Actually had motor/trans w/ a g.v. Od unit installed & rear done… got it back months later noticed motor was uneven.. loosen all mounts (trans too) & brackets, level motor retighten everything & w/in a week motor slides down again
Are you lifting the engine so everything is topped out ?
If so this is your first problem , you need to loosen the bolts and let it all drop into place and the only real adjustment is leveling side to side , you can't have the bolts holding the engine UP to give you needed clearance because the vibration is just going to let it all slide back down. Sounds like you need to clearance the header tube?
