You could try running some Nulon lifter free through it for about 1000-1500kms then do an oil change using the oil of your choice. Putting some engine oil flush before you drop the oil probably isnt a bad idea if you think its been neglected a bit servicing wise
Yeah, i tried the nulon lifter free and it quietened down a fair bit. now i can drive on the motorway for about 20 minutes before it comes back then goes again and comes back. Yeah, and i'm going to try an oil flush and another oil change and i might have to do this a couple of times i think, as i'm just about to do a big cam and double row timing chain and bigger valve springs but really dont want to take the heads off at this stage to do the lifters. So i hope it works.