340 Ultrasonic Wall Measurement Sanity Check

The cast date I have written down is 6/18/67 so it's an early block.

My problem is with the interbore measurements with both our blocks- they are not possible in some locations. For example on your 360, #5-#7 depth B is .246 on one cyl and .247 on the other. Together that's. 0.493 worth of metal not including any core thickness. The maximum wall thickness between the bores on a 360 is 0.46 [= 4.46 (bore centers) -(2* 1/2* 4.00 bore diameter)]. That's reading .033 more metal than possible and no waterjack thickness. Same with my measurements- the sum total of the interbores come out to a number with little to no waterjack thickness possible. That leads me to think the probes are over estimating thickness a bit.
Rusty- with your probe are you getting something less than we are in the interbores?
The testing lab that did my sonic check above was rather large, long established, and costly, and seemed unfazed by the requested procedure.
But I cannot dispute nor explain your math in reference to the reported figures.
Good Eye BTW.