2.5L YJ running rich... big time.

hey guys, i know this isn't necessarily XJ tech, but then again this isn't pirate, so i figured i could get some legit help...

we replaced the long block in this YJ with a TJ block, got everything connected back... it runs now, just rich. we messed around with timing a bit, and it seems to run too good to be way off on timing. we basically turned the motor to about 9 degrees, checked the cap and moved it to fire on number one cylinder. the timing is not adjustable, evidently. but could the distributor be one tooth off? i'm at a loss as to how it could be, the rotor is pointed exactly at number one cylinder at 9 degrees.

sorry, i'm not much of an engine guy...

If your talking 9 degrees BTDC, you should be good. Before top dead center, not after. What about 02 sensors?

yeah we're 9 degrees below. that's our next step is the 02 sensor. what would be the best way to test it?