Merc 3.0L Jets for varing altitude 3500'-8000'

Sparks75

Cadet
Joined
Jun 1, 2010
Messages
6
I am currently running the stock 145 jets in my 1989 3.0L merc 15P 4 blade prop, there is a little bogging...
I'd like to change the 145s out for Merc recommended 140's for altitude between 5000'-9000', which will cover most of my needs, chatfield ~6000, Steamboat lake ~7000, green mountain res ~7500., dillon, etc etc
But what about when I go to Macounaghy which is I believe about 3400' will I need to change the jets back in order to keep from running too lean and burning a piston?
or is that not enough altitude change create a problem?
I hope to put the 140's in leave them alone.
Any other altitude tweaks?
I hear advancing the timing also helps...
thanks the help
 

Sparks75

Cadet
Joined
Jun 1, 2010
Messages
6
Re: Merc 3.0L Jets for varing altitude 3500'-8000'

Not sure if it is relavant, but I am also installing the following ignition this week components:
PerTronix Ignitor II
Flamethrower II Coil
So spark should be hot and burning clean
 
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