Hello all. So ive been doing a minor restoration on my GN. its ben sitting since February with only a handful of startups. So I am finally all done with the paint/bodywork and I have a slight knock at startup. Only does it after sttting for 30 minutes or more does not make any noise after engine is running. Its a very distinctive knock....maybe 4-5 times. What are the chances its a lifter leaking down(fingers crossed) Am I correct in assuming this since it doesn't make the noise at all after the is running? Its kind of hard for me to diagnose as I have to let it sit and it only knocks for a second.