Vibration between 1100 and 1500 rpm??
 

ok, the problem is stated in the title. I have just put in a 347 into an AOD car and I have this annoying vibration in every gear from about 1100 to 1500 rpm. It does it in neutral, in park, and while the car is moving. I turned the ignition off while going down the road and still got the same problem. The engine is balanced to 28oz and so the damper and the flexplate are matched to that...what do you think the problem might be? Do you think it wasn't balanced correctly when I got it or what? Does the converter have to be balanced to 28oz as well? Thanks for any help.

Make sure your crank pulley bolts are tight, never hurts to check, one day i found my pulley wobbling, and creating vibration, turns out it was loose, and only had 3 fasteners in it, also i put a cheap balancer on and it, with a new pulley, solved the problem, but since you have a stroker, i assume the balancer is alright, but if it does it in park, i'd start inspecting.

good luck on it.

A couple thing to check for, look at all the pulleys while the car in running in park and see that they are all turning straight, esp the crank pulley. Check out the motor mounts. Are they new? Are solid ones, or stock type ones? I've heard about solid motor mounts causing more vibration. Since you said it still happenes in park and neutral, then I don't see it being in the converter, but I could be wrong. Also whats your timing set at? Bad timing could cause it to run rough. Lets us know what you find.

Could you please clarify something for me? You said it occurs in park and neutral, but then you said it still occured when you shut off the engine while driving. This is not possible.

Take care,
-Chris

To clarify, I said earlier that I turned the ignition off while the car was running....I was driving down the road and I turned the key backwards to the off position and the car still had vibrations between the same rpm range.

Well, that's where you're confusing me. Unless you're driving a diesel, when you turn the ignition off, the engine stops running. If the engine stopped, but the car was rolling, and the vibration was still there, then it can't be engine related. That leaves the rolling chassis, up to and including the driveshaft and transmission output shaft. You also said the vibration occurs when parked. The problem is that when you are parked, the rolling chassis, up to and including the driveshaft and the transmission output shaft, are not moving, and couldn't be a cause.

This is where it becomes a paradox. What am I misunderstanding?

Take care,
-Chris

My suggestions to check are:

1. transmission mount
2. torque converter/flexplate