ok my original block was shot so I had to pick up a good block from someone and it didn't have a crankshaft in it. Well I got what I thought was an lt1 crank from someone else and just got my motor machined and assembled back from the machine shop. I just realized that I can't install my crank hub because my crankshaft has a key on it. DOes this mean I need to run an older style fluid damper, what about my flywheel? can I run the lt1 flywheel or do I need a different one. This majorly sucks, please help. thanks

 

All LT1 crankshafts have a keyway milled into them from the factory. There just isn't any key. If the crank you have has a key stuck in it, just remove the key.

 

ok I got the key removed no problem. My main concern was that I thought lt1's are internally balanced and if I use this crankshaft that I don't think is from an lt1, wont it be off balance if I dont use a keyed damper and just use the stock lt1 crank pulley?

 

LT1's are neutral balanced on the front (damper) and externally balanced on the back end. They are not internally balanced. A Gen 1 crank will work, but you have to balance the entire assembly since the factory Gen 1 cranks are balanced for heavier pistons.

 

I imagine if you don't get it balanced than it will vibrate?

 

If its a stock LT1 crank, and you are using it with stock LT1 rods and pistons, its not going to be a perfect balace, but it won't be far off. If its a stock Gen 1 SBC crank, the entire rotating assembly needs to be balanced, or its going to shake.

 

Yeah itsa tricky situation there as most all aftermarkets say that the stuff is internally balanced. The truth of the matter is any one piece seal will work as Injuneer correctly responded.
It is well worth the few extra dimes to have any rotating assembly balanced. You free up some hp by doing so and also greatly extend the life of the engine. I have seen one put together unbalanced, fired up and broke in less than a minute. It was one of those I told ya so moments