elevation vs. timing
 

i have a question to ask because i have been rattlin this around in my head for a while now
what i am wondering is if elevation changes affects ignition timing. i know that if i tune my carburetor for home(5400 ft elevation) and go to sea level that it will set way too lean because of the more dense air and vice versa, but what if i changed jets to compensate for the elevation change, would i have to adjust my timing also or just leave it alone.

maybe i shouldnt think so much

chevyforever:crazy:

I have always heard the "advance it 1 degree for every 2000 feet" rule (advancing as you go higher in altitude), but don't have anything to back it up with.

I've done that, and it works well with no pinging

John

WOW, someone with a cummins in a chevy 4x4. Ive seen them before and envy you. I wish i had that kinda time. Hows she run? Is it the 12v? I assume your running a divored t/case

My truck is apart right now for paint, and I miss driving it :(

Yep, I'm running a 12 valve... not one of those new fancy-schmancy computerized "overvalved" engines :D

Not running a divorced 205, it's married to the NV5600... was almost a direct bolt-up, just a little time spent finding the proper seal

John

Care to post some pics. I have been thinking about putting a 4bta in a jeep. I need a cj8 really for the wheel base legnth. But put a 5 speed and such in it. I think it would be a killer outfit. Put some lower compression pistons in there, up the boost, bigger injectors, etc. maybe a wheely bar lol. Not really but when i get done with the 67 its a possibility. jt

No pics yet... when I get it completely "done" I'll post a thread with some pics. Engine is turned up a little bit... injectors, tweaked pump, smaller turbo housing, bumped timing... will smoke the (rather large) tires by just rolling on the throttle in 3rd gear :cool:

If fuel prices keep rising, I might have to look into the 3.9 Cummins swaps a little more... I have a rockcrawling 4x4 Toyota that would like to rattle!

John