Popping sound in exhaust

Did the machine shop that did the heads grind the valve tips to set the correct length measured from the valve spring seat to the valve tip?

The first 440 I rebuilt when I was a kid popped at idle. What I found was that when the lifters pumped up it held some of the exhaust valves open enough that when it fired it would pop. It turned out the machine shop didn't check the exposed length of the valve and essentially some were long and had to be ground. There is a spec for the length range.