vibration

[JROBINSON1016]

hi guys,i m having a problem with a vibration,don t know what it is.i ve had this problem since i ve had my car.its not drivetrain,its definitely in the engine.if its idling i can rev it to bout 1.5-2 grand & feel it,when i m going down the road i can put it in neutral & feel it,at 2 grand.it feels like a lope,kinda like somethings out of balance.the car runs great,performance is excellent.has new jasper tranny,new u joints ,fresh rebuilt rear end,but it did it even before all this work.the motor had been rebuilt,stock ,it had like 25,000 miles on it,have receipts,now has like 30,000 miles on it.thot it might be dirty fuel injectors,but no luck with that.seems to have a little more lope to the vibration when it is cold.at higher rpms it tends to like smooth out.i have no idea,please help!

[wnmech]

Did you try unhooking the serpentine belt then start the engine and see if the vibration goes away. It could possibly be the harmonic balancer or one of the engine attached accessories giving you that feeling. Possibly an exhaust pipe touching a part of the frame.

[JROBINSON1016]

no,i haven't unhooked the serpentine,i will do that though.i don t believe it's the exhaust,it feels like it's something in the motor out of balance.i have read some of the posts on here,people talking about the balancer,that there is no keyway to align it with.although,if its not a balanced piece(no counter weight on it)i don t really see how that could be a problem.she still runs like a scalded dog,but need to locate the problem.any other ideas?

[Hi-Po]

Edit: it is probaly a mount of some sort. like mrr23 said. Could be a tuff one to figure out.

[mrr23]

check to see if there is a poly trans mount.

[JROBINSON1016]

i pulled the plugs,had ac iridiums,gapped at .035.i called a parts house to verify the correct plugs,they were,they said to gap them at .040,i think factory was .050.i gapped them at .040, cause it wasn t a big jump.seemed to help,still a little bit of vibration though,nothing like it was,any ideas on the gap for the ac iridiums?should i go to .050,or do the iridium plugs not need to go that far(.050)the plugs looked great,course they should be new since the engine had been gone through not too long ago.