Adjusting for Altitude

[tomelenbaas]

At what altitude will the carb need adjusting? (1988 Mariah - PCM 351). I normally use my boat anywhere from sea level to about 2000 feet. This summer we're going to Lake Almanor at an elevation of 4500 feet. Will it be necessary to adjust the air/fuel mixture? Thanks.

[Stoked]

I have a comp, same engine. I used to take it up to Almanor quite a bit. I never noticed a need to adjust for the altitude between there and running it on some of the lakes down in the Bay Area.