I just rebuilt the motor in my 91 crx (d16a6 block with z6 head) nothing in the motor is stock... the car was running good up to about 5k rpm because of low compression with no turbo. i tore down to bottom end and replaced the main cap berring (mains and rod berrings where plastiguaged and checked out good) i put the bottom end back together and about a week later it started knocking. I pulled the oil pan and mains and everything still seems to be in spec... the sound is coming from the #1 cillinder but I dont know where exactly... any ideas why it would randomly start this or what it could be?

.... I adjusted the valves and later double checked them about 2 weeks later...

 

usually if its nocking like that, its going to be the rods (bearings) but check it to see if any metal shavings are at the bottom of the oil pan

 

the rod berrings are fine and i didnt find anything in the oil pan... im woundering if is is a valve slapping because it only ticks on one stroke (either up or down) its driving me nuts