4spd swap problem

[340 swing]

I recently replaced my 727 auto for a A833 4spd hated driving the auto. So everything works as it should. But I have a vibration that was never there before. I rebuilt the transmission not my first time. New driveshaft custom made with new yoke and joints. The issue happens when I I drive or even sitting in driveway not moving just rev it up. It has a 360 that I had a b&m flex plate no vibration. The flywheel was balanced with clutch cover bolted to it. My question is internal vs external balance did I do something wrong Or am I going in the wrong direction here.

 

[Marcohotrod]

In driveway is engine balance. 360 is external balance. You need the rare 360 weighted flywheel or

 

[340 swing]

In driveway is engine balance. 360 is external balance. You need the rare 360 weighted flywheel or

Thanks for the reply I figured that was the issue. Luckily I’m building a 340 just wanted to get the car running before the engine was done to work out any bugs. Will it hurt anything if I drive it or just annoying

 

[rklein383]

Not all 340's are internally balanced. Make sure you discuss with your machinist.

 

[340 swing]

Not all 340's are internally balanced. Make sure you discuss with your machinist.

Already did it had the rotating assembly balanced wit this flywheel and clutch but I figured while I wait I would put 4spd in to work out all the clearance issues and bugs