Ok, after more investigation I’m pretty certain it is tappet noise. It’s definitely at the top of the engine. I’ve checked the pushrods rotate which they do although some rotate more than others. Is this normal? I.e some spin fast in same direction , others spin slow and spin both directions. Either way they move.
There is plenty of oil getting to the top. I tried a 2thou feeler gauge in between each rocker pad and it made no difference. I’m leaning towards the fact the rocker shaft is worn and maybe the rocker pads. I looked at the rockers hitting the valve and a couple of them seem to move side to side when the are bouncing which I can only assume is wear in the shaft? Or is this normal?
Another thing I’m thinking is that it is worse on a warm day. I.e the oil is thinner making the noise sound worse? I don’t run an oil cooler as was told modern oils (valvoline vr1) don’t warrant it. I also run a sump guard but I’ve taken that off for now and next time we have a warm day I’m going to see if it is any different……