I agree with Lawrie, however if this is the prob and he is going to
Daytona I would live with the rough idle while in the mountains. soon
enough he will be back at sea level and they should be OK or adjusted
again. The eastern slope of the Rockies is one long shallow slope to
Texas (remember everything rolls down hill) and he probably better off to
just leave it be. As I recall there was a discussion a while back about
the oxygen content of gasoline at higher altitudes as well. Unless it is
something else.
Larry Macy
78 Midget
>On Wed, 16 Jul 1997 07:48:21 -0400 "John A. Wise" <wise@db.erau.edu>
>writes:
>>Several weeks ago, my son (Mark Wise) asked the list about for some
>>advice
>>about his forthcoming trip from San Jose, CA to Daytona Beach, FL in
>>his
>>MGB.
>>
>>Well he is on his way. He phoned last night from the Grand Canyon. He
>>said
>>he was having agreat trip - loved the drive down the Calif coast road.
>>Over the last day he was experiencingd rough idle and that a local
>>mechanic
>>(in the Grand Caynon area) told him it was the altitude leaning out
>>the
>>mixture. I agreed with that diagnosis, particularly since it is a
>>Calif
>>car.
>
>Sorry, can't help with a Flagstaff area mechanic, but can suggest the one
>he's talked to already should not be allowed to touch the carbs....!
>
>Higher altitude doesn't "lean out the carbs.", it makes them run richer!
>Less air density at altitude, and all that scientific stuff....
>
>So, he probably needs to set the carbs a few flats leaner to improve the
>idle (if he has SUs, that is. If his is a late B with a Zenith-Stromberg,
>it's not so easy to adjust.)
>
>Of course, there are one or two other things that can cause a car's idle
>to go rough (points closing up after a long drive, for just one example),
>so let's hope that it''s something as simple as the thinner air of the
>mountains.
>
>Lawrie
>British Sportscar Center
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