98 Altima's timing was found to be about 20 degrees past spec. Distributor
adjustment allowed only about 15 degrees correction. Conclusion was that
one of the timing chains jumped a tooth. Made the adjustment and ran the
car less than 100 miles. Performance was just OK, then one day car would
not start at all. Conclusion is that the chain jumped another tooth.
My question is: Does anyone know how many degrees past spec can the engine survive before risking valve-piston interference? Also, is valve-piston interference always a LOUD event, or could it also have happened silently.
Bottom line: What are the odds that valve-piston-head damage has occurred?
If you are correct in your assumption that the timing has jumped a total of two teeth, you're probably aleady experiencing valve to piston contact. At this point do turn the engine over anymore, although the damage if there is any, is already done.
I'm a little confused on this. Did someone decide the belt had cogged a tooth on the exhaust side ( I assume the dizzy is driven of the exhaust cam) and merely maxed out the dizzy advance then sent you on your way?