I have had this bad vibration ever since i put my new engine in. It is a 355 built by ls1speed and the only things I installed on it was the intake manifold, oil pump and pan, then I installed the engine. The whole car shakes really bad all of the time! Could it be bad motor mounts? Or could it be that something was assembled wrong in the engine? I don't know what to do, Any suggestions?

 

is it cammed?

 

driveshaft? unbalaned flywheel?

 

A4? Did they internaly balance it? then put the stock flex plate on?

 

flexplate or motor mounts most likely

 

Yes its cammed and it's an A4. It's not the driveshaft cuz it shakes just sitting there. The engine is internally ballanced. I forgot to mention that I also installed the stock flexplate when I got the engine, Should I have had it balanced??? Nobody told me to do anything like that. Thanks for your help guys!

 

thats your problem, take the weight off the flex plate or get a unbalanced flex plate.

 

So that would do it huh? Is that hard to take the weight off? Do you think anything would be harmed from this vibration?

 

that, and also did they do poly motor mounts? those tend to make the car vibrate

 

No, I still have the stock ones on.

 

There was a thread on her not too long ago were the same thing happened to some one else, and he did do damage too his I believe. Im not sure it there hard to get off or not. You might want to look into buying a unbalance flexplate.

 

K, thanks! I'll check into it.

 

Summit has SFI-rated flexplates for internally balanced motors for a very good price.

Does the LT1/LT4 have a specially weighted harmonic balancer or front pulley as well?

Jim