Disconcerting valve clatter or ping!!

[helm]

Does it only ping when the car is first started? It probably goes away after normal easy driving, and returns when you drive it hard? This is typical of the M50 it seems, It's hard to say how bad your clattering is compared to most. Try finding an auto zone and getting the Lucas Oil Stabilizer (synthetic type) and try it in place of a quart next oil change, hot conditions use 15w50 synthetic if that's what you're using, Mobil1 for 15w50 or Castrol 20w50 synthetic. That pretty much eliminated the noise in my M50.

Usually after a down shift or low rpms, accelerating lightly at low rpms.

[Bill R.]

knock sensors to retard the timing if knock is detected. I would first try buying premium from a different gas station than you normally do.. Has this only been happening in the summer time? Is your gasoline a blend for pollution reasons such as 10% alcholol or mtbe or any other additives which could lean it out?

Usually after a down shift or low rpms, accelerating lightly at low rpms.

[helm]

knock sensors to retard the timing if knock is detected. I would first try buying premium from a different gas station than you normally do.. Has this only been happening in the summer time? Is your gasoline a blend for pollution reasons such as 10% alcholol or mtbe or any other additives which could lean it out?

I had a valve job done, replace the exhaust values about 2 years ago! New cam chains and tensioner. I also have what sounds like a noisy lifter especially in the winter when it is really cold (minus 20C).
There is 138K miles on the 91 M50! Should be good for lots more.
thanks bill I'm also reading the other threads to which you have contributed.