The two most common problems are bending/breaking rods, spinning rod bearings and leaking oil.

Problem: Common cause: Common fix

Bending/breaking rods: Overreving on stock internals: Shotpeen or replace rods with aftermarket units.
Spun rod bearing: Overreving on stock internals: Adapt B18C block girdle or add Z10 Engineering block girdle or similar.
Leaking oil: Improper VTEC oil feed port sealing: Reseal the VTEC oil supply port with a 1/8 NPT plug or welding.

If it is built right, it is every bit as stable as a B18C with a few CC's more displacement. If you still don't trust it, throw in a B18C crank and rods. That will take the R/S ratio from 1.54 to 1.58.