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ccstelmo View Drop Down
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    Posted: 18 Aug. 2022 at 3:33pm
The problem is, I'm at 10,000 feet in St. Elmo, Colorado.

 I have every reason to believe the main jet is for 5000 and under.   The carburetor parts supplier I contacted (Mikes) doesn't have a jet suitable for 10,000 feet and recommends one drill size smaller for each 1000 feet above 5000.  

Now, I can do that by filling and drilling but what about the metering rod?  It's tapered,  right?  How does that work?

BTW, we're talking about a stock 4-banger with a Carter W-O carburetor.  I'm ready to turn the key and get this thing started for the first time in 5 years but I KNOW altitude will be a problem.  

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Bruce W View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Bruce W Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug. 2022 at 3:56pm
  The best thing to do about elevation and “thin air” is to learn to live with it. There is nothing you can do about it anyway, outside of advancing the ignition timing a bit. There are no “high altitude “ parts available. I watched my Dad try for years, back when parts were available for the carburetors and engines he was working with, and he didn’t gain enough to make it worthwhile. You can’t run as fast as you could at sea level either, but you learn how to live at 10,000 feet by pacing yourself and doing the best you can because, again, there’s nothing you can do about it. 
  I live at 5,000 feet and all of my stuff is tuned to factory specs except for a bit (about 5 degrees) of extra spark advance. I routinely drive my jeeps to your fine little city and above, as high as 12,000 feet and more, with no problems. Yes, power is less than I would have at home, but I’ve learned to accept it and to live with it. As have many others who come from places considerably lower in elevation to enjoy the Fall Color Tours. Put your engine and carburetor together as Willys-Overland intended them, set your ignition timing to 10* BTDC, run it and don’t worry about it. 
BW 
It is NOT a Jeep Willys! It is a Willys jeep.

Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You!

We Have Miles to Jeep, Before We Sleep.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oldpappy Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug. 2022 at 4:09pm
I started to suggest advancing the timing, but I have never driven a Jeep anywhere near that elevation so was hoping someone who actually knows about that, like Bruce, would chime in.

There is a St. Elmo about fifty miles from here, it is near Chattanooga. 
If you can't get there in a Jeep you don't need to be there!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpoole Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug. 2022 at 4:21pm
Very practical advice from BW.  Sounds like he has directly relevant experience and that you'll be ok with the minimal adjustments and living with it.  I'd go ahead and start driving it as is with that in mind personally but wanted to throw out the following to put a few other ideas on your radar in case you choose a different path.

If you do decide to pursue re-jetting and tuning adjustments for altitude the first change I'd make would be to install a real-time, wideband air fuel ratio gauge.  Something like the following (disclaimer I've never used this particular model and just grabbed the first example from google):


I've successfully tuned carbs for elevation WITHOUT real time air/fuel ratio feedback and it took a long time to get right.  That was typically on multi-carb motorcycles that I could get a variety of jet sizes for and that had a lot of available adjustments.  Even with the many jet/adjustment options it was a time consuming process of monitoring performance, engine temps, ignition tune, etc. and repeating until all was optimized.  It was fun at times but I don't ever intend to do it this way again.  With a real time air/fuel ratio gauge you can see how your fuel mixtures perform under cruising, load, idle and other conditions and know for sure how any adjustments impact the ratio as well as knowing where you may have issues.

On one 4 cylinder (VW) that I drove around in the Rockies (Granby area, 8k elevation) it would really struggle at elevation, flood out, not warm start, etc. until I made adjustments.  I made improvements that helped me live with it and then later found out about the air/fuel ratio gauges and was able to dial it in much better which made a huge difference in driveability.

Once you have the actual air/fuel ratio numbers in front of you there are lots of ways you can tune/adjust the air fuel ratio to get it where you want it but that may not apply if you don't go down this path so I'll stop here.  With clear feedback though it can be a lot of fun to experiment with tuning.

Good luck getting the Jeep going again.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CJ2A60 Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug. 2022 at 6:01pm
Originally posted by Bruce W Bruce W wrote:

I watched my Dad try for years, back when parts were available for the carburetors and engines he was working with, and he didn’t gain enough to make it worthwhile.


It's quite a coincidence you should say that.

