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914World.com _ 914World Garage _ Carbs vs Altitude

Posted by: Headrage Dec 3 2005, 10:30 AM

I know it's really not that important to me right know being that my car is sitting in someone else's garage but WHEN I get it back and completely dialed in, at what altitude do carbs start complaining?

Posted by: SLITS Dec 3 2005, 10:35 AM

They don't complain....they jes get fat

And I doubt that you are going to stop and change jets to run above 5000'

On second thought, you could install a mixture control knob like on aircraft with some "minor" modifications to your Webers

Or maybe you could borrow Britt's Barometric compensator

Hi Allan & Good Morning

Posted by: Headrage Dec 3 2005, 10:37 AM

So 5000' is the number?

Posted by: SLITS Dec 3 2005, 10:42 AM

Each 1000' of altitude will induce minor varations.....5000' is a good number to me as the varations are cumulative.

When taking off from a high altitude airport, it was common to run the mixture control for max power......

Now that that's said.....altitude is not the only factor...temperature, humidity, etc are also factors

Posted by: SpecialK Dec 3 2005, 11:15 AM

I remember driving from San Diego, to Denver. Car (not a porsche) got progressively worse, but "hit a wall" at around 8000'. Felt like I was pulling a 5th-wheel!

Posted by: Gint Dec 3 2005, 04:03 PM

This I can speak to from experience. I've driven my fair share of cars (carbuerated mostly) from the west coast to Denver. With carb'd cars, I always can feel a noticeable difference as soon as I hit 4000 feet. Around 10k+ you don't want to stop 'cause some cars can be a PITA to get the car started again. They will start, but takes some cranking. When I have to stop at that kind of altitude, I like to park downhill so I can roll start if need be. Now all of that is moot if you rejet as soon as you get to altitude.

Posted by: Flat VW Dec 3 2005, 04:18 PM

QUOTE (Gint @ Dec 3 2005, 02:03 PM)
This I can speak to from experience. I've driven my fair share of cars (carbuerated mostly) from the west coast to Denver. With carb'd cars, I always can feel a noticeable difference as soon as I hit 4000 feet. And yes, around 10k+ you don't want to stop 'cause some cars can be a PITA to get the car started again. They will start, but takes some cranking. When I have to stop at that kind of altitude, I like to park downhill so I can roll start if need be. Now all of that is moot if you rejet as soon as you get to altitude.

The other variable for me on the way to the Fall Foliage Classic ,at least, was that the car was packed to the gills.

I bet the car gained 300 lbs. in just cargo, plus a full tank of gas, etc.

I "pulled" my first mountian at about 4000' elevation, and I thought I might just cry, the power was so diminished.

Once I got to approx. 2,000' elevation, it was not near as noticable.

John