Advance or Retard

[Fired Up]

Taking my ski boat on a trip this summer. The Lake sits at 5000' elevation in Nevada. I know you lose HP with the elevation. Do you Advance or
Retard the timing to correct for this. This is a standard 185hp V-6 Chevy I/O, Carbureted.

[LakesOnly]

Uh, well, you should really adjust your fuel mixture/jetting in order to compensate for this.
If the air up there where you will be running the boat is thinner, then the result will be a richer mixture. So theoretically you could run more ignition timing advance at altitude w/o detonation (all else being the same). But the problem is ultimately with your air/fuel ratio.
LO

[Fiat48]

You'll lose about 20% in power just for the loss of air. You're fuel mixture will account for additional loss. With the type of motor you have, I'd say leave it alone. Enjoy the scenery.

[GofastRacer]

Fiat's right leave the timing alone, if you're jetted for around sea level, it will be slugish and you might want to lean it out some but if it runs good the way it is, forget it and have fun!. You know the saying! "If it works don't fix it"..

[Fired Up]

Thanks for the response guys. I think I'll leave well enough alone and carry an extra set of plugs in case they load up.

[Outnumbered]

I run my boat at both the river and at Lake Arrowhead (5,100 ft). The only thing I do is adjust the idle and prop down 2 pitch at altitude if I really want to pull. Sometimes I get lazy and leave the river prop on and it does fine, just a little slower out of the hole. No worries unless your set-up is already running rich. Good luck.
OL

[Fiat48]

He's right on the prop. Forgot about that. Really helps if you have a smaller pitch prop to put on for the trip.