Q: what is the timing for this car on 1990 Oldsmobile 88

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
car won't start back firers to air filter
(3) Answers
The spark timing on your 1990 Oldsmobile 88 is not adjustable. It sounds as if the timing chain may have jumped. Perhaps a compression check would be in order.
Any lean run condition can cause the engine to back fire through the intake. May want to have fuel pressure checked and mass air flow sensor for damage after backfire.