one should be thinner for the timing side by a couple of threads , the thread in the timing side hole in the crank should end where the oil feed hole to the big ends is. try the plug in that hole if you have a thin plug, or measure to the edge of the hole and measure the plug. I fully tightened a plug and marked it then put a groove in it to get maximum flow, you on about A10 my mistake thought you meant plugs , didn't read it correctly some person rattling my tabs about this bloody corona situation and effin dominic whatsit and just won't shut up, rant over, sorry