Reply With QuoteDon't hold me to it but I think the rule is one jet size leaner for every 2000ft. I know you need to run the carb leaner at higher altitudes because there's less air. I never had to deal with it cause I lived at sea level. Anyone else know the rule?
What adjustments should be done with timing and carburetion for high altitude water? I'm running on water that ranges from 4200 to 6500 elevation.
Don't hold me to it but I think the rule is one jet size leaner for every 2000ft. I know you need to run the carb leaner at higher altitudes because there's less air. I never had to deal with it cause I lived at sea level. Anyone else know the rule?
I would go down one jet size ,run run the boat to operating temperature.Shut the engine off and check plug colour.Run jet size down incrementally until you achieve a light tan colour.Jetting down starts around 1300-1500 feet above sealevel.
[This message has been edited by spectras only (edited July 16, 2001).]
Holley Carburetors & Manifolds book says go 1 main jet size down for every 2000' up. The same for every 40*F in temp up. It's assumed that there is a 4% change in fuel flow between jet sizes.
We keep my buddy's boat in the Penticton area [1320 feet above sealevel]in the summer,and I go down one jetsize in his 850 Holley on the 460 to achive the right plug colour.Don't notice any performance change at all at that altitude!
I say put a blower on it and not have to worry about altitude ever again! That's just me though.
Thanks Guys,
I have also heard that the timing should be advanced 4 degrees or so for every 2000 feet, any comments on this? Also I think that my Carb is an "ASE" brand or something like that, does this sound correct? If so were do I buy the jets for this carb?
even with a blower you have to back up 2% of overdrive for every 2000 ft, carbs are easy try a constant flow system on nitro or alky , even a constant floww on gas can give you fits
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