Ok, I just got done putting my new 383 in the car. When starting it and revving it around 1800 and higher it gets a vibration in the WHOLE car. The shifter and body vibrate bad. It's almost like the car has a miss to it. I've already diagnosed a few things and here are my conclusions.

All spark plug wires are plugged in correctly and they are firing like they should. (checked with timing light)

I doubt it is the rotating assembly. Balancer spins true as does the flywheel. And there is NO vibration in the motor. It sits still and you cannot feel the vibration in the motor when it is being revved.

The flywheel, balancer, and pressure plate were all balanced with the rotating assembly and being how picky the engine builder was, he got it damn near perfect.

There is nothing touching the body anywhere so that could not be the problem.

Now here is the weird part, when hooking up a fuel pressure gauge, the pressure stays around 40 PSI at start up and as you give it gas the fuel pressure DROPS. When the motor is around 2400 the pressure is at around 36 PSI.

My next steps are to change the coil, ICM and possibly the opti to see if that is the problem.

Could it be my fuel pump or pressure regulator ****ting out on me? The pump is a 255 LPH Walbro and I don't know how long it has been in the car.

ANY suggestions or help would be appreciated.

 

When my car did that it was from an improperly balanced flywheel. I know you said yours was balanced at the shop. Was the pilot bushing installed correctly as well?

 

I installed the pilot bushing with a socket and hammer. It went in fine and was flush.

 

Did you purchase a neutral balanced flywheel or keep the stocker?

 

It's the stocker.

 

The stocker flywheel will not work with that if the stroker kit you bought is a balanced one and most are. You will need a neutral balance flywheel.

 

The stroker kit was not balanced when I bought it. The engine builder balanced the rotating assembly with the flywheel and balancer.

 

I still suspect that the flywheel balance is the issue. I do hope it turns out to be something simple for you though. Good luck.

 

Thanks man.

Any other inputs?