can you replace one main bearing cap without line boring

[BigBlocksRule]

Take it to your machine shop, most have buckets of caps that have been salvaged off of old blocks. Mine took the time to check several, ended up with one that was a dead-on fit. Saved me some money for sure!

And if you're watching Horsepower TV to learn how to build one, DON'T!!! I cringe every time I see those guys smacking main caps down into the registers with a hammer. You're applying what amounts to reverse direction detonation when you do that. Snug 'em down, then tighten the bolts to get the cap to snap down into the registers.

[russgt]

Lightly taping the cap with a hammer will ensure that the cap has properly seated, preventing what happened here, tightening down a cap and it breaking because it was not sitting flat on the block.