3800 white or wheat?

Turbocharged400sbc

3800 & 4T80E > ALL
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Jun 16, 2007
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hangover park IL
sliced2261casting8.jpg




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 ;)

sliced2261casting2.jpg


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)

sliced2261casting6.jpg
 

Turbocharged400sbc

3800 & 4T80E > ALL
TCG Premium
Jun 16, 2007
32,541
15,849
hangover park IL
the pen is pointing the the casting # location...i got both of them sliced and drilled...to tell you the truth...i didnt see many differences between the two, yes there are differences but not many



i did find some area's where the head deck thickness was just a 1/4 inch where most of it is 5/16ths, definatly not super strong....i think i may have found a way to add a fifth head bolt to each chamber...we'll see what i can do...



late4781castinglocation.jpg




the interesting thing is i believe it would be possible to weld up the guides and remachine the heads for splayed and canted valves but i think the limit would be about 4 degree's before the material gets questionable...
 
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