On Jul 24, 2:20*am, Tim wrote:
On Jul 23, 5:56 pm, Vic Smith wrote:





On Wed, 23 Jul 2008 15:46:59 -0400, "Jim" wrote:

Salt water in the valve guides.
Rebuilders won't touch heads from sal****er boats.

That sort of cuts down your options, don't it?
But why is that? *I can see how the SW cooled heads might have
more of the passages eaten away, but they could grind, revalve,
respring, and reguide with no problem. *Just make it clear future
cracks aren't warranteed, same as any head rebuild.
Anyway, I'm only batting .500 with shop work on heads.
I don't know anything about those boat engine manifolds, but I guess
that's how the salt got in the guides.
The other thing that doesn't make sense to me is how the piston hit
the valve, because I thought that engine was non-interference.
Couldn't find that's a fact anywhere though, so maybe I'm missing
something.
Seems like there's big differences between car and boat engines.
Think I'll get an O/B.

--Vic

Well, one thing is that engine heads are sort of a soft cast iron and
after years of salt water exposure, the minerals of said water
actually impregnate into the heads and cause the cast iron to break
down. just like an old rusty iron water pipe that's laid bare to the
elements over several years.

So quality machine work is next to impossible- Hide quoted text -

- Show quoted text -

Sounds a bit like an urban legend. Guides are either knurled or bored
and inserts added. Knurled is quick and easy but won't last as long.
The salt water is not really going to affect either option. The seats
are hardened. Have been ever since they went to unleaded gas.
Besides, how does the machine shop know where the head has been
anyway?

As someone else mentioned, I too thought this engine was supposed to
be non-interfering. The other 305s I've seen from the boating world
have had seriously dished pistons, no way a valve would hit them. We
need more facts from the autopsy after the head is removed :-) I'd
also suggest removing a few other springs and checking those valves
for wobble.