High Flyers - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tucsonjwt · 05-02-2015, 07:00 PM

A question for those who travel to high elevations.

I am at about 3600 feet above sea level and am thinking of traveling to nearby Mt. Lemmon at about 9300 feet with my 83 C20 454/granny 4 speed.

I have read a lot about adjusting the carb for the higher elevation, but it seems unnecessary for a short trip.

What will happen if I just leave the carb as is? My concern is that there is no place to pull over on the narrow road to the top and I don't want to get stuck with my heap up there. I have this image of the engine stalling and my truck coasting backward down the mountain.

Bigstevex4 · 05-02-2015, 10:17 PM

lived in Colorado its not neccecery may run rich keep rpms up. the only time I seen real problems were sea level cars above 10 thousand ft.

dieseldawg142 · 05-03-2015, 01:21 AM

my '85 crew is FI, but my '68 had a 383 with a 1850 holley, and i towed a ski boat & a tent trailer with it with no problems.
i live in the Rockies...

tucsonjwt · 05-03-2015, 05:23 PM

OK - thanks for the replies. I will sign up for road service and cross my fingers.

greg64 · 05-03-2015, 08:47 PM

My truck is jetted for sea level, but I live at 3600 feet, and pass 5000 on some trips. I have a wide band O2 sensor and I can see it running rich at elevation. I would rejet the carb, but I'm changing the whole intake system this summer, so I haven't bothered.

05-02-2015, 07:00 PM	#1
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,188	High Flyers A question for those who travel to high elevations. I am at about 3600 feet above sea level and am thinking of traveling to nearby Mt. Lemmon at about 9300 feet with my 83 C20 454/granny 4 speed. I have read a lot about adjusting the carb for the higher elevation, but it seems unnecessary for a short trip. What will happen if I just leave the carb as is? My concern is that there is no place to pull over on the narrow road to the top and I don't want to get stuck with my heap up there. I have this image of the engine stalling and my truck coasting backward down the mountain.

05-02-2015, 10:17 PM	#2
Bigstevex4 Registered User Join Date: Oct 2014 Location: Spearfish South Dakota Posts: 407	Re: High Flyers lived in Colorado its not neccecery may run rich keep rpms up. the only time I seen real problems were sea level cars above 10 thousand ft. __________________ 83 c10 long Box Daily Driver 90 Jimmy parked 98 Road King/ 06 Road Glide In memorium 63 impala SS/ 65 Chevy Panel 65 GMC Short Box/ 68 Camero

05-03-2015, 01:21 AM	#3
dieseldawg142 Registered User Join Date: Jul 2011 Location: back 40, bc Posts: 3,817	Re: High Flyers my '85 crew is FI, but my '68 had a 383 with a 1850 holley, and i towed a ski boat & a tent trailer with it with no problems. i live in the Rockies...

05-03-2015, 05:23 PM	#4
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,188	Re: High Flyers OK - thanks for the replies. I will sign up for road service and cross my fingers.

05-03-2015, 08:47 PM	#5
greg64 Registered User Join Date: Dec 2007 Location: Kimberley, BC, Canada Posts: 799	Re: High Flyers My truck is jetted for sea level, but I live at 3600 feet, and pass 5000 on some trips. I have a wide band O2 sensor and I can see it running rich at elevation. I would rejet the carb, but I'm changing the whole intake system this summer, so I haven't bothered. __________________ Greg 64 GMC Suburban - 283, NV3500, 14 bolt 77 C10 swb - 292, SM465, 12 bolt



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