[Spridgets] Rejetting carbs for high altitude

Paul Asgeirsson PAsgeirsson at worldnet.att.net
Mon Mar 30 14:08:40 MST 2009


When I lived in Colorado Springs, my 1098 van simply ran as at sea level as
far as major carb jet adjustment was concerned.  It did need a minor
adjustment as far as the idle speed went.  Can't remember what it was I did
with it.

The change in altitude height certainly did take away from the "Peppiness"
of the engine, compared to San Diego, but any adjustment was really tiny as
far as idle and running was concerned.  Check the oil level in the carb on a
frequent basis, though, as that can make a real difference in driveability.

Paul A

----- Original Message ----- 
From: "Robert E. Shlafer" <pilotrob at webtv.net>
To: "JLC" <breton48 at live.com>; "'Spridgets'" <spridgets at autox.team.net>
Sent: Monday, March 30, 2009 10:54 AM
Subject: Re: [Spridgets] Rejetting carbs for high altitude


> "He told me if I cannot get the Lotus to run properly, he'll set it up"
>
> Excellent, Jacques.
>
> BTW, I believe Ron S. mentioned lower octane fuel.
>
> The first thing I would do is drain the fuel tank and go with the lower
octane fuel.
>
> If still "rich".....
>
> I would than advance the timing no more than 3 degrees or so, then re-set
the idle mixture/idle speed and give it a whirl.
>
> If still rich, but no "pinging" on acceleration, I might go another 2
degrees for a total of 5 degrees advanced from sea
> level setting.....re-set idle mix/speed and try again.
>
> (If the car starts hesitating (wants to quit) just off-idle, bring the
ignition back 2 degrees, install the warmer plugs....and try again.
>
> Still too rich? Go to the leaner mains and on and on in logical order.
>
> The lower octane gas and/or advanced timing with eat up excess CO
(richness) throughout the whole range and  this may be all you'll need, If
not, I would then go to (ONE step up) a WARMER (not colder) plug. Remember,
you are correcting for LOWER compression pressure (REDUCED effective CR)
than on to leaner main jets if needed.
>
> In the end you have the friendly shop to assist! Glad you found same.
There hadda be somebody around advising the natives and most certainly those
newer to the neighborhood from the "flatlands"!! :)
>
> Cap'n. Bob      '60 :{)
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