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Old 04-30-2021, 05:06 PM
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twobjshelbys twobjshelbys is offline
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Join Date: Jan 2009
Location: Las Vegas, NV
Cobra Make, Engine: Shelby CSX4005LA, Roush 427IR
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Quote:
Originally Posted by FastTom View Post
Hi All

Newbie here...from the Denver area...nearing a purchase of a Backdraft.

I wonder if any of you Colorado folks, who perhaps live along the front range at an altitude of 5,000'+, and often drive up into the mountains, maybe up to 10,000' or more, have any trouble with your carbureted 427s? Is this a non-event, or perhaps a slight nudge toward choosing EFI and a Coyote engine?

(I realize this forum isn't very active...anybody out there?)

Thoughts appreciated

Tom

If you don't go through wild altitude changes a carb'd engine can be set up to operate fine. No matter what you'll lose 15-20%.

If you go from Denver to sea level it will run fine. If you go from Denver and track it at Riverside you'll need to re-jet. Similarly, driving from Denver up Trail Ridge you'll operate fine. If you could find a 14000' track you'd want to make adjustments. Cars have been doing this since, well, forever. Having good tuning at 5000 is ideal. When I was a kid we lived in Iowa, and my dad would have our Suburban re-jetted for Rocky Mountain Park trips since we spent alot of time in campgrounds above 8000'. We noticed the difference when going from low altitude to high altitude for longer operation especially towing.

If you do go from sea level to the top of trail ridge often, then a good fuel injection system can be used on the classic engines. For added visual appearance several manufacturers make a fuel injected "8-stack" that looks like webers. Pretty cool. My small block 427 had the 8-stack fuel injection. Roush didn't get the programming right because they failed to fill in the altitude compensation table but once I did it was fine. New systems do all this automatically.

Everything I said applies equally to a 65 Mustang as a Cobra...

Cobras with period correct engine are lots easier to sell than ones without.
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