I have a newley built stroker that I have a pretty bad vibration going on, I have the weighted harmonic balancer and the weight plate that goes between the crank and flexplate so it should be balance alright but I have installed a saginaw 4 speed and now there is vibration, I havent even had the chance to put it into gear cuz of the vibration.. I have also noticed there is weights on my crank pulley... is that normal or could that mess it up? The car sounds fine when at idle but if I give it even a little gas all hell breaks loose and it rattles and shakes pretty bad, enough to tell me not to run it anymore. It is bugging me and I dont know what else to do, Is there things im missing? doesnt sound like a misfire... motor mounts? please help!

 

Is your bell housing centered with your crank? You can get offset dowel pins to center the bell housing. Use a dial indicator to see if it's off or not. Since the vibration comes into play when the trans is installed.

 

is the trans the same one that was in it before? are all the parts new or original? if the balance is not correct it will vibrate more as rpms are increased. a bent trans shaft or misaligned flywheel may be the issue. can you see the flywheel when running. if so look to see if its wobbling or could use a mic an turn the crank and measure to see if its wobbling

 

I was curious if you had your flywheel balanced too.

 

I guess we will never know what the problem was.

 

...another one of life's great mysteries...

 

Did you put in a pilot bearing when you when to the 4 speed. Also with a new 400 style crank their need to be a dowl pin installed to correctly bolt on the flex plate or flywheel. This pin is centered between two bolt holes and must be their.