Nissan Repair: Timing Chain Settings (D21-Hardbody-Nissan) 12V 2.4L, tdc mark, mark edge

Question

D21 Cam Sprocket Hi Calvin,  

Thanks for taking my question.  I have a '90 D21/12V 2.4L Hardbody pickup with a recently installed timing chain (guides, etc.).  It has run rough every since it came back from the shop (2-months).  Based on feedback (on-line and off),  I believe it's possible the chain is off "1" tooth.

Also, looks like they may have tried to compensate with the distributor adjustment.  She runs rough as I said, but also has started to backfire.  My guess it's starting to build porous carbon on the pistons causing the backfire.

My question: I've set #1 to TDC (compression),  The timing mark on the cam sprocket is one tooth higher than the 'head top' edge.  I seemed to remember seeing this once and the sprocket mark was even with the head top edge.  Can you confirm it's one tooth off its mark or offer alternative view?

Many Thanks,
Craig

Answer
Hi Craig -

You are correct. The sprocket should line up to the TDC mark edge of the head, rotor pointing exactly at #1 tower on the distributor, and the timing mark should be at TDC. All these have to line up exactly, or the vehicle will not run correctly. It cannot be compensated by turning the distributor.

I would take it back, and show them this photo.

Good job on the catch -

Hope this helps -
aloha
calvin