I have 1957 a six cylinder Gray which is making a clanking noise at the
bottom of the second cylinder. I wonder what I might expect to be the
problem

When we pull the plug wire the noise dissipates. I get 750 compression on
all cylinders but this one is 550. I checked the lifters and springs which
appear to be fine. Not being familiar with motors I am unsure of what to
expect when I find a mechanic who can visit my boat. Can anyone give me
their best guess as to what would make a clunking sound or backfiring
sound..
--
Doug