Ticking Time Bomb

Just started a ’72 Coronet 318.
It has been sitting for a number of years in
storage. Sounds like it may have a lifter that
has not pumped up, tic,tic,tic… Any ideas?

Add a quart of Marvel Mystery Oil and
hold the revs at 2,000-2,500 rpm or so, this
might take quite a while. No promises!
Assuming it quiets down, change the oil
and filter before driving it.
Worst case, is possible to diagnose
which tappet is bad (by feeling the rockers
at idle) and swap it with the manifold still
installed (factory tool C-4129 or a strong
magnetic pickup tool).