recently had a used motor put in my 89 CRX Si, since i hydrolocked the last one...

since i've driven it with the new motor, i've noticed that it sometimes blows gray/black smoke above 4-5000rpm when i gas it. and will sometimes smoke around 2-3000rpm when cruising. its not a thick cloud of smoke, just smokes for a second or two. so i checked the cap, rotor, and plugs. and this was what i found:
cracks and arcing all around the inside of the cap, worn, black and crusty spark plugs, everything looks original, same goes for the o2 sensor.

would the faulty ignition cause the smoke?

 

cracked cap can cause hydrocarbon's. blackish smoke coming out the exhaust is fuel, grayish smoke coming out of there is water, blue would be oil. try replacing the cap, plugs, and wires like you were going to do and post back.

 

for sure!

 

ok, so i replaced:
o2 sensor
pcv
cap
rotor
plugs
wires
fuel filter

runs alot smoother now with better pick-up. but, still smoking black at high rpm, above 4500rpm. it's not a huge cloud of smoke, just a little bit. actually better than before the tune-up. but i can notice it from the sideview mirror and standing at the rear of the vehicle. smells like fuel also.

so is it normal to burn rich while gassing it? or do i have other problems? any suggestions would help! thx in advance