EL I6 motor - Problem :

loud noise like something hitting or gear teeth not meshing correctly
coming from top of motor, accelerates fine, power not affected noise starts at 3000 - 3200 rpm and on backing off -decelerating.

have had the top off twice, valve gear, timing chain and cog rockers and Camshaft look ok nothing loose, no obvious signs of wear, grooving, rubbing.

had compression test all ok.

injectors checked working fine.

motor is high compression speedway motor, raced it sat night ran hard runs ok made power didnt seem to affect output or performance.

blowing puffs of white smoke when the noise starts.

not a nice sound and something is causing it, but the mystery is not losing any power,

Ive heard it once before on a EB 4.0l anyone got any ideas what it could be short of tearing the motor down. the noise is not normal.

Is it sort of like a rattling noise? Could be timing chain slapping against a snapped guide. My old motor had a sort of rattling noise which can be heard at 2000RPM and was a nuisance. It was caused by a snapped timing chain guide, might be worth looking after before something bad happens.

phong =P~

Could have lost an Idler shaft bracket bolt.

or as Phongus said, guide may have snapped off and made a nice home down below.