Thanks for the input guys, he's gonna change the plugs to NGK for now and see what happens. I doubt it's carbon, it's been doing it for way too long now. It's not octane, he's used a higher rating and still the pinging is there.
Maybe it wasnt hydraulic lifters that was replaced, something was though.
And yes it's pinging, he's been doing his own work for over 30 years now on cars, he knows what pinging is, I heard it, sounded like pinging to me, a mechanic friend heard it, heard like pinging to him too.