My Dad, who had a summer place in Creede just below 9000 feet for twenty years and then moved to Durango and continued to drive the high country for another twenty, in Jeeps and Broncos, came to the exact same conclusion.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelyard Blues Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug. 2022 at 6:05pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TERRY Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug. 2022 at 11:49pm
A run of thumb was 1 deg advance over standard for each 1000'  of elevation. Like Bruce, I have found that just the extra 5 deg works. I would get kick back when starting with more advance.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccstelmo Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug. 2022 at 12:10am
YIKES!   That is sooooooo much not the reply I wanted!  

Are you guys telling me that the United States Army sent all those Willys over to Europe where there are mountains called Alps and told the mechanics to "live with it'?

That's "The Greatest Generation" your maligning.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote cpt logger Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug. 2022 at 1:33am
My experience is the same as Bruce's. These engines really do not get much better with "fine tuning" at 5,000' or 10,000' above sea level.

Some folks will disagree, but that has been my experience with almost all the engines that I use at both elevations. I advance the timing a bit & drive. In my 30+ years at 5,000' with trips to over 12,000' I have watched folks try to get their rigs "just right" & IMO it was a real waste of time. Often when they re-jetted their carburetors, they made things worse. One fellow leaned his engine out so much that he had over heating & vapor lock issues, another burned holes in his pistons. Be careful. 

If you want more power, "there is no substitute for cubes" IE: get a bigger engine. A Buick V-6 works well in these Willys. 

I do understand that this is not what you wanted to hear. You can always ignore the advise you asked for. That has been done many times before.

As far as what the US Army did in WWII, I suspect that getting the job done was more important than "fiddling with the Jeep", a Jeep that probably will get blown up in a few hours, days, or weeks anyway. There is a time for addressing minor issues like high altitude tuning, during a war is not that time.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce W Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug. 2022 at 2:39am
Angry  Deleted!

Edited by Bruce W - 19 Aug. 2022 at 2:48am
It is NOT a Jeep Willys! It is a Willys jeep.

Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You!

We Have Miles to Jeep, Before We Sleep.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug. 2022 at 5:47am
No factory high altitude fixes for the 
L-134 Go Devil.
2 factory fixes for the F-134 Hurricane.
Those 2 fixes were available in 1953.
Certainly not a cure for lowered high 
altitude HP but still is an improvement.

Concerning ignition timing. 
There is a reason the factory specification is set at 5* BTC.
That spec gives a bit of leeway for potential mistakes. 
If you inadvertently set the timing 5* more or less from 5* BTC you can run into problems going both directions either advanced or retarded.
If you advance it will be at the risk of going too far.
When you advance too far ahead the intake valve will not be fully closed. 
This is especially true with worn valves. 
If the intake is not fully closed the ignition flame front can backtrack up into the intake manifold. 
That is called a backfire. 
If you have bad valves then shy away from any additional ignition advance. 
If ignition becomes too far retarded then the flame front will not have time to burn all fuel in the cylinder. 
This leads to less power and more unburned deposits and excess pollution.
Each individual engine dependent upon several factors will have a  sweet spot concerning exact best ignition timing. 
Those factors include valve wear, fuel, and compression ratio.




Edited by oldtime - 19 Aug. 2022 at 6:36am
Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

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Post Options Post Options   Thanks (3) Thanks(3)   Quote Bruce W Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug. 2022 at 11:39pm
Originally posted by ccstelmo ccstelmo wrote:

YIKES!   That is sooooooo much not the reply I wanted!  

Are you guys telling me that the United States Army sent all those Willys over to Europe where there are mountains called Alps and told the mechanics to "live with it'?

That's "The Greatest Generation" your maligning.



 

That’s exactly what I’m telling you. There is nothing in the wartime TM’s addressing high altitude operation or adjustments for that kind of use. Nor is there any in the Service Manual for Universal Jeep Vehicles or in Your Operation and Care Manual. 

No one has more respect for the Greatest Generation than I have. Most of what I learned in my first twenty years or so of life was learned from members of that generation. I was raised by two members of that generation, my school teachers were members of that generation, I apprenticed under a member of that generation and worked with several of them. I also served with members of that generation in the military. Im afraid that if you had been standing face-to-face with me when you accused me of disparaging the Greatest Generation, the next thing you would have done would have been to pick your self up off of the floor. 

  Why do you and others come here, where the most knowledgeable people on the subject of early jeeps are, and ask for advice and then tell us we are wrong? Sure makes it difficult to want to help the next guy. I enjoy helping those who need help, but sometimes after a post like yours, I wonder why I keep trying. 
BW 


Edited by Bruce W - 20 Aug. 2022 at 12:39am
It is NOT a Jeep Willys! It is a Willys jeep.

Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You!

We Have Miles to Jeep, Before We Sleep.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Michaeltru Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug. 2022 at 12:11am
Amen, Bruce W.   Always willing to learn here.  Thanks to all who give their advice
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe Friday Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug. 2022 at 12:51am
My personal experience has been that my Jeep stops running well at 12,200 feet.

I agree with all of Bruce W's comments, but offer an old thread with some ideas.

I am not experienced enough to know if what they did was successful.

If someone had a WILLYS part number for the high altitude metering rod rather than carter number perhaps I could research .


http://jeepdraw.com/images/jeepdraw/ADOBE_ACROBAT_FILES/TM9-1826A_Carburetor%28539S%29.pdf


Edited by Joe Friday - 20 Aug. 2022 at 12:58am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gmcjr Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug. 2022 at 9:26am
I wasn’t going to comment, but you did insult a friend of mine. You asked a question, you received a thorough, knowledgeable answer… BUT, it’s not the “magic bullet, just do this” answer you was looking for. So, instead of trying to learn from the voice of experience, you hurl insults. I know Bruce very well, and if you had the cajones to say that to his face, rest assured, you would be on the ground.

Let me ask you this….
You claim you Jeep hasn’t ran in five years, is your gas tank clean of ALL debris and not a rust collector? Are your fuel lines clean, and leak tight? Correct steel lines and flared fittings? Or are they jerry rigged rubber hose and hose clamps? Do you have good compression on all cylinders? Are the points in good shape and set right? Ignition timing? Are you valves set right? Is your air cleaner clean? Are you using the correct solid core ignition wires with the right park plugs? Is your carburetor clean? Does it have a worn out throttle shaft/body? Is the idle set right? Is the metering rod adjusted? If your answer is NO to any of these, worry about those problems. Did you buy a manual, and study it instead of fantasizing about a BS carburetor fix?
Honestly, “altitude” issues are like ethanol gas issues, 99% of the time it’s operator induced and the operator passes the blame instead addressing the real problems. 

BTW, I live at 700ft MSL, I’ve had my flat fender at St Elmo numerous times (it is a tourist trap, you know) and at elevations higher. I and many others have learned that “high altitude” operation is more of a
“maintenance” issue, than it ever was a “tuning” issue. How many Willys Jeeps go to St Elmo in a year without issue? Many. FWIW, I’ve had my JKU Wrangler with all its engine management technology and my turbocharged diesel pickup to st elmo throughout the years…. Guess what? They all lose a considerable amount of power at that elevation.
In a nutshell, can’t change physics, regardless of the generations. Take it up with Robert Boyle and his law if you don’t like it. But, I’m my honest opinion, your not the type that is going to take sound advice, anyways.



Edited by gmcjr - 20 Aug. 2022 at 10:40am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SE Kansas 46 CJ-2A Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug. 2022 at 10:17am
I live at 850 ft above MSL and had real issues with power on my first day at Thirsty Dirt Ranch. Bruce personally vacuum tuned Ol' Red and I had no problems after that...and he showed me how to do it. Sure, Ol' Red had less power in the mountains than she did in the flatlands, but with the flatland tuning she was real sick. I didn't know Bruce very well at that time and I only see him once a year at FCT but he is good people. He is as knowledgeable as almost anyone on maintaining 2A, 3A, and 3B jeeps as well as the MB/GPW and M-38 series.

Don't be so concerned about what the jeep mechanics in War II did but when Bruce gives you advice it is from his long experience as a hands-on mechanic. He is a straight shooter and won't b.s. you. He shares his knowledge. He is good people...kind of set in his ways, but good people.

You do have a service manual, don't you?

Edited by SE Kansas 46 CJ-2A - 21 Aug. 2022 at 9:49am
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U.S. Coast Guard Chief Petty Officer(ret.)
U.S. Army Vietnam veteran and damned proud of it.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lee MN Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug. 2022 at 6:37pm
I’m pretty sure Bruce’s dad is one of the greatest of the greatest generation 💪👍🏽👍🏽 If you do not care for the 70+ year old performance go buy a new Jeep….

Lee
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gmcjr Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug. 2022 at 9:22pm
Originally posted by Lee MN Lee MN wrote:

I’m pretty sure Bruce’s dad is one of the greatest of the greatest generation 💪👍🏽👍🏽 If you do not care for the 70+ year old performance go buy a new Jeep….

Lee

Or sell it for a down payment on a Can-Am or a RZR....
Gary

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