BoatBanter.com - View Single Post - Running a large gasoline engine at low RPM for long periods

trainfan1

wrote:
On Fri, 28 Sep 2007 13:29:04 -0700, Diego wrote:

I have a boat with twin 350 hp Crusader gas engines. I would like to
cruise this boat between Florida and the Bahamas. It will be optimal
for me to cross the Gulf Stream at high cruising speeds to get out of
harms way, then reduce to a very slow speed when moving around the
islands in order to conserve fuel and increase my range. I've heard
that this can cause fouling of spark plugs. Has anyone tried this and
can comment on doing something like this? Does the plug fouling
happen over a lengthy period of time (weeks) or rather quickly (hours)?

Any fairly modern engine will be fine going slow...

2 strokes have a
problem with this for a number of reasons but 4 strokes don't share
those problems.

Unless it's an E-Tec or Optimax.

A port or direct fuel injected inboard engine should do fine
indefinitely. A carbed or CFI engine may suffer from fuel pooling &
sporadic rich operation(fouling the plugs), especially high performance
engines. If intake charge velocity is maintained, by design or by
engine speed, prolonged idling should pose no problem.

A 350 hp Crusader should be a 454 Chevy(maybe 496 CID if newer), it
should do fine idling, even with carbs.

Rob