What are main caps? Can i buy main caps from a diffrent block and just put them on my block?

 

Main caps hold the crankshaft in place. I don't mean to sound harsh but if you don't know what they are why would you want to replace them?

 

Crankshaft main bearing caps hold one half of a metal bearing (the block holds the other half) for the crankshaft to spin on. They are line bored while installed in the block before assembly. If yours are not bad, you do not need new ones. New bearings maybe. If you have a bad cap, you can get caps off another block, but they will have to be line bored so everything runs true.

 

It is a bare block witout main caps....what tools will i need....what happends if its not line bored?

 

You will need to get caps and then have the assy line bored. If not they won't be truly round and your motor probably won't last too long.

 

You are not just boring for a round hole, you are also boring to make sure that everything (crankshaft) is going in a perfectly straight line through the bearings and caps. That is why they call it line boring. It is critical. That is why the caps have markings on them from the factory because they have only ONE position and direction in the engine. You cannot swap them between engines or even in the same engine without line-boring them.