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Unread 04-07-2015, 08:49 AM   #1
neal90
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moving and carb question

I will be moving in the next few weeks from NC (very low elevation) to El Paso TX VERY high elevation. My question is how much retuning will I have to do to the jeeps carb. It is all stock except the carb. I replaced it with a MC 2100, might actually be a 2200. Iím just wandering if everything is going to be all outa whack when I move.

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Unread 04-07-2015, 08:52 AM   #2
mastercraftka
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Whats the actual elevation change? I wouldn't guess it would affect it that much.
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Unread 04-07-2015, 09:00 AM   #3
jeepwhore
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x2. And what jets are in your carb right now?
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Unread 04-07-2015, 09:03 AM   #4
neal90
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Its well over 2000 feet higher. I can tell you i have lived in el paso in the past and if you go running you can tell a big change in how you fell when running. Also not sure what jets are in it right now. It was one of the ebay carb kits. I havent change anything from the day i got it except the 2 little screws in the front to tune it.
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Unread 04-07-2015, 09:05 AM   #5
j33ping
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Unread 04-07-2015, 09:09 AM   #6
neal90
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Sounds like I should be good. The elivation in el paso is 3800 feet. I understand from you posted the jets should be good. Do you think it will need any extra tunning??
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Unread 04-07-2015, 10:51 AM   #7
Matt1981CJ7
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A long-time rule-of-thumb for altitude jetting any carb is to reduce one jet size for every 2000 feet of elevation. This has proved spot on for my Weber and Q-jet carbs.

You should also lean out your idle mixture a tad and bump your initial advance a few degrees.

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Unread 04-07-2015, 11:36 AM   #8
j33ping
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Unread 04-07-2015, 11:51 AM   #9
Matt1981CJ7
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Quote:
Originally Posted by j33ping View Post
Matt, fill me in, why are you suggesting changing the initial advance a couple degrees?
Cylinder pressure is lower at higher elevations due to less atmospheric pressure. Therefore the burn is slower and needs to be lit sooner.

I run 15-16* initial advance on my 360, per the FSM high elevation instructions, without any pinging.

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