No, I did not have it sonic tested...no one mentioned core shift until after the latest engine rebuild, which did absolutely nothing!

As a matter of reference, the engine builder(AMT Performance in St. Louis)ran the engine on an engine stand to break in the cam, etc. for about 15 minutes or so at which time we had to shut it down because it had completely heated up the 55 gal drum of water we were using for coolant. Temp in the shop was about 45 degrees. We were able to verify that the water pump was pumping like crazy! Subsequently, they (AMT Performance) tell me, a week or so later they ran another freshly built 383 which was developing quite a bit more power than my stock rebuild and it never did get the barrel hot. I wasn't there to see this, but that is what he tells me and they (AMT) have no answers as to where all of the heat is coming from?

The theory that has been given to me is that the engine may have had a core shift from the factory that wasn't quite bad enough to not cool the engine when it was new but when the block was bored 30 over, enough material was removed to throw it over the edge to where it will not cool when idling. Seems far fetched to me that an engine 45 years old would still be with the same car if it had a core shift issue, however, I am now totally out of possibilities I can try to solve the problem. In the end, core shift or not, I believe my only fix now is to purchase a new engine. In fact, I would not feel comfortable using ANY of the parts from the current engine on any new short or long block that I purchased.

Does a core shift on this engine seem feasible? Basically, that means my new rebuilt engine is JUNK!

I can keep showing the car as I have in the past and drive on days that are not so hot, but man this really has me frustrated!