I recently installed 1.6 rockers on my motor, and when I floor it, I hear a weird crunch/pop noise when I shift at around 6000 RPMs. I know sometimes piston/valve clearance can be an issue, so I was wondering what it sounds like when this actually does happen. Thanks.

 

Like a broken engine.

 

It sounds REAL EXPENSIVE.

If this sound happens on anything remotely resembling a repetitive basis, it isn't caused by valve-to-piston clearance issues.

 

Expensive is the best answer.

You won't hear a piston hitting a valve however if the piston does hit a valve, there's a very good chance the valve(s) will be bent. You'll then hear noises in the intake or exhaust because the valve doesn't close on the seat.

Going to a higher ratio rocker without checking clearances can bring on other problems. Depending on the cam grind, a higher ratio will give a higher valve lift however if the springs are not designed for the extra lift, they will bind. Also with higher lift, the valve guide needs to be cut down enough so that the bottom of the spring retainer doesn't hit the top of the guide/valve seal.

Spring pressures need to be high enough to keep the valves from bouncing on the seats when they slam closed (valve float). If the valve bounces open when the piston is at or near TDC, it will make contact.

When in doubt, pull your rocker covers off and look for any damage. Broken springs or retainers. Bent pushrods etc. Do a compression or leakdown test to see if the valves are seating.

 

Not familier with that cam but if your springs are the same stock springs that came on my AFR 195 heads... They're only rated for .550 lift.