quick balance question

[70 500]

I'm lookin at buyin another toy to play with other than my charger. It's an 86 Camaro with a small block 350. When i test drove it there was a bad shake when i hit about 80. it supposedly has been realigned and the tires are new plus i checked out the steering and suspension in the front. all the ball joints and shafts loook good. could this be because the small block is internally balanced and a different flywheel was put on? lemme know if ya have any ideas, no big deal really im just gonna buy it to beat the hell out of.

[Charger-Bodie]

Its impossible to balance a 350 thats for or in an 86 camaro so you must walk, no run away as fast as you can   Just kidin ....it could really be a number of things such as drivshaft balance, exhaust , engine or tranny mount , plus others ...and by the way vibrations can be very tricky to track down and costly so be sure to take that into consideration!

[BrianShaughnessy]

86 Camaro's didn't have 350's available *(except for a few select IROCs).  For all intensive purposes, let's assume this isn't one of these.    Therefore your motor was swapped.  While some might think it's an engine balance problem being possibly due to a 1 pc rear main motor car/trans being swapped with a 2 pc motor or some bad combo of either,  I'd tend to think that these would be more noticeable at lower speeds than 80.   You don't say if it's a stick or a auto.   You don't state your diff ratio either.   I'll assume 2.73 as it's a common ratio and would tend to move driveshaft issues to a higher speed range - like about 80.

The rear trans mounts take a beating in these cars but they tend to show up after letting off the gas.  And the cheap stock driveshafts tend to get wobbly after awhile... if they were ever straight to begin with.   

[70 500]

i know the motor has been swapped, he junked the 305 and put in the 350 15,000 miles ago, i didnt check any u joints out, and it is an automatic with what tranny i dont know