Hi all,
I have a '94 Accord LX Auto that back in December that I replaced a valve and valve spring. (https://www.hondaaccordforum.com/for...ad.php?t=29602) About the same time after it was running again, there was a hole in the exhaust so I took it in and they replace from the Cat back (replaced a resonator with a pipe because he said I didn't need it...). Son took the car to school and is now home for the summer. I drove the car the other day and noticed it has a vibration at higher RPM's and when accelerating hard.

These are my thoughts of what might be causing this:
1) Harmonic belt - marked the location on the pulleys of the old belt, but did not stick in the pin etc to line it up per the manual. If it's off, it would only be 1 or 2 teeth...
2) I set the rocker arm adjustment screws, but not sure how that would cause a vibration...?
3) Exhaust system - maybe something resonating?

Any thoughts on what this might be?