68 dart 360/904 vibration

[blue dart gaz]

hi all i live in the uk. last year i bought a 68 dart from san gabrielle pasadena ca. this car had a tricked up 360 with 904 trans and 3500 stall converter with sfi spec flex plate. the engine had spun a rod and when it arrived in the uk it had also froze up due to bad wether and cracked the block. sine then i sourced a 71 360 block and built a new motor using a eagle steel crank and eagle i beam rods je pistons comp cams 292 cam edelbrock performer rpm heads and intake etc etc
i have installed the engine and it has a vibratinon that clears at 3000 rpm this is a violent vibration from 1000 up to 3000
since running it it lost drive and broke the trans from the bellhousing and lost drive!!!
can any one shed some light on this situation please!

 

[Snake]

Misalignment were your tranny bolts up is my guess has it ever been aliened bored?

 

[zhandfull]

Did you internally balance the rotating assembly. I would think that would be required with the new rotating assembly. If it is internally balanced you may be mixing standard 360 externally balanced parts with your new internally balanced engine. Balancer, flex plate, convertor should all be neutral balanced with an internally balanced rotating assembly.

That would seem to make the most sense with the limited information provided. Sorry to hear about all the problems with your long distance purchase.

 

[blue dart gaz]

ive never line bored anything and i havent balanced anything either, with the trans broke off the engine still runs and vibrates but not as violent. i dont even know if it had the vibration before i owned it as i bought it a non runner,im guessing it did have the vibration. can anyone tell me what flex plate /torque converter combination i should be using with the 360 /904 trans thanks

 

[abodyjoe]

Flex plate for an externally balanced la360 and a neutral balance converter is the b&m 10239