My dad and I have been talking about possible resolutions to this engine noise issue we’ve had for months. At one point, I suggested that we ask Dino Fry (the guy who dynoed the engine for us) if he would be willing to stop by and help us diagnose the issue. My dad stopped by his shop and asked, and he was more than willing to come down.
We fired up the engine and almost immediately Dino said it sounded like lifter noise. That is what it has always sounded like to me too, but we replaced the lifters with no change to the sound. We pulled the rocker arm covers one at a time, and Dino used a timing light and screwdriver held up to his ear to analyze each rocker arm in turn. The #1 intake rocker and #4 exhaust rocker sounded different than the other six on that side, so he decided to adjust them with the engine running to see if he could get them to sound the same. Sadly, despite adjusting them so they all sounded the same, the engine noise persisted.
Despite that, he suggested we do the left side of the engine just to be sure. We pulled the valve cover and he repeated the adjustment for #5 through #8. While adjusting the rockers for #5 and #6, we heard a slight change to the sound. After letting the engine cool a bit, he loosened and reset the preload on the #5 intake lifter and suddenly the sound was gone! Sadly, the sound returns when you rev up the engine, but no longer occurs at idle. At this point, it’s pretty clear that we have another bad lifter. My dad is convinced that Crane just boxed up our original lifters and sent them back to us. It’s hard to imagine that two sets of lifters from them would be defective in the same way, so I’m inclined to agree with him. Regardless, we’re now certain that the noise is coming from the lifters, so we’ll be replacing them with something other than Crane lifters.
For now though, the engine is back together and runs nice and smooth (at least at idle)!