1990 Z auto 2plus2 non turbo 70 k miles. New long block from Orient engine installed with old injectors, heads etc. Valve issue with old engine so put in a new long block . Old engine ran ok after starting (starting was difficult esp in cold).
New engine running rich. Black smoke build up on rear bumper ,gas in oil after only a few miles. Replaced air filter, engine temp sensor. No improvement. As injectors were fine on old engine what might problem be.
Were they mishandeled during replacement or airbox or something else?
Appreciate any help.

There is several reasons you may be running rich. First thing would be to hook up to a scanner and see if there are any codes. I can tell you however if you have full in the oil your rings are bad or were not done correctly the first time. At no point should you have fuel in your oil.

Now my suggestion is to drop replacing parts you don't know are good or bad. That's just a waste of money. Diagnose and replace. It is difficult to diagnose without the right tools but it can be done. Some reasons for running rich can be bad injectors, bad o2's, faulty fpr, bad tune, bad sensors like tps (or improperly adjusted one), improperly adjusted CAS, vacuum leaks, bad maf sensor and the list goes on. That's why diagnosing the car is best.

First thing I would do is check and make sure all your sensor are set correctly and then go from there. However as I stated before all this...if you have fuel in the oil you have bigger problems then running rich.

I hope this helps.

thanks for the reply. I am suspect of the "new engine" from Orient Engine Ky. as they closed up soon after my delivery. The engine sounds like a washing machine and with the above described problems possibly sent a cleaned up POS.