what all would i need to do to change my '66 with a 2bolt main to a 4bolt for a crate engine? i dont plan on doing it myself, but just wondering whats parts i'd need to buy and what the cost of labor might be

Perhaps you don't fully understand what a 4 bolt main is? :confused: You see, a four bolt main means that the main caps the hold the crankshaft in have 4 bolts in each one. 2 bolt mains have 2 bolts in each. So if you were going to put a 4 bolt main crate engine into your 66 that currently has a 2 bolt main you would need to change nothing on the car. All you would need is the new motor. I'm not sure what labor to swap an engine would be. I hope this helps... If it doesn't then I guess I don't understand the question. :confused:

Most crate engines have 4 bolt mains, so when you buy the crate engine, just make sure it has 4 bolt mains.

And just to expand on what was said above... If you were anticipating ever actually "needing" 4-bolt mains, it would likely be far cheaper to just buy a crate engine that already had them, as opposed to buying a 2-bolt main engine and having it converted... Plus a 2-bolt crate motor is probably a non-performance replacement anyway...

Not sure on the cost of the labor, etc. but you would need to dissassemble the engine completely, install the new caps, drill the new holes for the additional bolts, then line-bore and hone the mains... clean and reassemble everything...