engine vibration
 

I have a 388 its just a 383 with a 60over bore. anyway I am experiencing a vibration at 2000-3000 rpm it idles fine and pulls very well this is just a bit unusual. ny ideas would help.

383 balance issue
 

Is this under load in gear, or just revving in nuetral?

How did you balance your 383? What damnr, flywheel or flexplate did you use?

It has a 400 balancer and flywheel. I had it all balanced and it would great for the past 8m months. this is just an issue that has come up. Was going to open the valves covers today and see if it was the rockers coming loose.