VolvoPenta 7.4l Carb Rejetting Altitude

[bruceb58]

Now that my boat is permanently at 6,200 feet in Lake Tahoe, thinking about rejetting. Reading that I need to drop 1 size jet for every 2,000 feet. My plan was to just pull the jets, see what number all 4 are and reduce by 3 on each one of them.

Any flaw in doing it that way or should I do a plug read with what I have to see if I really need it? Boat runs fine except its a little cold blooded while warming up. I need to adjust the idle mixture and have the choke pull off sooner for that.

 

[alldodge]

should I do a plug read with what I have to see if I really need it?

No expert, but I would do the plug read, and drop size a bit slower

 

[bruceb58]

No expert, but I would do the plug read, and drop size a bit slower

My plan was to do it this off season anyway. Next time I am up at the lake I will try to do a plug read.

I wonder if the secondaries are even open at 3000RPM. My plan was to run at 3000 RPM and immediately stop the boat and do the read without letting it idle at all. Maybe I will have to do a second run at high RPM so the secondaries are open.

When I rejetted my Harley, I just bought a bought a few jets and changed them out one at a time until my plug read was good.