throat angles to balance mid/high lift flow...i sure hope the L36 4781 has thicker port walls.... (the casting number of our 98 and 99 L67 heads is the same 4781)