sonic checking blocks

Is it worth it? Think of it like this... If you spend $100 to magnaflux a block and it passes, was it worth it? Why? If it falis, you're only out $100. If it passes, you say it's cheap insurance. When the blocks were still easy to find, and the collectors werent driving prices to ebay levels, it was common to not worry about it. But, with std bore core blocks getting harder to find and more expensive, knowing if that .030 over block has the meat to work for you is important. Add to that the typical Mopar casting core shift, and it becomes more important as the hp level rises. I own a tester. I shopped around, and found a big difference in the quality of the testers. I bought mid to high grade. The cheap ones are as reliable as plastigage for checking thickness. And the company I bought gave a little over the phone training course on how to use it right. Expect to pay anywhere from $75-$200 for the test, and be aware that many shops that sell the service, dont own testers. Ask to see it, or watch the test. I found that out before I bought mine. It takes me about 2 hours to do a block. If they give youa sheet with four readings for each hole, find another shop. You are looking for trends in the casting, not just the thinnest spot. I have found factory blocks as thin as .090 on the pin axis direction, and under .120 on the major thrust. And that block was standard bore. That block got a sleeve. So for my customer, it made a huge difference. We had to go .060 over in that block because of rust pits. Had we not sonic tested, I'd be building a 4" stroked time bomb. But it would have looked great going together. In a modern shop, a sonic tester and someone who knows what it does, and how to use it is mandatory.