garretttt

I rebuilt my 283, everything went back standard and purchased a rebuilt powerglide to put in it, it runs fine until you get to 50mph then there is a vibration in it, if i put it in neutral and coast its not there back in drive it is, any help would be appreciated, its a prettu good vibration which appears to be in the engine transmission area

plaidside

I would check to see at what RPM the vibration occurs and then with the car in park bring the RPM's up to that point and see if you have the same vibration.
The other possibility is the driveshaft angles are changing under a load.
Joe

steampunk c1

Check drive shaft uni joints for wear and maybe have the drive shaft balanced. I do rember reading something about the rear uni angle that may have been a cause of vibration as the angles are quite high.

garretttt

In neutral the engine starts vibration around 2000rpm and gets worse from there

Frankie the Fink

Here are a couple of articles I referred to a lot when troubleshooting a similar problem - my issue turned out to be an out-of-balance driveshaft

plaidside

This statement tells me your vibration is not caused by the drive train.
Disconnect the drive belt and try it again, if you still have the vibration then you have to do some digging.
When you rebuilt your 283 did you change pistons, crank or rods, has the engine been balanced, did you change the flywheel or clutch?
All these can cause an engine vibration.
Joe

K2

Another thing to check as you diagnose the problem is dynamic cylinder balance. Do a compression check to see if you have equal compression in each cylinder. If not, check valve adjustment or for possible flat cam. A weak cylinder becomes more pronounced as rpm increases.

6D2148

Put a vacuum gauge on it, that will help determine if it's an imbalance or a miss fire