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#577022 - 05/17/09 12:48 AM Effect of elevation on carb tuning
Lin Offline

Gold Member
Jedi Warrior

Registered: 04/13/02
Posts: 572
Loc: Harrisonburg, VA
Sorry, I meant to ask in my post about Going Mobile:

What are the recommendations on adjustment to SUs for traveling at elevation. Mine are tuned for driving in Virginia at about 1000 ft. I am around 7,000 ft. now and anticipate that I may run into some problems tomorrow.

Lin
_________________________
1960 BT7 "The Bloody Beast"
1959 AN5 Bugeye

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#577030 - 05/17/09 02:12 AM Re: Effect of elevation on carb tuning [Re: Lin]
mikespain Offline
Jedi Hopeful

Registered: 09/03/06
Posts: 186
Loc: malaga spain
Hi,the air is "thinner"so mixture will tend to be richer,it depends how long you are going to be at that altitude,if the car has no noticeable running problems ,I would not bother to adjust anything,as to get optimum mixture you will be making adjustments every time you change altitude,it's better to be running a bit rich than too lean,better to have plugs a bit sooty than the possible engine damage and running hotter from being too lean.If really affecting running then lean the mixture out a bit on each carb

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#577032 - 05/17/09 03:35 AM Re: Effect of elevation on carb tuning [Re: Lin]
Keoke Offline

Silver Member
Yoda

Registered: 04/19/04
Posts: 7969
Loc: LosAngeles Calif.


Hi Lin, if you run into running problems first lean the carbs as has been stated. Real sluggish performance may require a slight timing adjustment too. However, I have run at 9000 Ft elevations and just suffered with the power loss until back at lower elevations., of course this running was not for a prolonged time.Cheers-Keoke
_________________________
Daimler V8 Saloon; Safely Fast, Built to Last & Smooth as Glass.

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#577085 - 05/17/09 10:53 AM Re: Effect of elevation on carb tuning [Re: Keoke]
HealeyPassion Offline
Jedi Hopeful

Registered: 01/08/09
Posts: 151
Loc: Colorado, USA
Or we (Ric and I) could hook you up with EFI which will do the adjusting for you :-).....

Seriously, it was great to meet the Going Mobile team yesterday! A caravan of beautiful cars out for a amazing tour!!!..what could be better. If you were running okay going over Moument pass on the way to my place (over 7,000 ft. running 75 mph) you may well be okay until you get to a lower elevation. Sorry I didn't think to pull a plug to see what it looked like.

Cheers,
Steve

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#577266 - 05/17/09 10:21 PM Re: Effect of elevation on carb tuning [Re: HealeyPassion]
Lin Offline

Gold Member
Jedi Warrior

Registered: 04/13/02
Posts: 572
Loc: Harrisonburg, VA
Well fellows, Thanks for the feedback and advice. I decided to not change anything this morning. We went over Monarch pass (11,300 feet) without much of a problem. The car clearly didn't like it. I lost power but no real problems and no hiccups. So I will plan to leave the carbs alone for now.

Lin
_________________________
1960 BT7 "The Bloody Beast"
1959 AN5 Bugeye

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#577343 - 05/18/09 09:35 AM Re: Effect of elevation on carb tuning [Re: Lin]
bt7tricarb Offline

Gold Member
Senior Member

Registered: 01/20/06
Posts: 69
Loc: Maryland, USA
Hey Lin. Great to hear your trip is going well...

Several years ago I drove across country in a Mustang convertible (a modern one - 1986 - w/EFI) I owned at the time. I lost power at higher elevations as well, but also remember the fuel being different. I know it was lower octane. Maybe that's changed over the years, but just thought I'd mention it as a possibility...

I imagine you're over the mountains now. Best of luck. I have my car back now. I leave in a little less than two weeks for Georgia.

- Devin

Edited to remove route question... just saw your other post about the return route.


Edited by bt7tricarb (05/18/09 10:10 AM)
_________________________
Devin Williams
1962 BT7 Tri-Carb

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#577427 - 05/18/09 04:50 PM Re: Effect of elevation on carb tuning [Re: bt7tricarb]
Michael Oritt Offline
Luke Skywalker

Registered: 06/28/01
Posts: 1500
Loc: Solomons, MD, USA
I seem to have heard that with sea level settings you lose approximately 5% power for each 1000 foot increase of elevation. I did not change mixture or timing when I ran out to Tahoe in 2002 and never noticed a real loss of power except when going up the very steep Pike's Peak road (14K+ elevation at the summit). I don't remember that overheating was an issue on that climb--we weren't going very fast--but the needle did almost peg on the long high-speed pull up Monarch pass
_________________________
Best--Michael Oritt, 1955 AH 100 Le Mans, 1960 AH 3000, 1958 Elva Courier

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#577849 - 05/20/09 08:45 AM Re: Effect of elevation on carb tuning [Re: Michael Oritt]
Lin Offline

Gold Member
Jedi Warrior

Registered: 04/13/02
Posts: 572
Loc: Harrisonburg, VA
Thanks for the suggestions and comments. I decided to simply go a quarter turn leaner while in the mountains. It did help with running but particularly with idle in the small towns on route 50. I will just readjust when I drop out of the elevation.

Lin
_________________________
1960 BT7 "The Bloody Beast"
1959 AN5 Bugeye

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