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High Altitude adjustments

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R

RonR

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Folks,

I will be heading up to higher altitudes later in September to participate in Driving for Kids, a fund raising event for a free Colorado camp for children with life threatening illnesses, one of several in the U.S. started by Paul Newman.

Our round trip driving route of 2000 miles, will vary from our origination point of 900 feet elevation in Kansas City, Missouri, to around 5700 feet, and at some point, around 10,000 feet to get across the Rocky Mountains.

I can’t remember what adjustments are needed on my 1959 Healey 3000 to compensate for the higher altitude.
Is it the fuel/air mixture, or the timing, or both?
What specific changes should I make once I reach, say, Denver at elevation 5280 feet?
If it is the timing, does anyone know the relationship to one click of the distributor adjustment knob and degrees?

Thanks.
Ron

p.s. Feel free to private message me if you are interested in supporting the Camp through this event.
 
I've driven over the Sierra Nevada and Rockies in my BJ8 many times. If necessary--not always--I'll open the slow run valves a half turn or so and lean it out a quarter turn or so (just remember what you've done so you can reverse the changes without having to fully re-tune the carbs). A '59 would have, let's see, HS6 carbs, maybe? It's a bit more of a pain to fiddle with those, you'd want to open the throttle stops, and lean by 3 flats or so. Truth be told, I think you probably won't need to mess with the mixture at all for one high pass, unless the engine bogs down a lot and blows black smoke, so just opening up the throttles a little at idle may be all you need (if that). SUs are to some extent 'altitude compensating.'
 
In 1992 for Conclave I adjusted the carbs on the BJ8 in Pueblo, the car had been tuned before we left, and it ran terrible the whole time I was there and when I returned when I had 'reversed' what I did in Pueblo. I don't remember exactly what I had done. In 2002 for Open Roads in Lake Tahoe in the 62 Tri-Carb I didn't touch a thing after we left St. Louis and it ran great the whole time. I'd leave it alone until it told you it wanted something changed.
 
I live in Tahoe at 6500 ft. I'd advise leaving it alone. You are not going that high. If going higher, you have less molecules in the air so you will be running rich. But years of experience have taught me to leave it alone and live with the slight back firing when I travel to lower altitude when I take the foot off the gas pedal.
 
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