Originally Posted by
Jim P
Negative is ATDC positive is BTDC. The rattle comprises of a couple things, rapid pressure spikes from combustion of fuel, fuel combustion too early in the compression stroke. If it?s too much fuel combusting way too early, the higher the engine load the higher the likelihood of catastrophic engine damage from large amounts of negative torque being imposed when trying hard to create positive torque. Lower engine speeds and lower engine loads is more permissible to it with damage to the engine. In fact, stock there are points in the cruise region of a stock 5.9 CR engine you can hear the rattle.
Lowering what for eliminating smoke depends on what is causing the smoke are where it?s causing smoke.