Altitude Adjustments

[DCook]

I live at 7000 ft. and a lot of the nice places I can take my M are up from here. I can easily be in the 12000 ft. range in an hour or so. My carb needs some attention, but after I put a few more miles on it to be sure all systems are functional, I'd like to know what options I have for fuel mixture. Then I'll pay some detailed attention to my carb. I now have ethanol-free fuel available locally, but I do not know what the octane is.
Would any of you have charts showing carb piece part to altitude options? My truck is a 51, with standard bore cylinders, cam, head etc.
Thanks
Dana

[PFC1952M37]

First time out with a new purchase and I'm at 14,000 feet, having started at 850 feet..


My only adjustment based on my experience driving single barrel, flat head Mopars was that, as I got higher, I had to lean up the fuel/air mixture.
http://www.allpar.com/fix/fuel/carter-BB.html

[DCook]

You'r correct - Leaner is what I need. Thanks for the Carter info! I have done a number of carbs, and have a stash of jets and small parts. I hope to come up with something that shows jetting to altitude and whatever else is known. I may just have to make my own, and go from there. My CJ3B Navy jeep is a metering rod carb, and I have the highest altitude combination of metering rod / jet available. It is a little harder to fabricate a solution with metering rods.
It is good to know yours was functional @ 14000 ft. you said you leaned it out? How did you make that adjustment?

[PFC1952M37]

Sorry for slow reply. Still breaking in my new replacement shoulder.

No metering rod here. The idle mix is controlled by a needle valve. You just open the air bleed needle for idle fuel mix.

Closing the needle shuts off the air, not the gas.

Some folks think they are shutting down the gas and close the air opening.

The needle will be opened to the maximum setting. Be careful that the tension spring is still holding the air bleed needle so you don't lose it.

Hope this helps.

[Kaegi]

the manuals probably show where to set the timing also for best performance that high up. I don't think I have ever been over about 6 or 7K feet up here in WA but have read posts from guys down in CO that the design works great at any altitude.

[DCook]

Thanks guys,
It is running very nicely at 7000'. I have it set at about 8 deg adv right now. I hope to get it up to 13000' in one of the next few weekends. I'll pass on my success (or lack of it) when I return. I just added a few pictures of it to my gallery pictures from last weekend's car show.
Dana Cook