Motor shut down

" Chevy 283 in an older Chris

" Chevy 283 in an older Chris Craft shuts down at odd times while under power at speed.Starts right up again and powers up fine. This happens once or twice during a 30 minute run but not each time out. Checked for lose wire connections and replaced the points, rotor and condenser without solving the problem. Any ideas? "

" I have the same motors in my

" I have the same motors in my 67CC,completely check out the fuel system from tank to carb. "

" Jim,
Older boats, or old

" Jim,
Older boats, or older cars for that matter, sometimes have that happen because of a worn out ignition switch. Mostly ignition switches on boats are standard and not expensive. I recommend replacing ignition switches in older boats routinely after 15 or 20 years even without any problems. When you install the new switch be sure that the drain hole in the cylinder is pointed down.
Although hard to diagnose coils that are going bad tend to act up as the engine warms up and tends to cause a misfire at higher rpm's.
Check the connection of the ground cable to the engine. Make sure there is a clean contact there.
Eddie "

" Jim,
Mrpops makes a goo

" Jim,
Mrpops makes a good point. A quick check would be to loosen the fuel filler cap when that happens. You might have a clogged fuel vent causing a vacuum to occure as the fuel goes down. Loosening the cap will break the vacuum.
Eddie "

" jim,
only thing i could add

" jim,
only thing i could add is if ignition switch and all other ignition components are replaced and vent is checked is to look very close at the carb. could be float, needle and seat, etc. could be vent in the float bowl not working when engine gets hotter. its dying when there is a high demand for fuel. i'm assuming you have a mechanical fuel pump, which would rule out an external electric pump getting hot. you may even be able to find an inductive spark tester to put on the plugs when the engine is warm to see if it is ignition problem. "