So.... on a 454 fairly stock with a 750 Holley DP how many jet sizes (Pri and Sec) do you jet it down going from sea level to 4,400 ft (Lake Powell). Budies boat runs rich there, fat especially at idle/low rpm. Any ideas out there? THANKS!!
Here in Reno...which is 4400 ft static elevation...we usually go down 2 jet numbers on primarys...leave secondary's alone. Lean idle screws for here. However if this is just an occasional trip....I would leave it alone and just lean the idle. Youll be a little fat but no big deal. You lose power with less air anyway.
Powell isn't that high either... I think full lake elevation is like 3700 feet, and it's considerably down from there... of course the heat drives up the density altitude so the engine thinks it's running at a higher elevation.
I agree with Fiat if it's just a once a summer trip...
Contrary to popular belief carburators do not need to be altitude adjusted. Since a carb is nothing more than a device that adds fuel [via atmospheric pressure] to a measured amount of air and its movement it will "self compensate" for less air by mixing less fuel. If your carb goes rich at only 4000' altitude then it is too rich to begin with or there is something else wrong with it. I have driven carbed equipped cars to 10,000+ feet elevation and the only problem I experenced is a noticable lack of power due to a severe lack of air. The engine did not show any signs of being rich by puking black smoke due to an excessivly rich mixture. Rhier-Morrison did a very informitive article in Natl' Dragster on this subject a few years back. I'm sure if you do a search on this you can find it.
Out of the Holley carb book. Holley carbs are calibrated for conditions at sea level and 70 degrees. As a rule of thumb in order to maintain the same air fuel calibration as was present at standard temperature and barometric pressure(70 degrees F and sea level) jet size should be dropped one number (or .002-inch) for each 35 degrees increase in temperature, or 2000ft increase in altitude. Also each time the altimeter is bumped by 3000ft power valve activation should be delayed by 1.5 to 2in due to reduced engine vacuum. Hope this helps. :idea:
Contrary to popular belief carburators do not need to be altitude adjusted. Since a carb is nothing more than a device that adds fuel [via atmospheric pressure] to a measured amount of air and its movement it will "self compensate" for less air by mixing less fuel. If your carb goes rich at only 4000' altitude then it is too rich to begin with or there is something else wrong with it. I have driven carbed equipped cars to 10,000+ feet elevation and the only problem I experenced is a noticable lack of power due to a severe lack of air. The engine did not show any signs of being rich by puking black smoke due to an excessivly rich mixture. Rhier-Morrison did a very informitive article in Natl' Dragster on this subject a few years back. I'm sure if you do a search on this you can find it.
you talking about your boat motor or the diesel in old blue?
you talking about your boat motor or the diesel in old blue?
No diesel engines here.....just gasoline engines....Ford gasoline engines in cars to be exact. :crossx: BTW, That article I was using as an example were from your heros Rhier & Morrison, die hard Chevy guys.....see I do listen to other people besides Ford people. :jawdrop:
have you read on bob glidden?lol..sox,bill elliot..what other ford dominated..lets keep this thread going......bob you going to modesto res tomorrow?
bob you going to modesto res tomorrow? Nope....I got to play last weekend at Berryessa....got work to do this weekend.
have you read on bob glidden?lol..sox,bill elliot..what other ford dominated..lets keep this thread going......bob you going to modesto res tomorrow?
i missed seein that avatar pics! where can we see the whole thing!
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